# Belt drive 29er with Alfine 11spd hub...help?



## bodydriven (May 21, 2011)

I own a Norco Judan Belt and would like to build a wheel for it with an Alfine 11spd hub, while still running the Gates belt drive. I spoke with Gates via email and they said the Alfine 8 and 11 are not compatible with MTB applications because of clearance issues between the belt and MTB tires. I'm wondering if anyone here has experience with a setup similar to what I'm trying to do. Can it be done? If yes, please post pics, links, info, etc.

Thanks

http://www.norco.com/bikes/mountain/29ers/judan-belt/


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## TimT (Jan 1, 2004)

Read this first its sort of long but explains every thing on why it might not work for you.
http://forums.mtbr.com/showthread.php?t=617192
In a nut shell the front ring might hit your chain stay because the Alfine has such a narrow chain line. If you want to go IGH a Rohloff is a better choice. I know this as I dry fit a belt drive equipped Speed hub with a 46 tooth cog on my bike and it cleared the original stay.Saving money now to finish this project up.

Tim


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## bodydriven (May 21, 2011)

Great thread Tim. Looks like I'm outa luck unless I get a Rohloff. I'm not about to chop up my new frame like yours. Thanks for the info.


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## Moozh (Jan 20, 2010)

Hey 'body..' I replied to your post on the other forum (http://www.bikeforums.net/showthread.php/734343-Advice-on-a-29er-with-internal-hub-Anyone).

Again, I'm thinking your's is a trail bike that depending on the terrain you are looking to ride on might just do well with a smaller tire..say 2.0" or 2.1" at the rear and that might be enough to address the clearance issue with the alfine belt-line and still give you enough grip and cush for trails that are not overly techincal. I dunno.. I ran my bike for quite some time with 2" xc tires and they worked well for me, but it wasnt a bike I went bashing about rocks and hucking drops on, presumably you wouldnt be doing that much on a XC bike anyhow.

It will be unfortunate to think that the only IGH solution is a Rohloff...great piece of kit that it is. Very spendy and with the gates' components you are talking about $1500 and a good bit of weight (which we all with IGH already know about and are okay with..).


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## OldWelder (Jan 19, 2011)

*Alfine compatibility*

First off, I am not convinced that spending well into a thousand more on a Rohloff over an 11speed Alfine is the only option. Which is to say you are limiting yourself because there are clearance problems with stuffing a chainstay between a fat tire and the Gates sprocket.

Let's put our thinking caps on here and think outside the box!

Where is it written that a chainstay has to be placed in that position?

Later, OldWelder


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## OldWelder (Jan 19, 2011)

This is my tenth post. I am only making this so they will actually allow me to post links and images. Sorry for the empty content. Its the rule!


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## OldWelder (Jan 19, 2011)

Cdrive frame (no need for a break in the frame to pass a belt through).









Santa Cruse (this is a suspension but you get the idea)


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## OldWelder (Jan 19, 2011)

Whether you have clearance on the Norco with the new CenterTrack is one of those things that you will simply have to buy a sprocket and try it. I have found they present much more clearance then the old sprocket do. Norco Judan Belt will depend on whether Gates comes up with a 28 tooth Alfine cog so the 118 tooth belt length will work. As it stands the 24 tooth cog in CenterTrack is all they offer. Gates claims they will have more cog and sprocket options before the end of this year.

Chain stay center length is where you are also going to run into trouble. The Norco rear center (RC) is 450mm.

Gates Belt calculator shows with currently available CenterTrack systems:
46t sprocket, 24t cog, 118t belt needs 454.97 center, 446.97 minimum center, 456.97 take-up center (looks like the belts too long)

46t, 24t, 115t combo needs 438.31 center, 430.31 minimum, 440.41 take-up (looks like the belts too short)

Conclusion: Even if you do get clearance for the 46t sprocket your Norco is not compatible with the 24t alfine cog. You need the cog to be a 28t (a better gear for MTB too).

I have built a 29er with and 8speed and 2.1 tires. It was tight but it worked. The new CenterTrack gives a little more clearance, several more millimeters.

I will be starting on a build with an 11speed and the new CenterTrack as soon as time allows. I have the parts on the shelf and will post images here as soon as I get it going. I have done drawing based on the Gates stated clearances and it looks tight, but once I got my hand on the parts, I am realizing there is more clearance. Not sure why this is, but so far there is.

Image is of a 26er with an alfine 11sp, 46t, 24t, 115t CenterTrack. I built this frame based on Gates specs and I expected 2mm chain stay clearance but got closer to 5mm. I haven't taken it out for test ride because the frame went to the Hopworks in portland to be displayed above their bar for a while. When I get it back I'll do a compleate build and take it out for a spin. 
















Center Track have smooth back to the belt


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## mattotoole (Jan 26, 2009)

OldWelder said:


> First off, I am not convinced that spending well into a thousand more on a Rohloff over an 11speed Alfine is the only option. Which is to say you are limiting yourself because there are clearance problems with stuffing a chainstay between a fat tire and the Gates sprocket.
> 
> Let's put our thinking caps on here and think outside the box!
> 
> ...


Elevated chainstay frames were all the rage in the late 80s to early 90s. The issue back then was chainsuck, and elevated stays prevented that. I think Mantis by Richard Cunningham was the first of this design, but a lot of brands had them. Most common (and easiest to find now) were probably the Nishiki Alien or Haro Extreme. Any of these should work for a belt drive IGH bike..

I thought about buying one, but I don't want to mess with 26" wheels anymore. My next MTB will be a 29er.

I wish 29er builders would do belt/Alfine frames. Clearance is an issue but easily solvable. Elevated stays are ugly but eliminate the chainring clearance problem, as well as having to split the frame for the belt. That extra joint or removable dropouts is more expensive to build. An elevated chainstay frame is no more expensive or complicated than a standard frame.


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## OldWelder (Jan 19, 2011)

Ah Yesss! Mattotoole,

"Elevated stays are ugly..."

But I think less about pretty and more about function, and the result for me is that function becomes beautiful. You hit on all the points I have constantly rattling around in my old head. These are the problems that keep me awake at night with visions of tube benders squishing out odd shaped structure to accommodate simplicity and allows one to implement available technology in a manner that best suites a need like putting a fat 29er knobby down in the mud driven by Gates belt with the option of gearing the next peddle stroke with a simple click of ones thumb.

Its a simple goal and simple solutions are all it takes.

Check out this thread:
http://forums.mtbr.com/showthread.php?t=590280


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## mattotoole (Jan 26, 2009)

OldWelder said:


> Ah Yesss! Mattotoole,
> 
> "Elevated stays are ugly..."
> 
> ...


Lots of history there. I remember seeing elevated stay Yeti and Mantis bikes in '89 or so.

With "normal" frames, most people don't realize how much work it is to develop exactly the right tube shape to fit everything into that space -- chainring, crank, tire, and a welded structure that will be strong enough. There's definitely cost to this, as well as the fabrication and welding itself. An elevated stay frame can have simple tube shapes that are relatively slapped together.

Through the 80s, the big push was to make chainstays shorter and shorter, for better climbing. Builders were just figuring out how to deal with that tight space. With 29ers we're faced with the same issue again, and the design leaders are the ones who have figured out how to make short stays. Their bikes get the best reviews, and everyone else tries to copy them.

*If we need to stick with "normal" frames...*

One way to address the crowding problem is with a machined/forged/extruded piece in that area, and the chainstays welded to that, like FS bikes have.

Also, why not an all-in-one frame with a removable, changeable dropout to allow derailer, single speed, IGH, chain or belt drive? Current designs would need work to allow the belt, but I still wonder why I don't see more of this. I understand that bike marketing is about fashion, and people want minimalist, purpose-built designs. But we should have replaceable derailer hangers anyway.

Anyway, I can't believe that bike makers haven't jumped on the 11 speed Alfine, and belt drive. I expected a wave of new bikes this year. The almost-no-maintenance MTB is within reach.

A quick and dirty elevated stay frame solves a lot of problems. Taiwan could be banging out a bunch tomorrow, at very low cost.


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## OldWelder (Jan 19, 2011)

I agree, Mattotoole. One solution, and I think this was mentioned on another thread, is that Shimano needs to simply redesign the shifter cassette for the Alfine so the Gates cog can be moved over/offset. If Gates could offset the cog by even 3mm then that would change everything. A 28 tooth cog would help too since I was told by Gates they were not going to support the 39 tooth crank sprocket with the CenterTrack system. 46 tooth is the only choice for lowering the gears for MTB/Alfine combos. Just one more blow to the implementation of this hub for MTB's. 

It is like Shimano wants to keep the MTB application of these hubs at arms length. I can't see why these shifter cassettes have to be placed in the way and why the cogs can't be moved over to gain those preciousness few mm's. The boat is sailing and Shimano is missing it. 

Another solution is to off set the rear trangle, but that means you also have to offset the hub to center the rim back on the bikes centerline. I don't agree with this sort of behavior in design. It will work but what a nightmare for those who would have to maintain the wheel, and that also makes the frame useful only for that application. 

As far as dropouts, Paragon sliders are your solution. They support interchangeable parts for either derailleur or single speed application, and they are cool looking too.

As far as a "Yoke," any way you look at it, I find only about 12.7mm max between the knobs on a Maxxis 2.1 Igniter 29er tire and the 46 tooth CenterTrack sprocket. Not much space to be stuffing anything strong enough with the clearance needed for shedding that inevitable mud and sometimes pencil size sticks or rocks lodged between those knobs. Besides, a tire can wobble enough, regardless of how true rim is, to rub on a stay that close. One also still needs to have a couple of mm's for sprocket clearance too. It can be done, but what a pain.

As I stated, move the cassette shifter, and cog over and that will allow the sprocket clearance one needs to maintain a decent chain/beltline. Come on Shimano; get on board is all I can think.


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## Baloomannen (Jul 19, 2011)

Hi,

Interesting thread! Im really new to MTB but Ive read some on here.

I have a budget of ~$2000 and as I see it now the ultimate bike for me would be a carbon frame 29er with alfine 11 + belt drive. But that doesnt look like it will happen after reading this thread.

Ive also looked at ready made bikes like

Genesis iO iD 11
Charge duster 11

Any thought around these two? Ive googled allot on them but not much to reade there...

Got some questions to you pro's. 
Im a big guy at 6'2 and 220 lbs. Will the Alfine 11 handle my weight/torque?
Ive never built a bike my self, but Im sort of handy. If I go for chain drive. Is it possible to get a carbon frame 29er, Alfine 11, decent fork, wheels, discs + all others inside my budget?

If so please give me some ideas for a spec.

Thanks for a great forum!


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## OldWelder (Jan 19, 2011)

*My New Developnment!*

Hi Baloomannen,

I am not the guy to give you answers on the Carbon frames. I build steel only. It's in my DNA.



Baloomannen said:


> I have a budget of ~$2000 and as I see it now the ultimate bike for me would be a carbon frame 29er with alfine 11 + belt drive. But that doesnt look like it will happen after reading this thread.


I have been working on the chainline issue regarding the Shimano Alfine/Nexus hubs for a while now. With the new Gates CenterTrack one has a little more wiggle room with alignment and clearance. But, given that, and the fact that there is only an 24T Cog available, which makes the lower gears too high for my liking, leaves the situation kind of difficult to maintain a short chain stay on a 29er.

Last week I got sick of *busrting brain cells* and spent some time on my Milling Machine and this is what I came up with for *my own solution*. This is a CenterTrack 28T Alfine/Nexus Cog with a couple of millimeters of offset. Yes, that is right. I did not stutter. A 28Tooth Cog (mounted on an 8 speed not yet tested).









One of the issues I encountered with the larger Cog was it came too close to the shifter cable.









The shifter cable solution was as simple as tweaking/realigning the shifter cassette. The good news is that the cable is now actually in a straighter alignment with the rotator sheave. 









Here are the results after I mounted an 11 speed into a belt drive frame:









The resulting Chainline is about 50mm which is perfect for a 4 bolt Truvativ Stylo 1.1 crank on a 68mm bottom bracket which is also a 50mm chainline:

















Lets do the math: 57.53/2+21.16=49.925 approx. This is based on an Alfine 8. The 11 speed is very close to the same and it is all well within the belt alignment tolerance when used with the Stylo 1.1, 50mm chainline crank. (I might add, a really nice crank too.)

Here are a couple of rough drawings based on a 118T belt, *my 28T Cog*, and a 46T sprocket to scale:








This is a 29er chainstay (Dedacciai S bend) without any clearance dimples. It is almost usable without even dimpling. 









Conclusion. There is hope for this solution!

I can't answer any of your other question except I have been riding an 11 speed commuter for a while now without issue and I weigh 210 pounds.

Later, OldWelder


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## OldWelder (Jan 19, 2011)

One more thought! :nono:

Carbon Fiber for an MTB????


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## Baloomannen (Jul 19, 2011)

OldWelder:
Impressive! You've got some skills with the mill 

I will have to do some more researching before deciding which way to go with my project.
Keep posting pics though, thats always nice to see!


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## BlingBrandon (Feb 17, 2011)

You have obviously put a lot of thought and work into your cog design. I want to run the Alfine 11spd on a moutain bike with a belt drive, but the people at Gates/Spot have tried to deter me. The reason they say is the alfine is a not a mountain hub and suffers from a narrow chainline of around 42mm, whereas most mountainbikes have a chainline of around 50mm. 

Your machining skills have provided a solution to this problem, and will allow us mountain bikers to avoid the only (expensive) alternative that Rohloff offers.

Now the question, can/are are you willing to make/sell another one of these cogs?


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## OldWelder (Jan 19, 2011)

*Selling My Solution?*



BlingBrandon said:


> You have obviously put a lot of thought and work into your cog design. I want to run the Alfine 11spd on a moutain bike with a belt drive, but the people at Gates/Spot have tried to deter me. The reason they say is the alfine is a not a mountain hub and suffers from a narrow chainline of around 42mm, whereas most mountainbikes have a chainline of around 50mm.


My best guess it that Gates/Spot does not want to make these because it means the Shifter Cassette has to be modified/tweaked to use with cogs larger than a 24 tooth. But it is not that hard to do and depending on the frame has to be done at times anyway. I will be taking some pictures to make a Howto on it soon.



> Your machining skills have provided a solution to this problem, and will allow us mountain bikers to avoid the only (expensive) alternative that Rohloff offers.


As I stated before, its more about the shifter cassette and issue of it getting in the way. If Shimano were to have had a different design to begin with then I believe there would have been several different sizes already produced by Gates. It is just that the 24 tooth is small enough to not cause clearance issues with the shifter, so my best guess is that is as far as it got.

My first cog took a huge amount of time to produce. I have been working on some jigs that will actually allow me to go a different direction and make more of these without much effort.



> Now the question, can/are are you willing to make/sell another one of these cogs?


First off, besides being a machinist, I am a custom bicycle frame builder and I was working on this solution for my own Framebones 29er which I call the "ChainSmoker" (see my personal website). But, if there are enough builders, Amateur or Pro, interested in these then I will consider making more. If you or anyone else is interested you can send me a PM and we can discuss it further.

Give me a little time to respond as I am knee deep in the design stage of a build for the Oregon Manifest Constructors Competition which is going to be a really tough one this year.


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## Stopbreakindown (Jun 27, 2011)

Nice work OW. Looking forward to future insight on this topic.


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## bodydriven (May 21, 2011)

Interesting stuff guys. I'm glad you're all working so hard to solve my original problem.  My solution has been to switch to chain drive. Simple as that. I don't miss the belt much either because I had some trouble with the belt skipping under heavy torque, and when I tightened it enough to prevent the skipping, the result was a noticeable amount of resistance in the system due to high belt tension. I think the belt is great on a commuter or road bike but for me it still needs more development time to work well in MTB applications.


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## bodydriven (May 21, 2011)

BTW, my Alfine 11 has been through some great tests (like a 24 hr race on a very tough technical trail with steep climbs) and it held up well. I've also been on a super hard day ride with lots of extremely steep climbs and it worked great. I run a 32T x 23T gearing. So there's been plenty of torque on it. I'm 175 lbs and seem to generate more torque than my friends for short bursts up the steep stuff. My only small complaint is that it doesn't like shifting under much torque so you have to let up for a split second. Overall I'm quite happy with it.


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## OldWelder (Jan 19, 2011)

Hi bodydriven,

Can you tell us if the belt you were running was the old style or the new CenterTrack? 

I honestly haven't had any time using the new CenterTrack, but I have been told it is much improved over the old style. As soon as I get one running I will be giving it the Monument Peak test. If there are any issues they will show up there. 

Most issues I have seen with belt skip are related to two things, incorrect tension or frame flex. Too much drag means it is over tensioned. I built a 29er with a belt a couple of years ago and never once had a belt skip, but that doesn't mean much. It may simply mean I just never taxed it in the same way as you or others who experienced that. I also used Dedacciai chain and seat stays which I have found to be very stiffest. I think with the old style belts, it is just getting the right combination.

Thanks for the Alfine 11 report. How are dealing with difference in chainline while using a chain drive?


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## bodydriven (May 21, 2011)

OldWelder, I am running the old style belt. I also have thought that frame flex could be a cause of belt slip. Not sure what I could do about that if it is.

To run the chain I installed the rear cog (which is slightly dished) flipped around to give me a 46mm chainline at the rear instead of 42mm which is what you get normally. The shift cable was very near the chain so with a little tweak (bend) outward it is fine. Then I moved one spacer from the drive side to the non-drive side on my bottom bracket, so now I'm within 2mm of a straight chainline. The good thing about chains is they don't care as much as belts about perfectly straight chainlines.


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## fabrice (Mar 27, 2006)

Hi,
I'm Fabrice from Belgium.
I hope it doesn't offense if I revive this "old" thread...

I am too in the process of building what will be a Alfine 11sp - belt driven MTB.
But with 2 majors diifferences : tyres will be "fat" slicks, for city use (2.0 and no knobs) so I think no need to care about clearance issues, and it's a 26", so the 24T cog should be just appropriate (with a 46T front).
So what's the problem ?
Of course, belt line...
The CenterTrack belt line is very narrow. I don't know how I could use an MTB crank and get a 43,65mm distance from frame centerline to the mounting surface of the front cog ??
My frame has chainstays that are too beefy : it's not possible to fit a road crankset, the Q-factor is too small.
To add to the difficulty, I use a Trickstuff BB ("Exzentriker"), and this only accepts cranks with integrated 24mm axles (Shimano, some FSA's, RaceFace, ...). So my best bet would be maybe an Alfine Crank (FC-S500) ? IF the following is true :
In the Gates instructions specs, the front sprocket has to be mounted "outside" of the crank spider. Can it also be mounted "inside" to decrease the belt line ?
(I won't get any clearance issue against the chainstay with a 46T)
I feel like a newbie 
It's difficult figuring all this without trying... The problem is the Carbon drive system doesn't cost peanuts 
Now I'm not stuck yet. I'm waiting for the spokes to arrive, so I can build the wheels.
In the meantime, I'd like to set a choice for the crank so that I can order crank & belt + cogs.
Many thanks in advance


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## OldWelder (Jan 19, 2011)

Hello Fabrice from Belgium,

Beltline/chainline is a real problem with the Shimano Alfine hubs when one is trying to use them in the MTB application. Here is and image of a 26er I built using a Sram Apex 5 bolt crank which has a 42mm chainline (standard 10speed chainline), a 115 tooth belt, 24tooth cog, and the 11sp Alfine. Tire is Maxxis Igniter 2.1. This frame has an 68mm eccentric BB. The Sram Apex/Rival GXP uses external bearings. There was no need to dimple the outer chainstay behind the sprocket as there was about 3mm of clearance. The Apex/Rival GXP use their own external bearing and the axle may not fit the Trickstuff. If you can use a crank set with 42mm/10speed chainline that fits your Trickstuff BB then you are set provided you do have outer chainstay clearance for a 42mm chainline using a 46 tooth sprocket. 








More images at Vimana Cycle LLC click on "Gallery" link.









I hope that helps. Check out my next post as it also discusses a 26" belt drive with an Alfine IGH but with a 28 tooth offset cog.

Cheers,


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## OldWelder (Jan 19, 2011)

*Update*

Update:
In my earlier post I demonstrated how my offset 28tooth Alfine/Nexus cog can give one a 49+mm chainline, which works quite well with the 50mm chainline MTB cranks. I have been meaning to get back to this thread with the results of my testing. I still haven't had the time to build a 29er with the offset cog, but I did build a cargo bike with the exact same geometry in the rear triangle as a 29er. The cargo bike uses a 26" rear but the only difference is where the inside dimples in the chainstays are placed and the chainstay bridge. The bike was designed with an Alfine 11, 46 tooth sprocket on a Sram Stylo 1.1, a 118 tooth belt and my 28 tooth offset cog. Below is an image of the bikes rear triangle section with a 29er or 700c rim mounted to it. The crank is designed to mount the sprocket inside of the spider. I used "NO" spacers. A perfect alignment with about 3mm clearance on the chainstay surface after doing a small outside dimple behind the sprocket. There is about 3+ inches of tire clearance where a 29er tire will land between the chainstays. That is plenty of clearance for a fat tire.









Sram/Truvativ Stylo 1.1 crank alignment with no spacers.









These are really nice cranksets!









Mounted here is a schwalbe 26x2.0" but a 2.35" will also work with plenty of clearance 









One more shot of this heavy hauler truck. (Mack Truck)









I took it on a 50 mile field test and my rider rolled in about 15-20 minutes ahead of the pack. He is a real strong rider. It is actually a very fast bike with good high end gears and 1st, 2nd, and 3rd gears that are excellent for any cargo or MTB. The field test was conducted in varying terrain from steep graveled and paved mountain roads to city streets and my rider said he had to use every gear. The new CenterTrack belt does not need to be nearly as tensioned as the old style and never skips a beat. There were no issues with the belt system and the bike has since been sent to a customer in Eugene, Oregon and put to work in a cargo bike business where it sees heavy haul use daily. To date, I have had no calls from the customer with anything but praise for the performance and reliability of the system.

Conclusion: Now that I have available my 28 tooth cogs, it just keeps getting better. I will post more later when I do get a chance to build up a 29er.

You can find more info about my builds at Vimana Cycle LLC


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## fabrice (Mar 27, 2006)

Hi Oldwelder,
thank you very much for your answers, and for the pictures of your great work. You seem to have already plenty of experiences of builds with Center Track belts !
I like your cargofiets 
It's funny that even if you're at the other side of the world (kind of), I've got a hand built steel frame that starts also with a "V" and that comes no that far from you 
It's a Vulture. And he also makes cargo's like yours.
You'll tell me that Oregon is the home of framebuilders ; that's true...

As you'd expect, GXP cranks are not compatible with Shimano Hollowtech2 bearings. The inner diameter is different, at least.
Indeed they look good and are not expensive.
Why did you fit the chain guard on the Stylo crank ? It's smaller in diameter than the belt sprocket, so it has no use... ?

So I'm stuck with Shimano, Race Face, FSA (some), Middleburn (X-type), Aerozine, etc.
But since a typical MTB chainline isn't compatible with a Alfine 11+belt application (unless I got a special offset rear sprocket), and since a road crank is too narrow for my chainstays, I think one solution, if not the only one, is to use that Alfine FC-S500 crank from Shimano. According to their specs, the chainline is 42.7mm, so it's pretty good to start with. The only downside : the arms length is 170mm ; I am used to 175mm cranks (or 172.5 on my road bikes)
Well, there's also the tandem front crank route (from FSA) that I haven't investigated in depth so far. But I cannot find a verified Q-factor value. There's a nice carbon version, but I think it's designed for road applications, with a low q-factor.

Regards,
Fabrice
not yet fully sorted


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## fabrice (Mar 27, 2006)

Me again...
stupid question maybe : is the center track sprockets profile directional, or can they be turned the other way ? (i mean with the writings "inside")
(Since there is some offset to bring the center of the sprocket aligned with the left mounting plane, it could be a way to adjust the belt line)


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## Drew Diller (Jan 4, 2010)

fabrice said:


> Me again...
> stupid question maybe : is the center track sprockets profile directional, or can they be turned the other way ? (i mean with the writings "inside")
> (Since there is some offset to bring the center of the sprocket aligned with the left mounting plane, it could be a way to adjust the belt line)


fabrice: you can turn them around to make small chainline adjustments. The belt line is offset from the bolt flange line by a very small amount (less than 2mm). This doc will give specifics for the offsets, and just double the value to find the difference between one direction vs another.


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## fabrice (Mar 27, 2006)

Thanks Drew Diller 
That's just the answer I was after. It's exactly : 1.55 mm offset ("real" center line / "virtual" center line). So the difference between both directions is 3.1mm.
Incidentally, the usual thickness of a crank spider is roughly 3mm, hence there are 4 possible positions, each distant from 3mm : inwards inside, outwards inside, inwards outside, outwards outside.

The Alfine FC-S500 crankset has a chainline of 42.7mm if the chainring is inside, or 49.2mm if outside. Considering that the spider is 3mm thick, that means the chainring is 3.5mm thick - that makes sense, it's designed for "super-narrow" chains. The inner mount surface of the spider should be about 44.5mm and the outer mount surface at 47.5mm.
According to this, and to the offset of 3.1mm between the mount surface and the sprocket center, the possibles belt lines are : 41.4mm, 44.5mm, 47.5mm, 50.6mm.
The second one is close by less than 1mm from the nominal Gates beltline. That corresponds to "outwards & inside" (just the opposite of the drawings in the Gates instructions).

Looking at the drawings, it looks like the rear sprocket can be also turned around. But the normal fitting has an offset outwards, so I don't know if there's enough clearance to switch the offset inwards... In that case, the beltline would drop by 1.15mm. But, aniway, there's no interest for this in my case (a beltline of 42.5mm won't help).

Sorry if all these calculations are boring, but in my defence, they aren't specific to my own case. They should be valid for any MTB frame (135mm spacing rear, BB 68mm).
Though I reckon it's much easier if the frame takes a road crankset, what mine does not.

Cheers,
Fabrice


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## OldWelder (Jan 19, 2011)

fabrice said:


> As you'd expect, GXP cranks are not compatible with Shimano Hollowtech2 bearings. The inner diameter is different, at least.
> Indeed they look good and are not expensive.
> 
> So I'm stuck with Shimano, Race Face, FSA (some), Middleburn (X-type), Aerozine, etc.
> ...


Too bad on the non-compatible GXP. With a GXP 1.1 the sprocket mounts inside the spider not outside. It is designed that way. What that means is that you can then place spacers between the sprocket and spider which moves the sprocket inboard to meet the chainline perfectly. As it is with my 28 tooth cog I didn't have to use spacers.



> Why did you fit the chain guard on the Stylo crank ? It's smaller in diameter than the belt sprocket, so it has no use... ?


The guard has aesthetic value and also allowed me to not have to go hunt down shorter sprocket mounting hardware. But one can leave it off with shorter hardware. I like the way it looks.

My wife rides a 26er with an Alfine 11 with a 46x24 combo and it hasn't enough lower gears to be that useful for a MTB. It very much lacks that granny gear needed for the kind of terrain we live in, Oregon Cascade Mountains. But she can out run my 29er on flat ground.  It has way more top gears than needed. I used a 115T belt with an ecc bottom bracket. Last week Gates told me the new 42T sprockets will be here by the end of this month, October, which means they may have them by end of winter.  The take-up length between the 46x24x115t belt and a 42x24x113t belt is only +.55mil so the ecc will easily take-up on the latter combo.

Later,

OldWelder


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## fabrice (Mar 27, 2006)

Thanks for replying 

With the Alfine crank too, the sprockets can be mounted inwards. And indeed, spacers can be added too, to reach the perfect beltline. I'll order that crank tomorrow. I've just received my spokes so the wheels will be soon ready and I'll go forward with that project 

You are perfectly right with the gearings, but although the frame I'll use is a genuime MTB one, I won't use it for an MTB application. It will be some kind of "Bad Boy" (à la Cannondale), with 2.0 bald tyres on 26" rims. I'll even use a 22T rear sprocket. I think the gearing will be just right for that use.
Maybe some day I'll fit "moderate" MTB tyres, like Twisters Supersonic that are lying in my garage, for light offroad use ; but real MTB riding with that bike, no way.

Regards,
Fabrice


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## OldWelder (Jan 19, 2011)

Fabrice,

Post images when you're finished.

Enjoy!


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## mattotoole (Jan 26, 2009)

I hope no one minds my bumping this thread, but I hope it keeps going.

OW -- great work! Makes me wish I could have you build me one.


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## fabrice (Mar 27, 2006)

OldWelder said:


> Fabrice,
> 
> Post images when you're finished.


Will do 
But it looks like I'm not yet finished !! 
Well, I've build the wheels, bought the Alfine crank and put it on the bike. Now basically, the only missing bits are the 3 Gates Centertrack items.

First, good news, the crank arms are close, but not hitting the chainstays. That's a good start.
But then, I don't know how Shimano gets a 42,7mm chainline (chainring at inner position) ! My measurements is about 44,5mm. Well, 2mm difference, it could be worse... Using spacers is not the end of the world... Well, if I could ! Because there are bad news : I'm afraid there won't be enough clearance to fit a Centertrack front sprocket, even a 46T, at the inner chainring position. That's the only solution to come close to the nominal 43.65mm beltline : the inner chainring mounting surface is measured at 46.4mm, so with the offset facing outwards (in that case the centerline is aligned with the mounting surface) and with 2.75mm spacers, we are theorically at 43.65mm.
That means I need a lateral clearance of 2.75mm (spacers) + 5.5mm (half the pulley width) = 8.25mm. That's not the case 

In fact my crank is nearly like an MTB crank ; a chainring at the outer position has a 51,5mm chainline.(that's again 2mm more than in Shimano specs)

I need an alternative solution to increase the beltline at the rear cog, I mean like you did with your offset 28T cog.
Apart from machining a whole new cog, what is lightyears beyond my skills, is there an easier way to achieve this ?
I would stick to a 22T cog, it's the best combination with my chainstays length and the smaller front pulley (46T). Unless Gates released a 114T belt, then a 24T cog would be fine too.



OldWelder said:


> Enjoy!


Indeed ! 

Cheers,
Fabrice


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## irrah (Dec 18, 2008)

fabrice said:


> the only missing bits are the 3 Gates Centertrack items.
> 
> Cheers,
> Fabrice


Hei,

Is these Centertrack parts already available ?
I should get lower ratios because I changed the hub, Alfine8 to Alfine11. And I thought it would be a good opportunity at the same time to change the belt and pulleys to newer Centertrack model.

Harri


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## fabrice (Mar 27, 2006)

No, not yet. I've been quoted "early next year".


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## OldWelder (Jan 19, 2011)

fabrice said:


> But it looks like I'm not yet finished !!
> Well, I've build the wheels, bought the Alfine crank and put it on the bike. Now basically, the only missing bits are the 3 Gates Centertrack items.
> 
> First, good news, the crank arms are close, but not hitting the chainstays. That's a good start.
> ...


Are you saying your issue is frame clearance not sprocket clearance? What I mean by that is you need to achieve that 43.65mm center and simply put if your chainstay is in the way then you're out of luck while using a stock Gates cog and sprocket. End of story.

I don't recall, is the frame you are working with a steel frame? If it is then you may be able to dimple the chainstay and achive your clearance. If it is aluminum then obviously all bets are off.

Maybe the alternative is to have a cog made for your project. That may be far cheaper than buying parts and guessing at what will work. Your other alternative is simply have a frame built that is designed for the system. 


fabrice said:


> I need an alternative solution to increase the beltline at the rear cog, I mean like you did with your offset 28T cog.
> Apart from machining a whole new cog, what is lightyears beyond my skills, is there an easier way to achieve this ?
> I would stick to a 22T cog, it's the best combination with my chainstays length and the smaller front pulley (46T). Unless Gates released a 114T belt, then a 24T cog would be fine too.


Regarding available parts. My conversation with Gates last, Friday 11-18-11, the 22T CenterTrack is available right now. The new 42T sprocket and the new 30T nine-spline cog I was told will be here next month. Your hope for a 114T belt is probably not going to happen.

The alternative for me as a designer is to alter the cog design and not shim the sprocket. I am fortunate in the fact that I can do that right here in shop. Changing a cog design to fit my needs is a lot easier for me than buy and throwing parts at a project in hope something will jive. I alway try to stick with building a frame that allows for the use of stock parts. But sometimes to achieve what you want is not possible without alterations. I am fortunate in there is also that core of individuals who trust and are willing to allow me to build, alter, experiment with bleeding edge design so they can have what they want.

The bottom line is that retrofitting an old frame with technologies it was never designed for while on a budget rarely brings success unless you can cut, machine, and weld your way through it. I have to do that on a new design so taking an existing unintended design and making it happen may simply require having friends with greater skills help you.


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## OldWelder (Jan 19, 2011)

irrah said:


> Hei,
> 
> Is these Centertrack parts already available ?
> I should get lower ratios because I changed the hub, Alfine8 to Alfine11. And I thought it would be a good opportunity at the same time to change the belt and pulleys to newer Centertrack model.
> ...


Irrah,

So, if your question is, "I should get lower ratios because I changed the hub, Alfine8 to Alfine11...," the answer is: the Alfine 8 has the same #1 gear as the Alfine 11. Refer back to Post #25 in this thread. The Alfine 11 on that bike is driven by a 24T cog, 46T sprocket, and a 115T belt. If you are a strong rider this works pretty good but lacks that real deep granny gear needed for steep off road trails or steep roads. All the Alfine 11 is doing over the Alfine 8 is giving this bike three more top-end gears that make it very fast on the road for a 26er.

If you need a lower gears, I had a conversation with the Gates folks just last Friday when I placed an order for my latest build, and they informed me the new 42T sprocket is due in next month. My experience is that if they say next month, December, it probably means more like early next year. 

If you have the "take-up" adjustment space to use a 42T then the Alfine 11 will give you a better lower #1 gear and your higher gears will still give you a good experience.

I hope this helps.

22T x 46T Ratio = 1.9090

22T x 42T x 113T Chainstay center take-up = 444.21
22T x 42T x 115T Chainstay center take-up = 455.24
22T x 42T x 118T Chainstay center take-up = 471.91


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## fabrice (Mar 27, 2006)

OldWelder said:


> Are you saying your issue is frame clearance not sprocket clearance? What I mean by that is you need to achieve that 43.65mm center and simply put if your chainstay is in the way then you're out of luck while using a stock Gates cog and sprocket. End of story.
> 
> I don't recall, is the frame you are working with a steel frame? If it is then you may be able to dimple the chainstay and achive your clearance. If it is aluminum then obviously all bets are off.


Hi Oldwelder,
before I tell you what's my frame, sit down 
Its a Cannondale Scalpel (2003 model, so 1st gen family, but not very 1st gen).
Yes a full suspension. Theoretically 67mm of travel.
I've done tests with a chain and cogs, with no shock, and the chain tension doesn't vary in the first part of the travel. Only at the end, it tightens. So with a "platform" shock (Fox RP3) at relatively high pressure, I can assure to limit the travel at acceptable values. Remember that's it's NOT intended for MTB use. It has fat road slick tires (Schwalbe Kojak 2.0).
The main triangle is made of cans, err, aluminum, and the beefy chainstays are made of plain carbon (not hollow). They are so thick that I could nearly file a few mm where needed to make some clearance, but that's a bad idea 
Yes, I have a "frame clearance" issue if trying to achieve a 43.65mm beltline with a 46T front cog.



OldWelder said:


> Maybe the alternative is to have a cog made for your project. That may be far cheaper than buying parts and guessing at what will work. Your other alternative is simply have a frame built that is designed for the system.


Exaclty ! 
If I could have a 22T rear cog with 4-5mm offset, building my bike on a increased beltline would be dead easy 



OldWelder said:


> Regarding available parts. My conversation with Gates last, Friday 11-18-11, the 22T CenterTrack is available right now. The new 42T sprocket and the new 30T nine-spline cog I was told will be here next month. Your hope for a 114T belt is probably not going to happen.
> 
> The alternative for me as a designer is to alter the cog design and not shim the sprocket. I am fortunate in the fact that I can do that right here in shop. Changing a cog design to fit my needs is a lot easier for me than buy and throwing parts at a project in hope something will jive. I alway try to stick with building a frame that allows for the use of stock parts. But sometimes to achieve what you want is not possible without alterations. I am fortunate in there is also that core of individuals who trust and are willing to allow me to build, alter, experiment with bleeding edge design so they can have what they want.
> 
> The bottom line is that retrofitting an old frame with technologies it was never designed for while on a budget rarely brings success unless you can cut, machine, and weld your way through it. I have to do that on a new design so taking an existing unintended design and making it happen may simply require having friends with greater skills help you.


Yeah I know, I started a project that's not the simplest on earth... But creating a unique "Bad Boy" is worth the effort ! (yes it's all black)

What's that "new" 42T cog ? It's the 4x104mm BCD I suppose. It's not an addition to the 5x130 BCD range ?
With a 42T, I would have enough clearance (at 43.65 beltline), but then I don't know if there is a suitable belt/cogs combination for my 434mm chainstays, since the 42T cog don't show in their calculator.

However, the ideal solution would still be to alter the 22T cog to space it out, or to build a custom 22T cog with offset. If you see an opportunity for this in your business, I'd be happy to get a quote on this. Send me a PM if that's the case.

Best regards,
Fabrice


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## OldWelder (Jan 19, 2011)

fabrice said:


> Hi Oldwelder,
> 
> With a 42T, I would have enough clearance (at 43.65 beltline), but then I don't know if there is a suitable belt/cogs combination for my 434mm chainstays, since the 42T cog don't show in their calculator.
> 
> Fabrice


Hi Fabrice,

My calculator includes the 42T 4 bolt 104bcd sprocket. The 42T will be 4 bolt only.

24T Cog
24T x 46T x 115T belt = 438.41mm C-C 1.9166 ratio

24T x 46T x 113T belt = 427.36mm C-C 1.9166 ratio

24T x 42T x 115T belt = 449.99mm C-C 1.75 ratio

24T x 42T x 113T belt = 438.96mm C-C 1.75 ratio

22T Cog
22T x 46T x 115T belt = 443.60mm C-C 2.90 ratio

22T x 46T x 113T belt = 432.55mm C-C 2.90 ratio

22T x 42T x 115T belt = 455.25mm C-C 1.9090 ratio

22T x 42T x 113T belt = 444.21mm C-C 1.9090 ratio

If your chainstays are 434mm C to C and you can use your ECC to increase or decrease your C to C by the needed take-up then you may have several options.

As far as suspension travel increasing the tension on the belt toward the end of the travel radius I personally see may be an issue. But! the CenterTrack tension level seems to be less critical, so you may be able to get away with running the belt a little looser than is recommended, but I believe it remains to be seen as to whether it is too much change in tension to not cause issues. Good luck on that one!

You can send me a PM to let me know what you think.


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## fabrice (Mar 27, 2006)

Hi Oldwelder,
you are probably using the Excel calculator. In the online calculator on Gates Website, the 42T sprocket option doesn't show yet. Anyway, thank you for the data 
It looks like I have to stick with the 46/22/113 since the other combinations are not close enough to my chainstays length, 434mm. Indeed the ECC that I use, a Trickstuff Exzentriker, fits into a standard BSA BB, and provides just a very little adjustment. In fact it's even provided with a half link for a chain application. I would say that the whole range of adjustment is about 3mm.
Of course I was concerned about the chain/belt tension issue, related to the suspension travel. Hence my tests... And I won't use the whole travel. With a higher air pressure than nominal for my own weight, I will limit it to 30-40mm max. For a "road" application, that's more than enough. In that case, the belt tension would vary very very little. And, as you say, I can even adjust it a little too slack, so that when I sit on the bike, it increeases by the right amount.

The only solution I see is a custom rear cog, 22T, with some offset to reach a beltline of 50mm. I will PM you about this !
Regards,
Fabrice


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## OldWelder (Jan 19, 2011)

fabrice said:


> The only solution I see is a custom rear cog, 22T, with some offset to reach a beltline of 50mm. I will PM you about this !
> Regards,
> Fabrice


Fabrice

One of the issues with working with smaller cogs (22 & 24 tooth) is there is not enough room between the cog mounting flange and the inside surface of the shifter cassette cable guide. Which is where one needs to work in order to make the offset on these smaller cogs. To offset the cog more than a couple of mm (2) will cause interferes with the rotation of the shifter cable guide. On the 28T I made the offset was placed further out on the cog's mounting flange and that allowed me to gain more offset. You may still need to move the front sprocket inboard a bit to get into that useful alignment range. By tweaking the shifter arm outboard to gain clearance it causes the shifter cable to ride to outside of the grove. You may be able to shave off some of the inside surface of the shifter cable guide to gain a little more clearance allowing you to crowd the cog over even more.

I understand the cog design is protected by US patent Law with Gates Patent Pending. :nono: It is one thing to make for myself for personal experimentation purposes a cog like the 28 tooth which allowed me to tweak the chainline enough to use a 4 bolt crank, but to infringe on Gates, "Patent Pending" is not my intent. No thank you! I will not make and sell any product that will infringe on the legal rights Gate holds over this design. Even if my intent were to provide a product they don't make, it is still their CenterTrack design and I nor anyone else has the right to make and sell this design. This is the way I see it and I don't intend to find out if there are consequences for selling you a tweaked cog design.

I hope this is clear enough to understand that having me supply you with a Cog is not going to happen.

I am an experimenter, a machinist/welder/framebuilder with a fascination for tweaking things. My reason for feeding this thread is to get others to think outside the box and take on the task of reinventing a design that lacks versatility yet possesses the potential to be useful for more than its original intent. It is Gates and Shimano who need to wake up, look at the potential, and make the appropriate changes needed to service the interest of their customers.

When I said, "... require having friends with greater skills help you...." I meant look up a local machine shop or find a friend with welding and machining skills to help you experiment like racers do when they take a product and modify it for racing purposes.

I hope this make everything perfectly clear.


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## fabrice (Mar 27, 2006)

Hi Oldwelder and thanks for your reply.
Yes I understand, you are not allowed to "copy" a patented design...
So I will first equip my bike with chainring/sprocket and a chain. I have a 18T Alfine cog, and will source a 38 or 39T chainring, to see all the things put together, and ride a little bit the the bike, after all...
Then I'll try to "think out of the box"  to figure if I could modify a Gates 22T cog to tweak the beltline outside.
If I see a possible way, I'll buy that cog and try the mod.
Machining a cog from an aluminum billet is too much hassle for the time being. 

Regards,
Fabrice


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## TrailPig (Jun 20, 2010)

OldWelder said:


> I understand the cog design is protected by US patent Law with Gates Patent Pending. :nono: It is one thing to make for myself for personal experimentation purposes a cog like the 28 tooth which allowed me to tweak the chainline enough to use a 4 bolt crank, but to infringe on Gates, "Patent Pending" is not my intent. No thank you! I will not make and sell any product that will infringe on the legal rights Gate holds over this design. Even if my intent were to provide a product they don't make, it is still their CenterTrack design and I nor anyone else has the right to make and sell this design. This is the way I see it and I don't intend to find out if there are consequences for selling you a tweaked cog design.
> 
> I hope this is clear enough to understand that having me supply you with a Cog is not going to happen.
> 
> I hope this make everything perfectly clear.


Was your 28t cog made by modifying an existing Gates cog or did you start from scratch (I may have resources to modify and existing Gates one, but not to make it from scratch).


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## OldWelder (Jan 19, 2011)

TrailPig said:


> Was your 28t cog made by modifying an existing Gates cog or did you start from scratch (I may have resources to modify and existing Gates one, but not to make it from scratch).


My first cog was made from scratch. I am a machinist and own a very well equipped shop with several well tooled pieces of machinery with DRO's. I have Mills, lathes, and an array of modern welding machines, with over 40 years experience under my belt.

Since the time I made that first cog, I have taken several original Gates CT cogs and machined out the centers and welded in three tab (Nexus) centers with varying offsets to use in real world testing. But it is not just a matter of hacking out the cog and slapping in a different center. The process takes several very precisely machined jig fixtures to accomplish.

I have several people who have been testing my cogs, some on a daily basis, for quite some time now. One is a heavy haul cargo bike that according to its owners GPS has logged well over 500 miles without a single glitch. It is running a 46T x 28T combo with a 4 bolt MTB crank pushing an Alfine 11. The setup has endured a considerable level of stress during its time in service, long steep hills, heavy loads, and a lot of on the go use. Its a work bike.

What I am saying is that I am way ahead of you in that I possess all the machinery to modify, and have modified, and am field testing presently.

As long as the original part is sold by Gates to begin with then I see no problem with making a modification to the Gates part and then offering it for resale as a high performance modification. Gates is out nothing because they have already gotten their cut off selling the original part. Doing a modification to one of their cogs is no different than taking a Harley Davidson engine and remachining/modifying it to make more horse power. It is simply reconfiguring an existing part.

Thanks for the offer, but machining is what I do. I am in the OEM bicycle business and have wholesale access to many parts. I haven't started yet, but I may start offering hubs with pre-installed modified cogs and tweaked shifters as an after market kit or as part of a performance enhanced wheel build. You can watch my website for when I start offering this service. Anyone interested in the modification of an original Gates/Shimano parts can send me a PM and I will keep you posted privately as to when it becomes available. A little more testing and I will feel confident enough to go with it.


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## TrailPig (Jun 20, 2010)

Sounds great OW, I’d be pretty keen to get hold of one of your moded 28t cogs when/if they become available. I want to build a belt drive 26” MTB with Alfine 11 out of a steel hard tail frame I have (Avanti KISS 26 single speed frame with eccentric BB and a Fixie Inc frame splitter).


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## OldWelder (Jan 19, 2011)

TrailPig said:


> Sounds great OW, I'd be pretty keen to get hold of one of your moded 28t cogs when/if they become available. I want to build a belt drive 26" MTB with Alfine 11 out of a steel hard tail frame I have (Avanti KISS 26 single speed frame with eccentric BB and a Fixie Inc frame splitter).


The Avanti website states that the Kiss 26" frame has a chainstay center length of 425mm. You may need to confirm that the ECC allows for more take-up beyond 425mm (e.g. a Bushnell ECC has about 12.7mm of adjustment from minimum to max.).

If 425mm is their max then you are out of luck. If 425 is the middle of your adjustment range then you may be good to go.

Different ECC's may vary in min. to max. adjustment though not by much. You will need to determine your own spec. on that.

Take-up adjustment for tension using a 28T X 46T X 115T belt is 429.94mm ratio=1.164.


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## OldWelder (Jan 19, 2011)

OldWelder said:


> The Avanti website states that the Kiss 26" frame has a chainstay center length of 425mm. You may need to confirm that the ECC allows for more take-up beyond 425mm (e.g. a Bushnell ECC has about 12.7mm of adjustment from minimum to max.).
> 
> If 425mm is their max then you are out of luck. If 425 is the middle of your adjustment range then you may be good to go.
> 
> ...


One more thought is that if 425 is your max then you may be able to go with a 113T belt. Take-up adjustment is 418.91mm, but it would put you on the back side of your ECC.


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## fabrice (Mar 27, 2006)

Hi Oldwelder,
I like that new approach : "high performance modification" 
Let me know when you're ready to start modifying genuine CT cogs.

BTW, my bike is ready (I mean, with a chain  ). It's very fun to ride 
I confirm that there is no problem with the rear suspension.
Here's a little picture just to figure out.
39T chainring et 18T cog for now. Seems OK so far for the intended use. The 11th gear is pretty long, but on the other side, I don't feel the need for a shorter 1st gear...
Regards,
Fabrice


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## OldWelder (Jan 19, 2011)

fabrice said:


> Hi Oldwelder,
> I like that new approach : "high performance modification"
> Let me know when you're ready to start modifying genuine CT cogs.
> 
> ...


Wow Fabrice,

Love it!

Will keep you informed on my progress. You are right about the 11th gear being long. A 28T and even the new 30T will probably not take much away from the top end usability, yet add great advantages to an MTB bottom.

Thanks for sharing your new ride.


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## emperaza (Jan 20, 2012)

Awesome Project! Any recommendations for sourcing the gates components? my LBS is useless.


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## OldWelder (Jan 19, 2011)

emperaza said:


> Awesome Project! Any recommendations for sourcing the gates components? my LBS is useless.


For Gates belts, sprockets, and cogs you can contact:

Chris at Vimana Cycle LLC.

He keeps many sizes in stock.


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## pursuiter (May 28, 2008)

Universal has lots of belt drive kit:
Universal Cycles -- Belt Drive Systems


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## OldWelder (Jan 19, 2011)

Here is a thread to a recent Vimana Cycles belt drive build involving an Alfine hub.

http://forums.mtbr.com/weight-weenies/custom-steel-carbon-townie-project-776150.html


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