# MITECH epsilon 650b rohloff Awesomeness



## shwinboy (Jan 13, 2004)

This is my latest stop on my Rohloff on dual suspension bike experimentation and I think I've finally found the one. The URT does not deserve all the hate it gets. Jurgen at mitech has really designed this well because it works!


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## shwinboy (Jan 13, 2004)

*Gates Drive defeated me *

I've been shaking this bike down for the last 2 weeks and really I'm super happy with it. The two new things here for me are the URT suspension and the gates carbon drive. I'll Address each separately.

The Gates drive: Well things started off really well. I just put the bike together and everything worked perfectly. The gates drive was silent for the initial 2 hr ride and I put the bike away. The next day however was different. The belt was now clacking as it went over the sprockets. So i figured the shakedown ride just knocked something out and I just had to tighten and re adjust things. So each successive ride was preceded with a tune to get the belt silent which it would be for the whole ride then the next day somehow hanging in the shed knocked everything out of alignment again. The second week things got worse as now it was impossible to completely eliminate the clacking which could be felt through the pedals. I tried high tension, low tension, shimming the sprockets in all directions to no avail. With out the belt on my cogs were in perfect alignment all my slider bolts were tight . I could tell the problem was the centertrack rail slightly snagging on the teeth but nothing I did could appease the gates gods. Realizing I was spending more time trying fix the bike than riding it I just put a chain drive on. It's quiet now.
Am I done with the gates drive? Not yet there's one more thing I want to try as I paid good money for this stuff and have a frame built for it. I'm gioing to try cutting the square edges off the inside of the centertrack teeth with and exacto blade as I'm pretty sure this is where the problem lies. A slight taper should aid in a quieter engagement of the rear sprocket.








The URT suspension:
This is my third rohloff dual suspension bike. The first two were Haro Sonix with EBBs for chain tension duties. The Haro's basicly had a concentric pivot with some linkages added to try and negate the poor pedaling characteristics of that design. They were ok but pretty bad in two regards. 
They were awful to climb. Concentric pivot bikes want to fold in half when you are climbing steep stuff in low gears. They were horrible in or out of the saddle climbers.
Concentric pivot bike are also terrible when it comes to square edge hits due to the pivot location. The wheel can only travel up and forward when it hits something when really you need it to go up and back. With a heavy weight like a rohloff on the end of the swing arm you really can feel the loss of momentum as the wheel feels like it hangs up on stuff.
It's why I steered clear of bikes Like the Lenz Milkmoney or SVO offerings.

Ultimately the claimed good climbing traits of the Sweetspot URT design are what attracted me to this design . A rohloff Dualie is going to weigh around 14kg so the last thing I wanted was a heavy bike that was also a chore to climb. You can find a lot of hate on the internet about the URT design but in my opinion after riding one with modern geometry and shocks most of it is undeserved or blown up to mythic proportions.
By and large it rides like a high forward pivot bike except there is zero chain tug and it bobs less . The high forward pivot really is a good partner for a rohloff as it's rearward axle path helps that heavy hub get up over stuff. The oxide Battle axe  uses a high forward piviot as well probably for this reason.
The Mitech Epsilon climbs phenomenally well in or out of the saddle. Hands down the best technical climbing bike I've ridden. I love it a lot for this reason. It's still a heavy bike so its not going to be the fastest up but it will tractor up stuff with the best of them.
But the BB moves changing the seat height all the time?! (The internet screams) I don't actually notice it even when I'm trying to. You know what I do notice when riding non urt traditional suspension bikes of all otther designs? Chain tug! All the time. That is far more noticeable than the moving bb on this URT.
Descending: The interwebs will have you believe that the suspension stiffens and doesn't work when you are out of the saddle. This is more a perception thing as you are perceiving through your feet which are attached to the swing arm so it feels a bit different but that swing arm is still moving and compressing the shock. I actually think the weight of the rohloff hub does more to impede DH suspension performance than the URT design. I also come from riding hard tails a lot so this bike works better than a hard tail but not as good as a giant Trance when pointed down. The Geometry on the Epsilon is also more conservative in the head angle department at 69 deg than modern trail bikes but still has heaps of reach. I like how it handles and when I do get it off the ground the bike is really balanced.
Brake jack and braking suspension lock out. Weather you are riding an Orange Five or a Mitech epsilon you will experience these traits. Any high forward single pivot design will do this. You adapt and ride the bike accordingly but on the mitech ; No chain tug.

I think I've covered most things. I will add any new revaluations to this thread. If there is a parting thought it would be not to be afraid of the URT. It's a compromise for sure but it's no where near as bad as the Internet would have you believe. Unfortunately I wish I could say the same for the gates carbon drive. I will give it another go when I have the time.


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## Velobike (Jun 23, 2007)

That's an interesting bike, and going against the trends. Suspension is always a compromise so it's all about optimising the good and minimising the bad of each variant. Looks like they have found the answer for URTs.

The Rohloff belt problem is almost certainly due to some flex in the chainstay area. I have done a number of conversions and the clacking only occurs on bikes with some lateral flex in the chainstay (assuming belt tension is ok). Lateral flex is not necessarily a bad thing - it is what gives some bikes their "feel" characteristics - but it's not good for a belt drive. I found bikes designed for single speed were best for belt drive conversions because they generally had the laterally stiffest chainstays.

It might be worth testing that. I have given up on belt drive for mtb use although I very much like it for road.

I'm looking forward to seeing how your belt modification works.

BTW I don't know if you have carved up stuff like tyres or belts before, but it's very easy to slip and carve yourself or damage the object because a fair bit of force is needed even with a sharp blade. If you dip the blade in diesel it will cut much better and with less pressure, so a slip is less likely. Obviously you'll need to thoroughly degrease the belt ASAP afterwards.


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## shwinboy (Jan 13, 2004)

Yeah there is some flex in the stays that I can detect. The bike was designed to take the gates so I was a bit surprised at how easily flexed the stays were. If I tensioned the belt to the high end recommended for the rohloff it did pull the stay across. At the bottom end of tension I had the best results but still couldn't get it to run cleanly despite all being plumb. Only under tensioning it could I get the clacks to go but then I get belt slip. An $80 snubber would probably fix that but it's not the Gates dream I signed up for. I probably only need to remove a sliver of material from each tooth to make it work but priority is low. The chain drive I installed works so well that I finally got to just concentrate on the ride and not noises from the bike. 
Thanks for the diesel cutting tip.


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## Velobike (Jun 23, 2007)

I don't like snubbers either, but they can be very effective.

I did one conversion on an elevated chainstay bike which was fine until heavy pressure was applied, and then it would clack.

After a bit of experimenting I came to the conclusion (as have others) that setting the snubber at around the 7 o'clock mark about a millimetre clear of the belt will do the job. That means it only contacts the belt when it starts to ride up. You may be able to get off with setting it closer, but the trick is keeping it just clear under normal operation.

Seeing as you do have flex, I reckon leave the belt alone and concentrate on getting the snubber right. I made my own from an old SS tensioner - $80 sounds too much for what is simply a roller and a locating arm.


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## fokof (Apr 24, 2006)

3 of my regular bikes have Belt and I never had problems once the setup is good to go.

One thing I might add to the lateral flex is that it needs to be PERFECTLY aligned.
Chain line perfectly aligned between the Chainring and cog.

I had noise coming from a 1mm offset when I got my first Belt bike.


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## Velobike (Jun 23, 2007)

fokof said:


> One thing I might add to the lateral flex is that it needs to be PERFECTLY aligned...


Good point. You'd hope alignment is not a problem with an expensive frame designed for belt drive, but it's possible to introduce variations with the mounting of the cranks and wheels. Especially if someone got overenthusiastic while facing the BB shell.


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## fokof (Apr 24, 2006)

Or a 2,5mm spacer on the wrong side on the BB assembly.



Rohloff chain line for belt is 54,75mm
https://www.rohloff.de/en/experience/technology-in-detail/specifications/

I don't know much about Shimano products but I see that some XT crank have a 50mm chainline, others 48 ....... there might lie your problem.
https://bike.shimano.com/en-US/product/component/deorext-m8000/FC-M8000-3.html

You can correct the chainline outward but over 2/3mm is maybe too much.
By mounting the chainring opposite side (writings toward the frame) gives you a 2mm play.
You can then add some washers to get to the right chainline.

I use a long ruler to check if everything is aligned.


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## shwinboy (Jan 13, 2004)

My belt line between the belt sprockets when installed is spot on. I use a long steel ruler and even measured and shimmed everything at the bb end to match the 54.7 Rohloff chain line. This is why I could go for rides and it’d be fine. But the next day it wouldn’t. So something is changing between finishing a ride and the next day. At this stage I’m even thinking it could be thermal expansion of the frame. The problem seems that it is way more sensitive to minor misalignment than I was led to believe. It could be the gates or the frame is poorly designed. It could be the splined cog carrier on the Rohloff is the problem as they have just released a new one that uses a lock ring instead of the spring retainer sighting “ micro misalignments” as the reason. This could be my problem. What ever it is I’ve almost exhausted all the free fix options. Not too keen to throw more money at it for a snubber or new cog carrier when now I have a chain on and it’s flawless. Like I said I have a few more ideas I’d like to try when I have a bit more time to tinker.


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## Velobike (Jun 23, 2007)

If it's happening after the bike has been parked, it could be as simple as the dirt on the belt drying or compacting.

My conclusion with belts on a mtb was that in dirty conditions, they really need to be enclosed to keep them dirt free. In which case a chain is just as good. 

Maybe it's as simple that belt development needs a few more iterations for mtbs. I would really like a perfect belt system for my mtbs because I like a silent bike.


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## fokof (Apr 24, 2006)

IME , when the setup is good , it's flawless.

The first one I had was 5 years ago , my main MTB , I never had problem since the setup is perfect. but I must admit that I had to put some time for the chainlink to be perfect with a Hollowgram crank. It has seen lots of dust and mud and never had the need for to protect it.
It's the same belt , never changed it so far.

I have a belt on my Fatbike too , same thing , for three years now. Loads of snow and slush (north east Canada) spot on.

I got a new commuter this year , a Cannondale Badboy ,has a belt too (I'M becoming a fan ) only have a couple of months and it is only commuting but so far , it also is dead silent and perfect. It came with an Alfine , it was VERY silent ...... I changed it for a Rohloff , and I now get the usual Rohloff noises.

I don't think that the CDX belt has a design flaw.It must be something else if your belt setup is OK.
You should ask your bike mfg if they past the rigidity test:
https://www.gatescarbondrive.com/frame-stiffness-test-general-instructions

Maybe it's a mix of different noises (Including the noise of the Rohloff)
Hard to tell ......

Good luck !


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## fokof (Apr 24, 2006)

An idea : is your wheel mounted straight sideways ?

It could be a wheel a little out of dish + sliding dropout not aligned , making the hub a little sideways .... ???


(It's hard to mount a Rohloff hub out of dish !! )


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## shwinboy (Jan 13, 2004)

Velobike said:


> If it's happening after the bike has been parked, it could be as simple as the dirt on the belt drying or compacting.
> 
> My conclusion with belts on a mtb was that in dirty conditions, they really need to be enclosed to keep them dirt free. In which case a chain is just as good.


It's not a dirt problem. I live in dry dusty part of Australia. I get dust which made the belt squeak and fixed that with silicone spray.

I have a belt drive with an Alfine on the commuter and it has never needed any attention from me ever. It's why I thought I'd give it a go on the mtb.


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## shwinboy (Jan 13, 2004)

fokof said:


> An idea : is your wheel mounted straight sideways ?
> 
> It could be a wheel a little out of dish + sliding dropout not aligned , making the hub a little sideways .... ???
> 
> (It's hard to mount a Rohloff hub out of dish !! )


Yeah tried that. It has some impact but I never got better results than just centering the wheel in the frame.


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## shwinboy (Jan 13, 2004)

fokof said:


> I don't think that the CDX belt has a design flaw.It must be something else if your belt setup is OK.
> You should ask your bike mfg if they past the rigidity test:
> https://www.gatescarbondrive.com/frame-stiffness-test-general-instructions
> 
> ...


The Mitech Epsilon is on the Gates frame list. https://ww2.gatescarbondrive.com/Manufacturers-And-Models

It's not Rohloff noises. I know what it sounds like. Initially when I encountered the noise I thought it was the BB or pedal bearings as those were transplanted from my old bike. It's definitely the belt interfacing with the rear sprocket that is making the noise. It's a clacking as the belt tooth settles into the sprocket and exits. It is alignment for sure. All investigation indicates that either the rear sprocket is out too far (possibly caused by belt tension) or the front sprocket isn't out far enough. I can't change the rear sprocket spacing and I've tried shimming the front sprocket to no avail. It's very perplexing as the Aussi rep told me the system could tolerate a 1mm miss alignment. The alignment when belt is off is spot on but unfortunately the ruler method for checking alignment doesn't work when the belt is on as the belt is wider than the teeth. So it's hard to know for certain or quantify how much influence the belt tension has on the alignment. I'm open to suggestions.


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## sam-eye-am (Jun 30, 2004)

How are you measuring tension on the gates? Phone app or an actual gauge?

While not an mtb, I have a coupled commuter/tourer running rohloff and gates. I had similar noise issues as you described after the first 300 miles or so. It was a bit difficult to diagnose as it is similar to the sound my frame will make under moderate to heavy pedal applied tension if one of the couplers isn’t dead right. 

Nothing worked for me long term until I got the gates tension gauge and gave up on using the phone app. Once I set it with the gauge, it has been silent for at least 1k miles, maybe closer to 2k and hasn’t been fiddled with since. 


Sent from my iPhone using Tapatalk


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## shwinboy (Jan 13, 2004)

sam-eye-am said:


> How are you measuring tension on the gates? Phone app or an actual gauge?
> 
> While not an mtb, I have a coupled commuter/tourer running rohloff and gates. I had similar noise issues as you described after the first 300 miles or so. It was a bit difficult to diagnose as it is similar to the sound my frame will make under moderate to heavy pedal applied tension if one of the couplers isn't dead right.
> 
> ...


Yeah I'm using the phone app. The kricket gauge is $75. Not that keen to throw more money at the problem but that would probably be the best target. Is the phone app really that useless?


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## Velobike (Jun 23, 2007)

shwinboy said:


> ...So it's hard to know for certain or quantify how much influence the belt tension has on the alignment...


For this you'll need another person.

Clamp on the back brake, set the rhs pedal at 3 o'clock and one of you stand on it. The other person observes from the rear. They should be able to see if there's any flex, even if it's only 1mm.

The easiest bikes to set up are singlespeeds on a freehub because you can deliberately set it up with negative alignment which disappears under pedal tension, although that's still not ideal.


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## shwinboy (Jan 13, 2004)

Velobike said:


> For this you'll need another person.
> 
> Clamp on the back brake, set the rhs pedal at 3 o'clock and one of you stand on it. The other person observes from the rear. They should be able to see if there's any flex, even if it's only 1mm.
> 
> The easiest bikes to set up are singlespeeds on a freehub because you can deliberately set it up with negative alignment which disappears under pedal tension, although that's still not ideal.


This kind of makes sense as I did have it setup one day where under pedaling tension the sound would disappear but if you were soft pedaling it'd be all clack clack clack. It would seem from everyone's input that frame flex might be a significant factor to the trouble I'm having..


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## sam-eye-am (Jun 30, 2004)

shwinboy said:


> Yeah I'm using the phone app. The kricket gauge is $75. Not that keen to throw more money at the problem but that would probably be the best target. Is the phone app really that useless?


In theory, the phone app should work. But, since vibration is a function of the systems mass and material types, I think there is too much variability in harmonics of the entire drivetrain and frame to be a reliable indicator across many different configurations.

I played with the phone app after using the gauge. I don't think I was able to get better than 1 in 3 belt plucks to agree with being in the desired range after setting tension using the gauge. For me and my ride, that means the phone app is useless. Another week or so and I'll finally get a belt drive fat bike built up so I'll have another data point.

Sent from my iPhone using Tapatalk


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## shwinboy (Jan 13, 2004)

Gates Belt problems MYSTERY SOLVED! I had another crack at making the gates drive work. Turns out the problem was an alignment one. Instead of using a thin steel ruler to check the alignment, like I was previously, I used a thick spirit level that could sit on the tips of the multiple cog teeth. When I checked the alignment like this it clearly showed the rear sprocket was sitting 3mm outboard of the front cog. I Installed some 3mm spacers under the front cog and my Gates belt drive dream is alive again. Huragh! all done inside of 30 minutes.


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## Whiptastic (Mar 14, 2016)

The sweet silence of belt drive! For others reading this trying to diagnosis odd clicking noises in your drive line, be sure to check that the pedals are torqued tight. I had a clicking noise that baffled me for weeks. Turned out to be the copper washers I had used to protect the crank had compressed enough to allow the pedal to work ever so slightly loose.

I’m a IGH and belt drive convert and have serious Rohloff envy. Lol... Some day!


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