# Fat bike chainstays



## J_K (Jan 18, 2010)

I have fat bike frame in plans.
I would like to fit Bud-Lou tires. Not sure if I ever need Lou, but I would like to have that option open.
Fitting Lou will be little bit problematic. It would need heavy dimpling if using Deda 29er chainstays and I'm not big fan of heavily dimpled stays. Another option is using 3/4" round 4130 and bend them, but there's need for big dimples with them too. I have not done any actual fitment, only drawings using Surly tire geometries. According my drawings with deda stays BFL is quite easy fit with very little dimples.

Anyone have done fat bike frame with Lou as a rear tire? What chainstays you did use?


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## G-reg (Jan 12, 2004)

What are you doing for drivetrain? That will be your limiting factor before chainstay clearance.


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## J_K (Jan 18, 2010)

170mm rear, 1x10 drivetrain with either Raceface next sl with direct mount ring or sram x9 with wolftooth components direct mount ring. Should clear lou according to my drawings, but it will be tight.


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## Walt (Jan 23, 2004)

Make your chainstays a little longer.

-Walt


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## J_K (Jan 18, 2010)

How much is good clearance for the widest point of tires? I have done my drawings with 8mm clearance, for 29er I shoot for 5mm clearance, but for the fat tires I would like to have more clearance.



Walt said:


> Make your chainstays a little longer.
> 
> -Walt


That's on option.
I wish the Deda 29er chainstay are little longer, they limit chainstay length little bit.


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## Walt (Jan 23, 2004)

What dropouts are you using? If you use low mounts/Polys/sliders/rockers/etc (ie something with long tabs) you can easily do 500+mm chainstays. Shouldn't be an issue unless you don't like tabbed/plate dropouts for some reason. 

I usually shoot for a minimum of 5mm at each side for the largest tire I'll conceivably use. For XC bikes that's usually a total clearance of about 70mm at the widest point of the knobs.

-Walt


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## J_K (Jan 18, 2010)

The plan is to use Paragons DR2010 dropouts, but lately I have been thinking about using flat sliding dropouts. Sliders would be nice when using smaller tires than Lou.


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## unterhausen (Sep 28, 2008)

go for the Paragon DR2026, DR2034 or DR2030.


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## J_K (Jan 18, 2010)

unterhausen said:


> go for the Paragon DR2026, DR2034 or DR2030.


I want to place brake caliper higher to avoid the snow build up on the calliper, so those are not an option for me. Although it's possible to leave disc mount unused and mount the caliper on the seatstay.


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## BenCooper (Feb 25, 2013)

Last fat bike I built, I used 2Souls sliding dropouts - they have the disc mount above the axle, on the sliding section. Plus, because of the design, you can terminate the CS at an angle to the dropout which was handy on the RH chainstay. 

That was a Rohloff build, though, with offset 135mm rear end.


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## Meriwether (Jul 26, 2007)

I just finished a fatty that I wanted to use Deda big bend CS's but there wasn't enough length *above* the bend to get the bend in the right spot for the widest point of the tire with even 450mm stays. I was hoping to try the new Nova stays since I heard they have more length above the bend but they weren't in stock. So I found a pair of single bend stays I got awhile ago from bikelugs.com (already has a dimple on the outside for the chainring clearance) that worked really well and I didn't have to dimple them. Not sure if any are still around though or where they originally came from. 
The rider wanted a 2x setup so I just went with a Nate on a RD so it's not that hard to get clearance for that setup. The front however will have the Lou. The Lou/Bud's are WAY bigger than BFL's. The BFL's are barely bigger than a Nate on a RD as far as width.

I did some drawings made these notes to myself: (these should be double-checked by someone else so don't take my word on it. These are with 170 hub and 100mm BB shell):
- a Lou/Bud on a Clown Shoe will NOT fit with the SRAM X9 direct drive and a 26t ring, or with a Surly OD 2x crank. Chain hits tire.

- A Lou/Bud on a Rolling Darryl WILL fit if the chainstays are at least 465mm (Moonlander length). But there is very little wiggle room, it'll probably rub in the lowest gear. This is with an X9 single ring or the 2x Surly OD Moonlander crank. Chainline again will suck in lower gears though.

- Nate on a Clown Shoe will fit with the X9/26t crank on 'shorter' chainstays (450). 
It'd be really tight using a regular (non-Moonlander) Surly OD crankset but may fit with longer chainstays (>465mm). 

- Nate on a Rolling Darryl is pretty easy to fit with whatever you want - 2x Mr. Whirly or OD crankset and shorter length chainstays. 

I made a frame that fit a BFL with 465 chainstays and a 1x but it had a bad chainline when in lower cogs. It had E-stays so chainstays weren't in the way.


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## G-reg (Jan 12, 2004)

*Fatty manifesto*

Don't disregard the Paragon lowriders because of snow build up. Reference my #4 thread. I feel like I started that rumor and it's gone wild. I did notice that the caliper on my lowriders collected more snow than the seatstay mounts of other riders. But it didn't cause any noticeable degradation of performance in honestly epic conditions.

I looked at using the Deddidaccciaciia super bendy chainstaystays and found the bends were in the wrong locations to work with a 100mm shell around a big tire. I ended up using that generation of Nova 29er stays(rumor is sourced from TT?).

What's the chainline on the single ring XX1 styler cranks? My #4 build used a 170rear/ClownShoe-HuskerDU/and 2x front rings. I planned it this way and dropped the smallest 3 cogs on the cassette and replaced the third with a 14t "outer" cog, spacing the now 8speed 10s cassette out a few mm. And I still get a bit of chain rub on the tire in the big(36t)cog and small(27t) ring. That's with 3.8 tires, 450mm chainstays, lots of bb drop and a Middleburn 2x rs7 crank.

I had bigger problems with the seatstays than the chainstays. If you are depending on pre-bent items, it's challenging to get the available seatstays wrapped around big rubber.

Here's how I'd hit your goals of 4.8s on 100mm rims with a full 1x10: 
-Use the Race Face fatty 100mm spindle crank, and mount your single ring on the outside ("big") position.

-Offset your rear axle 5mm to the drive side.

-Be able to add some bend to the seatstays.

-Use the Paragon Lowrider Drops.

-Find a compromise with chainstay length and cutting down the lowriders/bends/chain clearance/heal clearance(that's a big one for winter bikes even with 100mm bbs).

I don't want to come off as negative in any way. But I've lost sleep over this exact kind of thing, and executed in metal what I've thought about while not sleeping. 100% happy to discuss things further/be proved wrong.

:thumbsup:


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## J_K (Jan 18, 2010)

Now that's the info I was looking for! Thank you for both of you! :thumbsup:

It seems that bend on the Deda stays is in the wrong place for a fat tires. Need to look another options or do more planning with the Dedas. Actually I was just looking those single bend Pacenti stays, if they are the ones with 17 degree bend. Whit, can you tell me placement of the bend, so I can do some more drawings?
I don't necessarily need room for a Lou and it looks like it's bad idea as chainline needs to be moved more outboard and maybe even needs wider q-factor moonlander cranks. Maybe it's time to make the decision and admit that Nate on a 80mm rim is enough .

Race Face Next SL with direct mount 26t or 28t ring is my first choice for the cranks, the chainline is 68mm and q-factor is 202mm with 175.1mm inside clearance of arm to arm, although they are not available yet.

Then there's 190 rear hubs to give more headache 



G-reg said:


> Don't disregard the Paragon lowriders because of snow build up. Reference my #4 thread. I feel like I started that rumor and it's gone wild. I did notice that the caliper on my lowriders collected more snow than the seatstay mounts of other riders. But it didn't cause any noticeable degradation of performance in honestly epic conditions.


I saw your post about of snow build up, but I was thinking it before that. Good to know it hasn't caused any noticeable degradation of performance, so I will keep low mounts on the list.



G-reg said:


> What's the chainline on the single ring XX1 styler cranks?


Actually I don't know that. Wolftooth Components says the chainline is 50mm for the 73mm BB cranks.



G-reg said:


> I had bigger problems with the seatstays than the chainstays. If you are depending on pre-bent items, it's challenging to get the available seatstays wrapped around big rubber.


I plan to bend my own seatstays.


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## TrailMaker (Sep 16, 2007)

Hey;

Did I see anywhere that you mentioned what rim width you are going to use?


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## J_K (Jan 18, 2010)

TrailMaker said:


> Hey;
> 
> Did I see anywhere that you mentioned what rim width you are going to use?


No I did mention that.
If I go for a Lou I'm going to use 100mm rim or with a Nate I'm going to use 80/82mm rim.


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## Meriwether (Jul 26, 2007)

J_K said:


> Whit, can you tell me placement of the bend, so I can do some more drawings?
> I don't necessarily need room for a Lou and it looks like it's bad idea as chainline needs to be moved more outboard and maybe even needs wider q-factor moonlander cranks. Maybe it's time to make the decision and admit that Nate on a 80mm rim is enough .


The unknown single bend chainstays i got from BikeLugs have a 16 degree bend (not sure the radius). They're not on the website anymore so I'm assuming they were made by True Temper for a bigger company and they were overstock or something. Sounds like the new Nova's may be the best call when they're back in stock, or bend your own. 
Here's my drawing with those stays in place.


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## J_K (Jan 18, 2010)

Meriwether said:


> The unknown single bend chainstays i got from BikeLugs have a 16 degree bend (not sure the radius). They're not on the website anymore so I'm assuming they were made by True Temper for a bigger company and they were overstock or something. Sounds like the new Nova's may be the best call when they're back in stock, or bend your own.
> Here's my drawing with those stays in place.


Thanks for the info!
I think I know where I can get pair of those if needed.


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## Walt (Jan 23, 2004)

Those are the old chainstays that GF used for the Ferrous. They are great! I have a big pile, wish I'd bought more.

-Walt


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## TrailMaker (Sep 16, 2007)

Hmmmph...

I cant seem to make sense of the Surly tire numbers. They just don't jive for me. I'm dumb I guess. I did my spacing calculations the dummy way. I made a cardboard template of the tire mounted on the rim to get the real world shape and measurements. Surest way I knew to do it. Worked like a charm. Whit and I worked on a thread on here about tire profiles and clearances, but I don't remember Lou on Clowns being around at the time. If I had some, I'd sure do my cardboard and scissors thing for ya, pardner.

One thing to keep in mind regarding side clearances is the need for mud room, and also for the rather notorious amounts of runout these blimpy tires can have sometimes. I tried for 10mm per side, and was happy with 8. Good thing, because the tread blocks on a Nate are just a tad bigger than the HuDus I designed for.


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## Drew Diller (Jan 4, 2010)

TrailMaker said:


> Hmmmph...
> 
> I cant seem to make sense of the Surly tire numbers. They just don't jive for me. I'm dumb I guess. I did my spacing calculations the dummy way. I made a cardboard template of the tire mounted on the rim to get the real world shape and measurements.


That sounds like the opposite of the "dummy way" - the distrustful way, perhaps, but in this case that's a positive..


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## G-reg (Jan 12, 2004)

Also my barely acceptable chain rub is barely acceptable because my HuskerDu is stretched out on the Clownshoe. And the widest point is sidewall. If you've seen a Lou mounted up.... It's by far a whole bunch of big ass knobs are at the widest point and won't play well with a chain getting in the way.


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## J_K (Jan 18, 2010)

TrailMaker said:


> Hmmmph...
> 
> I cant seem to make sense of the Surly tire numbers. They just don't jive for me. I'm dumb I guess. I did my spacing calculations the dummy way. I made a cardboard template of the tire mounted on the rim to get the real world shape and measurements. Surest way I knew to do it. Worked like a charm. Whit and I worked on a thread on here about tire profiles and clearances, but I don't remember Lou on Clowns being around at the time. If I had some, I'd sure do my cardboard and scissors thing for ya, pardner.
> 
> One thing to keep in mind regarding side clearances is the need for mud room, and also for the rather notorious amounts of runout these blimpy tires can have sometimes. I tried for 10mm per side, and was happy with 8. Good thing, because the tread blocks on a Nate are just a tad bigger than the HuDus I designed for.


That sounds like how it should be done, I like that.
I would prefer to have wheels and the tires to get actual measurements, but that's not possible yet.


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## Meriwether (Jul 26, 2007)

I have a Bud on a Darryl in hand, if anyone wants the measurements I can post it on the thread Trailmaker references...

But this "table" from Surly is a great start pretty accurate (I think Walt already posted this awhile ago but it's hard to find so here it is again!):
http://surlybikes.com/blog/post/how_fat_can_we_go


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## BenCooper (Feb 25, 2013)

My fat tyre clearance gauge:









I'm thinking of patenting that...


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## J_K (Jan 18, 2010)

Meriwether said:


> I have a Bud on a Darryl in hand, if anyone wants the measurements I can post it on the thread Trailmaker references...


Please post the measurements on the fat tire profile thread.



Meriwether said:


> But this "table" from Surly is a great start pretty accurate (I think Walt already posted this awhile ago but it's hard to find so here it is again!):
> How Fat can we go? | Blog | Surly Bikes


That's what I have been using to do my drawings and calculations, good to know it's pretty accurate.


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## J_K (Jan 18, 2010)

Little update on this.
I have decided to build 190mm rear spaced frame and bend my own seatstays and the chainstays. There seems to be some reasonably priced 190mm specific cranksets available from the RaceFace now.

I'm going to pick up some straight gauge 5/8" and 3/4" tubing tomorrow. Then only thing missing is the tube bender. I tried to get custom mandrels made, but no one was interested of making them. So I'm looking my options now what bender to use. But at least there's a plan now!


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## J_K (Jan 18, 2010)

The chainstays are for welding and brazing.


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## TrailMaker (Sep 16, 2007)

And...

What bending appartus did we end up with?


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## J_K (Jan 18, 2010)

TrailMaker said:


> And...
> 
> What bending appartus did we end up with?


Something very special but nothing too fancy 
Seriously, I will tell once my skills are good enough to justify the purchase of the bender. It's dumb for me to put money in tooling when I'm building just for me, but without tooling you can't make anything.

Meanwhile here is my high tech dimpling toolset.


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## TrailMaker (Sep 16, 2007)

I understand;

On the other hand, there should be no embarrassment involved in any process you come up with that does the job. In fact, there is a proportional quality to this sort of thing, in the more enlightened mind, where the sillier the process, and beyond that, the better the results, the more cred there is to be gained. Rube Goldberg weren't no fool! 

I already had my bender. However, it is a bit of a swallow every time I have to pony up for a new die set. That would explain why, although I have far greater aspirations, I am not doing any bends in anything other than .75, 1.0, and 1.75! Like you, and at $2-300 per, it's hard for me to justify lots of dies just for a hobby... when the shop lights need to work and the car needs gas!

Besides, it's unlikely you've outdone anyone on the "cleverness scale."


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## J_K (Jan 18, 2010)

No embarrassment at all, I just don't want to show it yet. I think there could be even more use for the bender if I decide to build for others, but I don't see myself doing that anytime soon despite there is some interest showing up. I just don't have the abilities or good experience for that, five frames is not just enough.

So far cost per bend has been around $150, that's 4 stays, so not cheap .


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## G-reg (Jan 12, 2004)

Any chance you gave Anvil money to get those bends? I've been trying to justify this very thing myself. 

What I've been rationalizing:

I've not had a single set of pre-bent stays that have the bends in *just* the right place.

Being able to make nice stays with straight gauge chromo tubing for a few $ a foot vs. 20-40 for every pair of seat/chain stays. 

Or being able to adjust the bend to perfect on those spendy pre-bent stays.

That making/acquiring a bender capable of anything near the Anvil would not be cheap either. 

Still need a band saw/good router/hardwood to go the form and vice method.

Would find excuses to bend tubes for all kinds of stuff.


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## BenCooper (Feb 25, 2013)

You could have a look at the Hammill bender - a bit more affordable than the Anvil, and does a lovely job on everything I've tried.


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## adarn (Aug 11, 2009)

Not to derail this thread anymore, but I've been getting surprisingly good results from my super shitty home made bender. If you've got some free time I'd recommend giving it a shot. It ended up costing me around $3 and some stuff I had sitting in the garage. The Anvil one is crazy nice but if you're not bending a ton of stuff or doing big batches it's probably a lot more tool than you really need.


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## J_K (Jan 18, 2010)

For me most important things on the bender are repeatability and way the tube is encapsulated to get kink and buckle free bends. Yes there are cheaper alternatives and I respect that point of view and I also considered of making the bender out of wood.
End of the story 

Hopefully this helps someone, I spend quite a lot of time thinking my options and that's the result.
Keep in mind that if you're going to dimple the chainstays, you need to account that dimpling increases the bend.


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## Testmule (Jul 27, 2013)

*Fitting 4.8s*

I'm going through the same thing right now and am building a couple of frames with Columbus Life tube sets. I cobbled a bending jig out of oak and used a router to carve out the oval chain stay profiles. The tube is so thin it can only be bent a little at a time and it still buckles.

I have done a couple of handmade carbon fatties and even with around 6-7 mm clearance with a Rolling Daryl and a Lou on the back. I still get some tire scrub grinding up climbs because of the carbon frame flex.

I have done ti mountain frames years ago and hope to build some ti fatties in the new year. My twenty year old ti mountain bike that I have put many miles on has lots of bottom bracket flex so I am anticipating the same for the fatties.

The cf fatty I am using this winter has a 1-10 with a race face crank set and in the top gear I get both chain and tire rub but just barely audible.

Surly lists all the specs for the tires.


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## J_K (Jan 18, 2010)

That looks really tight. So you bend those oval chainstays? Are they Life too, so 0.7mm?

Forgot to mention that I have about 146mm space between the dimples, so plenty of clearance and room for bigger tires than currently on the market


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## Testmule (Jul 27, 2013)

J_K, Yes, they are Life stays, .7mm and it is really thin. I also dimpled them after bending to give around 10 mm on a Lou tire per side. This will be my first steel bike, but I have done lots of aluminum, and ti before - it has just been a long time. I'm hoping the steel is more rigid around the chain stays. I'm planning on a curved bridge also.

i know the cf chain stays look tight but there is at least 1/4" there. The tires are also really lumpy and they never seem to mount and spin perfectly round. Nates don't seem so bad as the 5" tires.

As I mentioned, somewhere on the Surly site they have a technical sheet with the numbers on all their tires and how the profiles change on each of their rims.


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## TrailMaker (Sep 16, 2007)

Hmmm...

Dimpling is so problematic. I've never tried it. I have not needed to yet. Seems like it might be a good place for sand filled tubes to try and mitigate the uneven crushing tendency.


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## J_K (Jan 18, 2010)

I see no problems with dimpling. You just need to have die that allows tube to expand vertically. I got even results when dimpled the chainstays.
Just do all dimpling before you have done any mitering.

One reason for dimpling was to shape the chainstay to give it some look, IMO these small diameter round chainstays look too skinny if not added any shaping.
I think 44bikes Kris does best looking 3/4" chainstay dimpling and shaping.


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## Eric Malcolm (Dec 18, 2011)

Columbus Life is heat treated, it does not co-operate with bending.

J_K, what thickness is the chainstay at the dimpled area? Looks like 12mm?

Eric


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## J_K (Jan 18, 2010)

Thickness at the dimpled area is about 12.5mm, I don't want it to be any thinner to be comfortable.


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## TrailMaker (Sep 16, 2007)

J_K said:


> I see no problems with dimpling. You just need to have die that allows tube to expand vertically. I got even results when dimpled the chainstays.


Yes;

Your dimpling looks uniform and smooth. Many do not achieve such results. My exception is a matter of perception of structure. Dimpling "should" be done for the sake of tire/stay/crank clearance. This dimpling weakens the tube in the axial sense (along its length) to bending in the horizontal plane (side-to-side), which it seems to me is the aspect where it is most vulnerable and effects chassis stiffness the most. It is a compromise at best, as I see it. I see little point in doing it for any reason but clearance.

Some aesthetic touches we do knowing they are a mere flourish, and I'm challenging for the lead in that race, at times. Picking your spots is the key to keeping things on an even keel. I prefer to add flare AND maintain structural integrity as much as possible. That "everyone does it" means nothing to me. And, I'd wager a tapered, ovalized, hardened stay is a far different animal concerning its properties than a piece of squashed straight 4130.

Mere opinion and conjecture here on my part, not any personal value judgement against anyone. YMMV.


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## Eric Malcolm (Dec 18, 2011)

TM, I totally agree with you.

A little history at a point of change in Cycle development, my observations only.

Back in the 1970's, Road bike rear wheel spacing was for 5-speed free-wheels and 42t chain-rings. The rear hub width was 120mm. Along came 6-speed free-wheels - spacing now 126mm. We would widen the rear triangles of 5-speeders out to 126mm. Now, some frames had dimpled chain-stays and others had round-oval-round.

The ROR were much more consistant to pull out 3mm each way. The dimpled drive side was super easy and the non drive side similar to ROR.

That's my experience. I don't see how anything that I observe today would change my observation. 

Eric


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## Testmule (Jul 27, 2013)

Fat bike builds have driven the need for greater clearance in the chain and seat stay areas.

I'm curious if there has been data collected on failures of post-manufactured, heavily modified stay materials, including all steels, aluminum, and titanium?

It is common engineering knowledge that a round tube is the strongest structure to be used on a bicycle, but what are the limits to anything other?

I've habited, and have close friends who are owners of LBS's for more than 25 years and seen lots of frame failure, but the chain stay failures that I found most common have been right at the BB area around welds.


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## TrailMaker (Sep 16, 2007)

Testmule said:


> Fat bike builds have driven the need for greater clearance in the chain and seat stay areas. I'm curious if there has been data collected on failures of post-manufactured, heavily modified stay materials, including all steels, aluminum, and titanium? It is common engineering knowledge that a round tube is the strongest structure to be used on a bicycle, but what are the limits to anything other? I've habited, and have close friends who are owners of LBS's for more than 25 years and seen lots of frame failure, but the chain stay failures that I found most common have been right at the BB area around welds.


Indeed;

I don't claim that there is an increase in failures because of dimpling, and frankly, I wouldn't assume there was. I have no test data to show any decrease in lateral stiffness in dimpled stays. I'm merely speculating based on that _common engineering knowledge._ My point is to question dimpling as a convention. In my experience, using 3.8s on 80s, and ordinary 100mm BBs, it is not necessary. Assuming the dimpling will lead to an increase in something - flex - that people want to avoid, why would you add flex for a purpose not in evidence?

Now... if I was dealing with 4.8s on 100s, I'd be begging for that extra clearance!


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## TLKD (Mar 29, 2010)

*Chainstays*

I know this may not be everybody's pickas far as "design" and engineering goes but when a guy wants to slam the rear wheel right up against the BB and still have chainring clearance, the ultimate clearance solution when building out of steel, alu of Ti would be to use a set of plates like those represented in blue in the below drawings. I'm guessing that 1/4" QT100 Steel plates would be plenty depending on how much of the plate is welded on the tube kind of thing...










Very versatile, fits any tubing, adds a bit of length you may need if you're lacking length out of your chainstays. This straight plate design above would allow a guy to use an S-Bend chainstay and use them "the other way around" for a very clean look IMO.

Definately gives a lot of clearance to both the tire and chainrings versus trying to route the tube around the tire and rings.

For the weight weenies, a guess a guy can throw some ball endmilling at them and not affect the strength so it stays on the safe side.

The cool thing is that it's definately something that a guy can cut out of a piece of plate or flat bar with an angle grinder (and a beer) and sculpt his way towards the final shape. For the lazier guys, they can have them laser/ Water jet cutted, costs right next to nothing and saves a bunch of hassles of trying to find a tube that may fit at first and that you know you're gonna have to bend, roll, swag, ovalize, dimple, cut a notch and weld a cap ot it, press and maybe use some hammer persuasion to fit... 

For those who don't like the idea of transfering the "load" of the chainstays from a tube to a plate to the BB shell, the other option out there would be to order a piece of 1/2" x 1" x .065" rectangular 4130 tube and do pretty much what's discribed above but with this tube instead of a plate. This would give you 12.7mm thick to deal with which is bit better than 15-16-17mm. If they had 3/8" x 1-1/4'' x .065" that would be a killer size but they don't.

Just thought that this is a cool option for fatbike chainstays.
That's just my 2 cents anyways !

Cheers.

Thierry


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## BenCooper (Feb 25, 2013)

I've got a full-sus ti Tomac with plates similar to that. The Castellano-type flat plate stays are also an interesting solution - or there's the machined yoke like Paragon and others make.

WRT dimpling, that point on the chainstay is the most common place I see failures, followed by the dropout/CS joint. So I'm always reluctant to dimple unless absolutely necessary.


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## TrailMaker (Sep 16, 2007)

Hey;

Hood that even slightly, and you'd pick up a TON of lateral stiffness. This is indeed a great way to be miserly with space, and is especially good for people that do not have the tooling to bend tubing in tight radii. I would employ this technique 2nd, right behind building a properly shaped box section out of sheet. This one would be far less labor intensive, and may work nearly as well.

What was the OP talking about again?...


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## J_K (Jan 18, 2010)

I have no idea what you are talking, but keep going on 

If I ever do yoke for the chainstays, then I will something similar as Fast Boy did on his UTA bike.
You need to have support between the yoke plates to get lateral support. His design is quite clever.


Take a look on this video @6:45 and see how much the chainstay is flexing when filed, looks like all the flexing comes from the plate.


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## Testmule (Jul 27, 2013)

T_K, 
That video was an inspiration to us all to appreciate our good health. I'm no stranger to multiple surgeries, but no cancers, and am lucky to have everything intact, and funny enough, after the last surgery was the start of my mountain biking 25 years ago. I think of how lucky I am every time I ride which is at least 3 times a week.

The last carbon fat bike frame I did, which is what I'm riding now, I concentrated on strengthening the BB area which can be seen in the pic. What happened was that the flex was just transmitted further back into the chain stays.

Sheldon Brown mentions in his article that BB flex is not the impediment that one might think, in that the flex generated on the down stroke, is returned on the return stroke - not sure if I have explained as well as Sheldon though.
Frame Materials for the Touring Cyclist


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## TrailMaker (Sep 16, 2007)

Ummmm....

Goofy dude. LOVE the stay/BB interface. LOVE IT! Quite a craftsman it appears. *LOVE* it. Good Karma. Truly crappy fate. Just F'n crappy. Totally wrong crappy. Just..............

What can ya say?


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## Walt (Jan 23, 2004)

Fantastic video. What a wrenching story.

As an aside: unless you are dying of cancer, please, please wear safety goggles when operating big power tools. Also a respirator is a good idea if you have your face 8 inches from a joint while you braze it.

Actually, I think I'd do the goggles thing even if I was dying, but to each their own. 

The UTA looks very much like my own favorite hardtail, Stupidmobile. Fun stuff. 

-Walt


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## alshead (Oct 2, 2007)

adarn said:


> Not to derail this thread anymore, but I've been getting surprisingly good results from my super shitty home made bender. If you've got some free time I'd recommend giving it a shot. It ended up costing me around $3 and some stuff I had sitting in the garage. The Anvil one is crazy nice but if you're not bending a ton of stuff or doing big batches it's probably a lot more tool than you really need.


Adarn- did you write about your home-made bender elsewhere? I'd like to see it.


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