Modifying Chainstays

[D_Harris]

I assume that chain-stays generally cannot be altered for tire clearance after the frame is built, but has anyone here ever had the chain-stay of a rim-brake bike re-enforced in order to use an adaptor for disk brakes on a frame not originally built for disk brakes?

I'd be interested in hearing about successes and failures, as well as seeing pics of the work done.

Thanks.

Darren

[lorenbike]

I had a Soma disc-specific frame that wasn't properly reinforced and the dropouts bent from the force of braking. If you look at their website all frames within the past couple of years have a new dropout design. After that experience, I'm not sure I'd want to convert a rim frame to discs.

[NHAero]

Paging Weisan, please come to the front workbench!

And find the recent thread on adding discs to a Legend

[weisan]

Originally Posted by NHAero

Paging Weisan, please come to the front workbench!

ahem, I am kinda busy doing some re-stocking....



darren pal, please PM me for details.

[unterhausen]

This was a pretty common mod on rim brake mtb at one time. It took a while before builders learned to add a brace between the says.

I saw some interest in the last year for some reason. Problem is hub spacing, unless the bike is already 135old.

[spoonrobot]

Originally Posted by D_Harris

I assume that chain-stays generally cannot be altered for tire clearance after the frame is built

Dimples can be added or deepened to increase tire clearance, after a frame is built. Sometimes a little, sometimes a lot. It is with hazard, however tales of success seem to be more common than tales of failure.

There are many methods which can be found online. Making a press seems to be the best way to do this but not something most mechanics are going to be able to make or buy:


This is a much more approachable tool and can be put together with everything from a local hardware store in about an hour:


I've used a variant of the above tool to increase tire clearance at the chainstays on two different bikes, one 4130 and one Tange Prestige and both have been fine for a couple thousand miles. It's important to perform more research but increasing tire clearance at the chainstays is a fairly well known and discussed procedure and should be an option for your project.

[NHAero]

Originally Posted by spoonrobot

Dimples can be added or deepened to increase tire clearance, after a frame is built. Sometimes a little, sometimes a lot. It is with hazard, however tales of success seem to be more common than tales of failure.

There are many methods which can be found online. Making a press seems to be the best way to do this but not something most mechanics are going to be able to make or buy:


This is a much more approachable tool and can be put together with everything from a local hardware store in about an hour:


I've used a variant of the above tool to increase tire clearance at the chainstays on two different bikes, one 4130 and one Tange Prestige and both have been fine for a couple thousand miles. It's important to perform more research but increasing tire clearance at the chainstays is a fairly well known and discussed procedure and should be an option for your project.

Meanwhile, we are waiting with baited breath for Weisan to do this to a carbon fiber frame! Onward

[robt57]

I've wanted to do this to my Lynsk/Helix Pro disc. But loosing the warranty seem foolish. Especially considering pre retirement I built up quite a bike quiver to just pull out a different arrow. Still wanna though.

[pinkshogun]

Keep in mind that crimping chainstays on steel frames will decrease your rear spacing a bit

[donevwil]

Not wanting to do it myself I took my MAX frame to Jeremy Sycip who had a couple custom tools for the job. Didn't even crack the paint. The indents added were minimal, just enough to squeeze a 32 where only a 28 fit prior.

[Mark Davison]

Bill Davidson’s shop crimped the stays on my 82 Schwinn Superior so I could fit 650B x 38 tires. They warned me that it might ruin the frame, but all was well. We did this before the frame was powder coated.

[carpediemracing]

I had my aluminum frame "re-stayed", to shorten the stays 15mm. That was maybe 9-10 years ago, and it's one of my two primary bikes (it's my red one).

The builder put on different chain- and seat- stays. The tubing requires some kind of heat treating. I don't know any more details than that.

[d_douglas]

Originally Posted by weisan

ahem, I am kinda busy doing some re-stocking....



darren pal, please PM me for details.

What a timely thread! Yes, from what Weisan has told me, he has some hands on experience with it! Not sure if braking forces are properly factored, but in theory it can be done.

I was mentioning to Weisan that there is an amazing local bike that is for sale where this has been done (converted to disc mount) by the original builder. I am tempted, but tire clearance is circa-2010, so 700x26mm is the reported maximum.

My point is that an expert builder agreed to modify his own frame for an owner, so some feel comfortable with these mods.

[D_Harris]

My problem is that the frame I'd like to modify for wider tires and disk brakes is a Titanium Airborne Zeppelin.



Darren

[kiwisimon]

Originally Posted by spoonrobot

It is with hazard, however tales of success seem to be more common than tales of failure.

I think bicycle modding is like gambling,you usually only hear about the wins.