# FS&T: Dimpling chainstays



## Walt (Jan 23, 2004)

This is for Todd, mostly, but also for anyone else who's curious.

The process is pretty simple. First, figure out where the widest point of your intended tires is going to be - in the case of most 29ers, this is going to be between 14" and 14.25" or so, depending on the tire size. Mark these spots on both chainstays so that you'll end up with the dimpling an even distance from the dropouts.

Next (for me) I join the dropout to the chainstay, then pull the whole assembly out of the fixture and use my mill vise (my bench vise has seen better days and has trouble with this operation) and a wood block/dimpling bar to put the dimple into the chainstay. Put the stays back in the fixture, and do the BB miter, and you're good to go.

A few things to note:
-Never dimple the stay so much that you ovalize it (ie, from the opposite side from the dimple, you shouldn't be able to see that anything has been done).
-Harder/thinner materials will be much harder to do this with than thicker/softer ones. In this case, I'm using a .8mm heat treated chainstay (a TT HOX5CS). I would probably not try to do this with, say, a Spirit stay. Practice on some scraps before you do any serious dimpling.
-This will get you ~3mm of extra tire clearance on each side, in most cases. It's not a magic bullet, but it'll let you fit a much bigger tire into any given frame if needed. 
-You can use all kinds of things to make your wood block, but I recommend nice soft pine. In my case, I simply cut a groove (drilled a hole/cut in half) that closely matched the radius of the stay, and the wood simply deforms as needed without marking or damaging anything. Hardwoods might cause problems, as could metals, so I'd stick with pine. 
-The dimpling bar, in my case, is a piece of cheap steel that came as part of a handle for something (I can't remember what, at this point). You can experiment with various dimplers to see what you like and don't like, but I've found this to work well for what I want to do.
-I know the pile of rusty chips on the vise looks terrible. I am a filthy slob. 

The final shot shows a completed 29er frame's chainstays w/dimples. In this case, there's about 70mm of space between the stays at the widest point (ie, clearance for a ~2.5" tire) and the BB to DO distance is 440mm. 

Happy Friday, dudes and dudettes!

-Walt


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## swift (Apr 3, 2007)

Good stuff.
Thanks for the write-up.


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## edge (Oct 17, 2004)

Hey Walt, I was wondering if you think it would be ok to dimple a
ti frame after it's already been built?


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## Walt (Jan 23, 2004)

*Never done it*

I know that dimpling/denting things also bends them to some extent, so you may screw up the axle spacing and/or alignment by doing it. Probably best to talk to the builder/manufacturer and get their take.

-Walt



edge said:


> Hey Walt, I was wondering if you think it would be ok to dimple a
> ti frame after it's already been built?


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## smudge (Jan 12, 2004)

edge said:


> Hey Walt, I was wondering if you think it would be ok to dimple a
> ti frame after it's already been built?


you're going to have a hell of a time doing that but it's possible. You will need an extremely powerful clamp of some sort. It's going to depend largely on the type of ti used on the stays. Some builders use CWSR 3/2.5 tubing, some use annealed and some even use CP. You'll have much better luck with the annealed 3/2.5 or CP than you will with the CWSR. Be aware that if you attempt this on a CWSR tube, you risk cracking the stay.


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## shiggy (Dec 19, 1998)

Nice.

My preference is to make the dimple inline with the tube rather than across it. You do not have to have it is as exact a spot and allows for better clearance for various tire heights.

Also creates more of a ridge along the tube rather than a possible hinge point.


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## edge (Oct 17, 2004)

Walt said:


> I know that dimpling/denting things also bends them to some extent, so you may screw up the axle spacing and/or alignment by doing it. Probably best to talk to the builder/manufacturer and get their take.
> 
> -Walt


Yeah, that's what the builder said. I'd need an entire new triangle to get a dimpled chainstay. Makes me feel better about them now that you've given me a second opinion.

I still think I have options. I love the frame and there is a local builder that is willing to take it on. I was thinking is replacing that area with two ti plates or somthin. Kinda like my old balfa minuteman..


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## 20_bandh (May 19, 2004)

What do you all make of this problem.

The granny ring still scrapes against the chainstay even with an extra 2.5mm spacer between the external BB and shell (73mm).

I've sent the frame to a ti specialist builder for assessment and am hoping that he'll be able to dimple the stays "In situ". Do you think this will be possible or will the stays need to be removed and modified or replaced?


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## CheeseSoda (Jan 8, 2007)

I'd just get in there with file and make some room.

Not actually though.
Seriously, don't do that.
Like really.
That's crazy tight though given the spacers and on a 73... Was that frame made to be a dedi-SS or something? What's that do to your chainline how you have it setup in the pic?


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## Schmitty (Sep 7, 2008)

I would get a ball peen hammer and a fist full of guts, and whack that thing. Keep a wheel in it when you do it. Or lay a pipe, etc across it and beat the hell out of it.


-Schmitty-


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## j-ro (Feb 21, 2009)

20_bandh said:


> What do you all make of this problem.
> 
> The granny ring still scrapes against the chainstay even with an extra 2.5mm spacer between the external BB and shell (73mm).
> 
> I've sent the frame to a ti specialist builder for assessment and am hoping that he'll be able to dimple the stays "In situ". Do you think this will be possible or will the stays need to be removed and modified or replaced?


I wouldn't hesitate to smash it a good one with a hammer, it's so close to the bridge and BB that you won't affect alignment at all, just put the peen end of your biggest hammer on there and hit it with another hammer, don't be shy. Just don't use anything with sharp edges.


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## 20_bandh (May 19, 2004)

CheeseSoda said:


> I'd just get in there with file and make some room.
> 
> Not actually though.
> Seriously, don't do that.
> ...


it was never intended to be used as a SS, and was "designed" to be geared and to accept XT cranks which have a chainline of 50mm. I can squeeze XT cranks on there, but I have to use an extra 2.5mm spacer for clearance the result of which is that the non-driveside arm doesn't sit completely on the axle and that the drivetrain is noisy when in the upper gears. 
I am planning to do an Alp crossing this autumn (i've been wanting to do it for 4 years but have never got round to doing it properly) and need everything to be running perfectly. I bought new mechs and a RF Deus crankset (in the pic) which I can't get to fit at all, even with the extra spacer. I reckon I am going to need to get at least 4mm more clearance out of the stay to get a proper fit. 
I've sent the frame to a ti builder in Italy to have the fault rectified, hopefully it will prove to be a simple procedure. I am however going to be mightily pissed off if I end up needing to get new stays fitted.


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