# Creating subtle dimples on chainstay for wider tires



## SilentAssassin (Jul 29, 2010)

I bought a used touring bike that I plan to commute on. I want to use these big wide tires but am running into rear tire chainstay clearance issues. Tires are a little bit wide, and though they actually do have 1mm clearance from the chainstay, the side of the tire will rub if the wheel is even slightly out of true. I definitely need a bit more clearance and I know that to get that clearance I need to form dimples on the inside of the chainstays. Not too sure how to do this, and there isn't much documentation on the web. Definitely will take the bike in to a shop though as I do not want to ruin a perfectly good frame. Here is a picture of what I'm talking about. Note the lower right hand picture is the dimples that I'd like to create. Andy thoughts / ideas on how to form these dimples let me know.










Looks like the tire is mounted on backwards...doh


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## cyclust (Sep 8, 2004)

I'd say your chance od success is roughly equal to your chance of ruining your frame. I'd simply use a slightly smaller tire and live with it.


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## SystemShock (Jun 14, 2008)

Another possibility is to do a 650B conversion... run smaller-diameter wheels with fat tires. This will improve chainstay clearance a bit, as the smaller diamater wheel puts the tire a bit further away from the narrowest part of the chainstays.

The diff wouldn't be dramatic, though- maybe 4 or 5mm more total chainstay clearance, or like 2mm on each side of the tire.

You can't do this if you're running cantilever brakes (unless you have some framebuilder guy move the brake bosses for you, which I doubt is cheap), and even with sidepull brakes you'll need a new set of 'long reach' sidepulls (rivbike.com sells these).

And, oh yeah, the wheels would run you some dough too (rivbike also sells some $200-250 650B wheelsets). Might make sense if you've always wanted to upgrade there (smaller-diameter wheels will spin up faster and be lighter, all else being equal), but if you're looking to not spend a significant amt of $$$, then I'd go with Cyclust and say run a slightly smaller tire and live with it. 
.


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## SilentAssassin (Jul 29, 2010)

Nah, don't want to go with smaller wheels. That just makes things more complicated. Dimples is the key. If you look at the lower right picture that frame has dimples specifically for this purposes. It's just a matter of creating two dimples. I'm sure if I just take it to a builder they could do the mod for $30 and make sure alignment stays in tact. It's a steel frame BTW. 

This is what little info I've found on this:

http://www.frameforum.org/forum2/index.php?showtopic=1866

http://www.velocipedesalon.com/forum/f2/framebuilders-q-diy-chainstay-crimp-8185.html


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## JCavilia (Sep 12, 2005)

Those "dimples" you see on some frames weren't formed by some frame builder or bike shop bashing the tubes with a hammer after the frame was built. The tubes were made that way by the tubing manufacturer, or the shaping was done by a builder before the frame was welded or brazed together, Trying to re-shape the tubes on an assembled frame will likely damage them, and will almost certainly distort the alignment of the frame. You're barking up the wrong tree, IMHO.


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## SilverStar (Jan 21, 2008)

A competent builder could probably add the dimples...which could be relatively easy or could require new chainstays altogether. Even the easy way, I'd be damn surprised if it was a $30 process. Sounds like slightly narrower tires might be a more economical (and logical) solution.


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## Mootsie (Feb 4, 2004)

Cut a mm out of each dropout. It will move the tire back to give you the space you desire.


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## Mike Prince (Jan 30, 2004)

SilentAssassin said:


> Nah, don't want to go with smaller wheels. That just makes things more complicated. Dimples is the key. If you look at the lower right picture that frame has dimples specifically for this purposes. It's just a matter of creating two dimples. *I'm sure if I just take it to a builder they could do the mod for $30* and make sure alignment stays in tact. It's a steel frame BTW.
> 
> This is what little info I've found on this:
> 
> ...


Plus what the painter would charge to repaint the modified area as the paint would at least crack in that area. There's really no good way to do this by tweaking the frame IMO. Best case is that the bashing in of the chainstay (which is effectively what it is) weakens it structutally in an area where a lot of torque is transmitted.

Narrower tires is the answer to the question.


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## andulong (Nov 23, 2006)

cyclust said:


> I'd say your chance od success is roughly equal to your chance of ruining your frame. I'd simply use a slightly smaller tire and live with it.



+1...I say go with what you have, get a narrower tire for the rear and keep the extra tire as a spare for up front.


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## SilentAssassin (Jul 29, 2010)

Mike Prince said:


> Plus what the painter would charge to repaint the modified area as the paint would at least crack in that area. There's really no good way to do this by tweaking the frame IMO. Best case is that the bashing in of the chainstay (which is effectively what it is) weakens it structutally in an area where a lot of torque is transmitted.
> 
> Narrower tires is the answer to the question.


People add dimples to get clearance all the time after the bike has been built, usually from what I've read, they would do it to get crank clearance.

Also I don't care about the paint cracking. I'd probably just put touch up paint over the area. This is a commuter bike that will see a lot of miles, and it was also bought used.

I've also read about people taking their bikes to a frame builder to have this done.


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## Mike Prince (Jan 30, 2004)

SilentAssassin said:


> People add dimples to get clearance all the time after the bike has been built, usually from what I've read, they would do it to get crank clearance.
> 
> Also I don't care about the paint cracking. I'd probably just put touch up paint over the area. This is a commuter bike that will see a lot of miles, and it was also bought used.
> 
> I've also read about people taking their bikes to a frame builder to have this done.


Have you actually talked to a framebuilder about it or just read anecdotal stories online? There's a few folks on here who build, I would shoot Ed ("Nessism") a PM and get his advice before I took any of the random advice (including mine) that you have received in this thread,


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## krisdrum (Oct 29, 2007)

Steel or aluminum frame? Steel, your mod is likely achieveable. Alum, it wouldn't be recommended.


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## JCavilia (Sep 12, 2005)

SilentAssassin said:


> People add dimples to get clearance all the time after the bike has been built, usually from what I've read, they would do it to get crank clearance.
> 
> I've also read about people taking their bikes to a frame builder to have this done.


Didn't know that. Good luck. Please let us know how it works out.


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## SilentAssassin (Jul 29, 2010)

Mike Prince said:


> Have you actually talked to a framebuilder about it or just read anecdotal stories online? There's a few folks on here who build, I would shoot Ed ("Nessism") a PM and get his advice before I took any of the random advice (including mine) that you have received in this thread,


Thanks, I'll shoot him a PM.


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## SilentAssassin (Jul 29, 2010)

krisdrum,

It's a steel frame.


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## FBinNY (Jan 24, 2009)

You didn't say what tire width you were trying to use, but if there's any downside room in tire width, it's a no brainer. *Use a tire that fits, and leave the frame alone.
*
As someone else pointed out chainstay crimping is done prior to building, and while it isn't hard to deepen an existing crimp, adding one to a non crimped oval tube isn't nearly as easy.

You might find a builder to take this on, but it won't be cheap. so if you're dead set on these wide tires, you'd be better off selling this frame and buying one more suited to your needs.


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## SilentAssassin (Jul 29, 2010)

double post


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## SilentAssassin (Jul 29, 2010)

I'm asking around. Not going to pay an arm and a leg to have this done obviously. I know an experienced frame builder could probably do this real quickly with the right tools. Tire size I want to use is in the picture: it's a 700x45 tire.


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## SilentAssassin (Jul 29, 2010)

FBinNY said:


> You didn't say what tire width you were trying to use, but if there's any downside room in tire width, it's a no brainer. *Use a tire that fits, and leave the frame alone.
> *
> As someone else pointed out chainstay crimping is done prior to building, and while it isn't hard to deepen an existing crimp, adding one to a non crimped oval tube isn't nearly as easy.
> 
> You might find a builder to take this on, but it won't be cheap. so if you're dead set on these wide tires, you'd be better off selling this frame and buying one more suited to your needs.


People seem to use a c-clamp, and a wood block to protect the other side of the frame when they do it.


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## wim (Feb 28, 2005)

SilentAssassin said:


> People seem to use a c-clamp, and a wood block to protect the other side of the frame when they do it.


Little late to the party, but dimpling (we called it "thumping" a frame) was pretty common back in the day. When a rider wanted to try a huge chainring on the track and there was insufficient chainstay clearance, an educated thwack or two with plastic or wooden mallet would do the trick, with no problems other than a paint flake or two after the deed. Of course, bicycles weren't living room wall art back in those days.

However, this was in the days of stout steel tubing—long before there was EL and OS. My suggestion is to go ahead and dimple with with the clamp and wood if the tubing is traditional thick-walled steel like 4130 gas pipe or even something like Reynolds 500-series tubing. But if your frame is made to compete with aluminum- or carbon frames in terms of weight, I'd take the general advice given in this thread and not do it.


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## PdxMark (Feb 3, 2004)

SilentAssassin said:


> I'm asking around. Not going to pay an arm and a leg to have this done obviously. I know an experienced frame builder could probably do this real quickly with the right tools. Tire size I want to use is in the picture: it's a 700x45 tire.


What is the road or riding situation that requires a 700x45 tire over a 700x35?


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## SilentAssassin (Jul 29, 2010)

wim, it's 4130 according to the 4130 label on the frame. It definitely seems to weigh as much as a tank.


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## SilentAssassin (Jul 29, 2010)

PdxMark said:


> What is the road or riding situation that requires a 700x45 tire over a 700x35?


More of a case of want than require.


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## martinrjensen (Sep 23, 2007)

(OK, here's the witty comment):
WTF????[insert witty comment here [/quote]


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## SilentAssassin (Jul 29, 2010)

Mootsie said:



> Cut a mm out of each dropout. It will move the tire back to give you the space you desire.


This seems like it would actually work. Just file it down 1mm?


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## PdxMark (Feb 3, 2004)

SilentAssassin said:


> This seems like it would actually work. Just file it down 1mm?


Are they horizontal dropouts?


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## SilentAssassin (Jul 29, 2010)

Yah, they are horizontal. Seems like the only thing this would affect possibly is chain length?


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## wim (Feb 28, 2005)

SilentAssassin said:


> wim, it's 4130 according to the 4130 label on the frame. It definitely seems to weigh as much as a tank.


Well, here's a popular 4130 frame that's been severely factory-dimpled (more like flattened) so that fat tires fit fine. This frame's been going strong for a number of years now. But as said, do it carefully and keep the stress off the welds.


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## SilentAssassin (Jul 29, 2010)

The tubing on those chainstays seem very large however compared to mine. I definitely don't think mine would have to be dimpled that severely.


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## wim (Feb 28, 2005)

SilentAssassin said:


> The tubing on those chainstays seem very large however compared to mine. I definitely don't think mine would have to be dimpled that severely.


In the area of the chainstay bridge, the short axis of the oval tubing in the photo is 17 mm outside diameter. The most severe dimple brings that down to about 9 mm. But keep in mind that this is a double-sided dimple to also increase chainring clearance.

/w


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## Mel Erickson (Feb 3, 2004)

SilentAssassin said:


> This seems like it would actually work. Just file it down 1mm?


Is your wheel all the way to the rear of the dropouts? If not, you could move it back without even having to file. You might have to lengthen the chain, but probably not. Otherwise, you could probably file even more than 1mm if necessary. Just get a rat tail file and file away. There's not doubt plenty of material in the dropouts if this is a 4130 frame.


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## SilentAssassin (Jul 29, 2010)

Alright wim. There is a guy locally that can do the job for a fair price it seems. They seem like a good shop. Rather get this done and be able to use my existing tires. Oh what do you guys suggest as how much clearance I should have from the tire to the chainstay? About 5mm you think?


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## Mootsie (Feb 4, 2004)

martinrjensen said:


> (OK, here's the witty comment):
> WTF????[insert witty comment here
> You obviously have never had a bike with horizontal drop outs. Same principle. You move the wheel back to gain wheel cleareance, Mr smarty pants.


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## Mootsie (Feb 4, 2004)

SilentAssassin said:


> This seems like it would actually work. Just file it down 1mm?


File = lots of work. Find a buddy with a Dremel tool.


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## Mootsie (Feb 4, 2004)

SilentAssassin said:


> Yah, they are horizontal. Seems like the only thing this would affect possibly is chain length?


OMG, if they are horizontal, your answer is minutes away. Get to it buddy boy.


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## Mootsie (Feb 4, 2004)

SilentAssassin said:


> Alright wim. There is a guy locally that can do the job for a fair price it seems. They seem like a good shop. Rather get this done and be able to use my existing tires. Oh what do you guys suggest as how much clearance I should have from the tire to the chainstay? About 5mm you think?


Keep the wheel reasonably true and you'll be fine with less than that.


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## SilentAssassin (Jul 29, 2010)

Mel Erickson said:


> Is your wheel all the way to the rear of the dropouts? If not, you could move it back without even having to file. You might have to lengthen the chain, but probably not. Otherwise, you could probably file even more than 1mm if necessary. Just get a rat tail file and file away. There's not doubt plenty of material in the dropouts if this is a 4130 frame.


Yah, I kind of like the tire to stay forward as much as possible. Just going to get the dimples done tomorrow.


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## wim (Feb 28, 2005)

SilentAssassin said:


> About 5mm you think?


5 mm clearance per side is plenty. Just keep in mind that nominal sizing of tires often has nothing to do with reality. So while one tire maker's 45-622 (or 700x45) might fit fine with the extra clearance, someone else's _nominally_ 45-mm tire might not.


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## Mel Erickson (Feb 3, 2004)

SilentAssassin said:


> Yah, I kind of like the tire to stay forward as much as possible. Just going to get the dimples done tomorrow.


What? Why is the tire being forward a concern?


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## SilentAssassin (Jul 29, 2010)

Yah, decided to use the c-clamp method and just do it myself. Just did one side, but now I got to take the crank off to do the other. Tricky part was just finding the right piece of metal to create the dimple.


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## Mike Prince (Jan 30, 2004)

Once you are done, please post pictures. Curious to see what the final result looks like.


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## SilentAssassin (Jul 29, 2010)

Done both sides. Turned out good. Got the clearance. I used a strange long piece of metal I had. Even with the wheel slightly out of true it will not rub. Saved myself $40 it seems. I could probably run some decent mtb tires on this thing. Now I plan to rebuild both wheels with some DT Swiss Champion spokes...well...down the line when the next holiday weekend comes around. Will shoot back with a nice easy 30 miler ride report soon.


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## andulong (Nov 23, 2006)

I said something not so nice and had to change it.....


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## SilentAssassin (Jul 29, 2010)

Mootsie said:


> OMG, if they are horizontal, your answer is minutes away. Get to it buddy boy.


Was debating on this but creating dimples was much faster and easier I think. Also it keeps the chain length to spec.


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## SilentAssassin (Jul 29, 2010)

andulong said:


> I said something not so nice and had to change it.....


Hey don't troll my thread :blush2:


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## SilentAssassin (Jul 29, 2010)

Mel Erickson said:


> What? Why is the tire being forward a concern?


Chain length. In the end, filing would of been more work, plus money for a dremel that I don't need. Creating dimples was free and arguably, faster anyways.


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