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Would you run a chainring this close to the chainstay?

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Would you run a chainring this close to the chainstay?

Old 02-24-23, 02:49 PM
  #26  
Fredo76
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So far, so good, on mine:


We have clearance, Clarence!
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Old 02-24-23, 07:12 PM
  #27  
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FWIW; I had a modern sram crankset with sram BB that had about the same gap as the OP. It "walked" just enough to grind a quarter moon into the chainstay. It didn't take much. It was a new frame too.
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Old 02-24-23, 10:51 PM
  #28  
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Originally Posted by Troul
FWIW; I had a modern sram crankset with sram BB that had about the same gap as the OP. It "walked" just enough to grind a quarter moon into the chainstay. It didn't take much. It was a new frame too.
This is what I'm saying. In spite of all the detractors telling me I got it wrong, I wouldn't ride that bike with that clearance.
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Old 02-25-23, 07:36 AM
  #29  
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OP: How's the chainline look?
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Old 02-28-23, 06:23 AM
  #30  
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You're more likely to have a crank spider arm or chainring bent enough to contact the frame, than the frame itself bending that much.
I ran my chainrings close to the stay on my old Vitus 979, which was like a springy piece of penne pasta, and the small ring never contacted the stay.
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Old 02-28-23, 07:42 AM
  #31  
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mrmb if you're asking about it, I presume it's because you're concerned about the paintwork. No judgement here...I would be also. I guess I'd ask myself what the costs are in just spacing the chainring over a little bit. I think someone suggested gaining a mil or two with a crank spacer, or even a slightly longer spindle. I understand the concern about Q-factor, but I don't think your legs, knees, or body will notice an extra couple of millimeters (my fat bike has a 168mm spindle in a 100mm bottom bracket!). I think I'd personally spend the 30 bucks now (or less if you use a thin spacer) to know you won't have any problems in the future.
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Old 03-02-23, 01:52 PM
  #32  
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I think the gap should be fine. The biggest risk is if you drop your chain between that gap, and have to extract it.

I'm trying to remember the mechanics of a trapped chain. It may be that it always happens on the middle/outer ring, and requires a smaller ring to pull the chain through.

In that case, it won't happen with the close small ring.



Perhaps what I'm thinking about is "Chain Suck".


Again, that may be more an interaction with outer rings than something that regularly happens with the inner ring.

Last edited by CliffordK; 03-02-23 at 01:57 PM.
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Old 03-02-23, 02:52 PM
  #33  
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Originally Posted by mitchmellow62
OP: How's the chainline look?
I think the OP gave up on us weeks ago.
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Old 03-12-23, 03:56 PM
  #34  
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Originally Posted by mrmb
Just under 2mm
Would you run this?
Why not? Enough space.
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Old 03-12-23, 09:10 PM
  #35  
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Originally Posted by mitchmellow62
OP: How's the chainline look?
Chainline is spot on.
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Old 03-12-23, 09:14 PM
  #36  
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Originally Posted by hokiefyd
mrmb if you're asking about it, I presume it's because you're concerned about the paintwork. No judgement here...I would be also. I guess I'd ask myself what the costs are in just spacing the chainring over a little bit. I think someone suggested gaining a mil or two with a crank spacer, or even a slightly longer spindle. I understand the concern about Q-factor, but I don't think your legs, knees, or body will notice an extra couple of millimeters (my fat bike has a 168mm spindle in a 100mm bottom bracket!). I think I'd personally spend the 30 bucks now (or less if you use a thin spacer) to know you won't have any problems in the future.
Yes, paintwork. And scuffing the chromemoly. Moving the chainring means losing my perfect chainline. My only real option here is to use a smaller chainring. But then that means a different cog too in order to keep my gear ratio. I will give this a go as is. Still need to true and tension the wheels, so not quite up and running yet.
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Old 03-12-23, 09:15 PM
  #37  
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Originally Posted by icemilkcoffee
Very easy way to test. push the front wheel into a wall corner. Put all your weight on the right pedal and bounce up and down and see if anything touches. I bet nothing touches. The chain stays will pretty much flex together with the BB.
Never thought of that. I'll give this a try once it's together.
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Old 03-12-23, 09:16 PM
  #38  
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Originally Posted by Kapusta
Count me among those having a hard time seeing the frame flexing enough to move the stay over 2mm that close to the BB.

I’ve had really tight clearances in the past (I’d guess 2mm) and never had them gouge.
It's not over 2mm.

The gap is actually UNDER 2mm. Just barely under 2mm.
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Old 03-13-23, 05:24 AM
  #39  
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Originally Posted by mrmb
It's not over 2mm.

The gap is actually UNDER 2mm. Just barely under 2mm.
By “over” I mean “over toward the chain ring” not “more than 2mm”.
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Old 03-14-23, 08:12 AM
  #40  
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No problem; I ran a custom steel SS cruiser with less for 20 years.
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Old 03-19-23, 03:29 PM
  #41  
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Originally Posted by freeranger
Looks like I'm in the minority on this one. I wouldn't run it that close and risk scratching up that good looking paint. Why risk scratching it if you don't have to?
The paint wouldn't bother me - after all it will be covered in a layer of dirty chain lube - but creating a stress raiser in the chainstay isn't something I'd want to do if I could reasonably avoid it. Having said that, of course I've dropped chains and chewed up chainstays and they didn't break, but you never know ...
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Old 03-19-23, 08:59 PM
  #42  
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Originally Posted by SurferRosa
Is the chainring steel?
Stainless steel
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Old 03-19-23, 09:02 PM
  #43  
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Originally Posted by icemilkcoffee
Very easy way to test. push the front wheel into a wall corner. Put all your weight on the right pedal and bounce up and down and see if anything touches. I bet nothing touches. The chain stays will pretty much flex together with the BB.
Got it all together and gave this a try today. Since it has low pressure, high volume tires (29 x 2.5 @ 30psi) all that really happened is the tires flexed and distorted some. I couldnt get any visible frame flex.
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