Would you run a chainring this close to the chainstay?
#27
Senior Member
Join Date: Oct 2013
Location: Mich
Posts: 7,572
Bikes: RSO E-tire dropper fixie brifter
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 3,125 Times
in
1,987 Posts
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.
__________________
-Oh Hey!
-Oh Hey!
Likes For Troul:
#28
Senior Member
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.
Likes For Joe Remi:
#30
Tinker-er
Join Date: Oct 2007
Location: Mid-Atlantic
Posts: 504
Bikes: 1956 Rudge Sports; 1983 Univega Alpina Uno; 1981 Miyata 610; 1973 Raleigh Twenty; 1994 Breezer Lightning XTR; V4 Yuba Mundo aka "The Schlepper"; 1987 Raleigh "The Edge" Mountain Trials; 1952 R.O. Harrison "Madison"
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 185 Post(s)
Liked 317 Times
in
209 Posts
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.
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.
Likes For PhilFo:
#31
Senior Member
Join Date: Feb 2017
Location: Northern Shenandoah Valley
Posts: 4,143
Bikes: More bikes than riders
Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 1446 Post(s)
Liked 766 Times
in
572 Posts
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.
#32
Senior Member
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 27,549
Mentioned: 217 Post(s)
Tagged: 0 Thread(s)
Quoted: 18446 Post(s)
Liked 4,557 Times
in
3,386 Posts
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.
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.
#33
Senior Member
#34
Newbie
#36
Full Member
Thread Starter
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.
#37
Full Member
Thread Starter
Never thought of that. I'll give this a try once it's together.
#38
Full Member
Thread Starter
The gap is actually UNDER 2mm. Just barely under 2mm.
#39
Advanced Slacker
Join Date: Feb 2017
Posts: 6,224
Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2768 Post(s)
Liked 2,546 Times
in
1,437 Posts
#41
Senior Member
Join Date: Apr 2016
Posts: 1,411
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 559 Post(s)
Liked 501 Times
in
382 Posts
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 ...
#43
Full Member
Thread Starter
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.