Shorter Chainstays causing more shifting noise/cross? Moots/Campy SR 11

[happycampyer]

The problem wouldn't be as bad if the tallest cog were a 25. The frame is built with a racing geometry and was designed for racing gearing (and racing tires, etc.). The noise is the chain's not so subtle way of telling you that it's under duress.

[Mzilliox]

so did the new chain arrive in time? i feel semi validated that i didn;t have an easy time of it now. but like most say, you rarely actually use that gear. i know thats not what you want to hear though with a new bike. also, as someone mentioned. the bike is designed as a race bike but you are asking a bit more of it. perhaps the design factor does play into it.

[shovelhd]

My Felt has 405mm chainstays and makes noise in the 52/28. What everyone else said. Don't use it unless you're in a racing situation and don't want to risk a front derailleur shift.

[PNW]

Thanks for all of the info and help. I won't ever be using the gear it was just a reference point in getting the shifting dialed in. The RD was being pulled forward a lot and the chain was too short by a link. I won't ever be using a 50/28 or a 50/29. The mechanic said he has everything fixed and it's shifting wonderfully but the top four biggest cogs with the 50 there is a "bit" more noise which is obviously the cross chaining. I'll be getting my fit done today and will see it in person to give you guys a reference with photos.


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[Mark McM]

Originally Posted by chiasticon

only bike I've ever had with 405mm chainstays (a Gaulzetti Corsa) did the same thing when in big-big, using 11 speed Ultegra di2. research into the issue basically said the short chainstays were the problem. I didn't keep the bike long enough to try and figure it out.

Jumping to a conclusion and immediately blaming chainstay length ignores basic geometry. It is true that shortening the chainstay length increases the chain deflection angle, but many other variables have a bigger effect on chain deflection angle. For example, shortening the chainstays by 10 mm (about 2.4%) has about the same affect chain angle as offsetting the cassette or cranks by 0.5 mm (which is possible less than the manufacturing tolerances on frames and freehubs). You'd have the shorten the chainstays by a lot before it made a significant difference in chain deflection angle.

[carpediemracing]

Originally Posted by PNW

Thanks for all of the info and help. I won't ever be using the gear it was just a reference point in getting the shifting dialed in. The RD was being pulled forward a lot and the chain was too short by a link. I won't ever be using a 50/28 or a 50/29. The mechanic said he has everything fixed and it's shifting wonderfully but the top four biggest cogs with the 50 there is a "bit" more noise which is obviously the cross chaining. I'll be getting my fit done today and will see it in person to give you guys a reference with photos.


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I have 39 cm stays on my bikes, and I basically refuse to shift into the small ring when I race, therefore on any kind of a hill if I'm struggling I'll be in the big-big. I run a 53/39, 11-23 or 11-25.

With shorter stays and using the big ring you really want to lean toward the longer side as far as chain length goes. I do the longest chain I can use in the 39x11 without losing tension in the chain.

I recently put on a new chain (DA, on an otherwise Record/Chorus 10s set up) and I was pleasantly surprised at how quiet the chain was. The old chain was a worn Record chain.

[kramnnim]

39cm stays, is your seat tube curved to make room for the tire? :O

[stien]

It's a cutout.

[ultraman6970]

Is not a problem with campagnolo IMO, it is a bad habit problem, if you want to use 50x28 with a short cage RD... isnt more efficient just go 34x ???

50x28 and 43x19 is the same gear... and the op wont have the problem anymore.

Second option, buy a long cage rd and a new chain... depending on the group we are talking 300 bucks right there. Cheaper to learn learn how to get rid off the bad habits of chain crossing.

I do get that 50x28 is super light, easy to move because the 28 has a lot or torque in it, but the 19 isnt that bad either and gives you the advantage to have like 4 more cogs bigger than the 19 in case you are running off gas... the other problem crossing chain like a maniac is that you put way too much stress in the chain, rd and chainrings, after a few months that chain is gonzo... and needs to be swapped.

That you can do something doesnt mean is the right thing to do.... btw with a longer chain stay the problem you get is that if you cross 34x11 the chain almost certain will touch the big chanring. Crosschain is not a good habit to be honest with you.

Good luck in this one

[carpediemracing]

Originally Posted by kramnnim

39cm stays, is your seat tube curved to make room for the tire? :O

39.0 cut out (aero type alum tubeset)

39.3 regular round alum tubing (downtube is ovalized). Builder thought 39.3 was minimum length for this one, probably could have done 39.0 but tire would be close to seat tube.

[justaute]

I apologize in advance for tangentially re-directing the topic a bit.

How does everyone measure chainstay length? Is it...
- Method 1 (chainstay?): direct measurement from center-of-BB to center-of-dropout
- Method 2 (Rear-center?): An effective line that is parallel to the ground (between to parallel lines through both center-of-BB & center-of-dropout)

Thanks.

[carpediemracing]

I measured from center BB to center of quick release skewer.