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New D/A crossover gear chain rub(7 posts)

New D/A crossover gear chain rubtwikkie
Mar 15, 2002 11:27 PM
Wat is up with my new drivetrain? LBS installed Crankset, and Ultegra BB, as well as cassette. When I am in my small chainring, the 11-12-13 cogs areimpossible to use cos of annoying chainrub. Is this a result of Shimano moving the small ring in towards the big ring? If so, it is a flawed design. LBS says it is not my chainline...what the heck!

Also--front der (Sora braze on) cannot, it seems, clear the big ring, even in its highest position, therefore rendering the big ring useless. If you've been paying attention, you'll have realized that I've now 6 useable gears! This F$#%@!* sucks! help!
You have a mis-mash of parts.Spoke Wrench
Mar 16, 2002 5:29 AM
This is the kind of makeover that I don't mind messing with on one of my own bikes, but I refuse to do on a customer's bike. Why? Because all of the mis-matched bits and pieces never seem to work to my satisfaction the first time. It often takes a second shot at ordering the right parts and it takes about two or three times as much time as the customer is willing to pay for.

So what are you trying to accomplish? How'd you acquire this combination of parts? Sticking a DA crank on a Sora equipped bike seems a little curious to me. If you are looking for performance, it sounds to me like the original Sora drivetrain actually worked better. If you are looking for style, just sticking a DA crank on a Sora bike isn't really going to make it anyway.
You have a mis-mash of parts.twikkie
Mar 16, 2002 12:15 PM
actually...it isn't exactly a mish-mash of parts. Only the frnt der is sora. Everything else is either D/A (crankset, rear der) or ultegra (bb, shifter/levers, brakeset, and 105 hubset). It is not a matter of looking for style, but looking for lighter, more durable components. Understand that I didn't simply '"stick a DA crankset on a Sora equipped bike."

The problem actually turned out to be that the hangar did not accept a high enough position for a 53 tooth large ring.

thanks for input though, I appreciate it.
re: New D/A crossover gear chain rubDrD
Mar 16, 2002 7:51 AM
Odd component mix - but be that as it may, it sounds like it could be a couple of things - first, I am assuming you have a double setup - in that case, either they installed the wrong bottom bracket (spindle too long) which prevents the front der. from reaching the large chainring, or they installed the cranks improperly on the bottom bracket (so that the splined aren't engaged - I would check that out, as you can destroy an expensive crankset in short order if that is the case) or the limit screws on the front der. need to be adjusted to allow the front der. to reach out over the large chainring (the same thing would happen if the cable were really loose, too - how slack is it when you are on the small ring up front?)

Make sure it's not something obvious (i.e., front der. cage too low so that it hits the large chainring)

If an LBS let you purchase that crankset and BB from them, then installed it for you, giving you the bike back with only 6 gears useable, I would strongly recommend going elsewhere - they aren't too competent...
Doh!DrD
Mar 16, 2002 10:32 AM
Obviously it's not the bottom bracket... a longer spindle would help reach the outer ring, rather than hurt! (oops!)
re: New D/A crossover gear chain rubtwikkie
Mar 16, 2002 12:17 PM
thanks for the help.
Double check the chain lineKerry
Mar 16, 2002 5:20 PM
You don't need an LBS to tell you whether your chain line is good. The center of the front chain rings should be lined up with the middle cog in the back. You can easily check this with a long straight edge. Check from the large chain ring and the small - the center between those two should be the center of the cassette. If you are telling us that the chain rub is against the large chain ring, then it is hard to imagine that your chain line is right. If the rub is on that funky front derailleur, you can probably guess the recommendation on that thing. Also, losing that 11 (and most likely the 12) would make things a tiny bit better. Do you really need these cogs?