|Ultegra 39-53 chain rub - but what about DA?||Ping_Pong|
Jul 22, 2002 5:03 AM
|Yes, I have read the archives on this...
I agonised over a dura-ace crank for weeks and went Ultegra to save cash only to get this rub on the 53 from my 13,14 and 15 cogs (Bianchi Pro-L 1999).
Please tell me DA is the same in this regard.
Please don't tell me I shouldn't be using 39-15.
Please don't mention derailleurs.
|I'll try not to use the "d" word.||Quack|
Jul 22, 2002 5:54 AM
|You may have to increase the limit of your front thingamajig so that the ratchet in your lever can fully engage and doesn't drop back down to the next setting, allowing the rub to occur. I usually adjust mine so that I get somewhat heavy rub while crosschaining with the 53-top cog and things seem to work out OK in the 53-12. Just keep in mind that increasing the limit too much can cause your chain to shoot right over the top of the big ring.
|re: Ultegra 39-53 chain rub - but what about DA?||da cyclist|
Jul 22, 2002 6:00 AM
|Is the chain rubbing the derailleur or is it rubbing on the chainring? If it the derailleur, then you just need to adjust it. If it the chainring, then you have chainline issue that is only going to be fixed with a different bottom bracket.|
|re: Ultegra 39-53 chain rub - but what about DA?||Chen2|
Jul 22, 2002 6:09 AM
|If it is the chain rubbing the big ring, I saw a post somewhere that this is a common problem with Ultegra and that there is a spacer washer available to correct the chainline. Another way it can happen is if the inside ring is mounted backwards. The "39" stamping should face the bike frame (I think). At least that's the way it is with the older Ultegras. The "53" should face out to the right. A reversed ring will screw up the spacing.
|re: Happens on D/A too...||Mike Prince|
Jul 22, 2002 6:36 AM
|As Al mentioned the easy fix is a small (2 mm or so) spacer installed between the right cup and the BB shell. For the most part, this will fix the chain rubbing on the big ring problem. Don't overdo it (push it out too far) though, or the performance on the larger cogs can suffer.
Another approach is an XTR BB. Spindle length is 112 mm, 2.5 mm longer than DA/Ult doubles and compatible spline pattern. But the spacer works just as well and is a hell of a lot cheaper.
For what it's worth, depending on your frame geometry and chainstay length, you probably will not be able to eliminate all of the interference. 39/13 should not be an issue as this is an extreme crosschain combo, but you may get intermittent rubbing on the 39/14 as the BB flexes under load. In a workstand it probably will not rub. 39/15 should be quieter post-spacer.
|re: Ultegra 39-53 chain rub - but what about DA?||davet|
Jul 22, 2002 3:57 PM
|IF your front d** is properly adjusted, and every thing else on your bike is as it should be and you are still getting chain rub on the big ring when cross chained, that is a function of the length of your chainstays and would happen on a similar Dura-Ace set up. A bike with short chainstays forces a larger angle of departure for the chain when cross chained. A bike with longer chainstays has a smaller angle of departure for the chain and no chain rub. The easiest way for you to correct your chainrub is to remove your bottom bracket and install a 1mm spacer between the frame and drive side BB cup. This should space your crankset enough to the right to eliminate the chainrub. The spacer should be available at your LBS for little $.|
|DA will be the same||weiwentg|
Jul 22, 2002 11:13 PM
|are you quite sure the chain is rubbing the chainring, and not the derailleur cage? mine does rub the cage in the 13 and 14t, and the chainring in the 12t. that's what the trim function is for.
probably just get the spacer. yes, 39-15 is a useful gear (as is 39-14).