0

Will a Shimano Dura-Ace 9000 55-42T crankset be compatible with my current Shimano 8 speed 11-28T cassette?

The purpose of this change is for Time Trialling.

  • 3
    Did you already buy the 55/42? Tour de France-level pro's ride 53/39 for the most part, and I suspect you're not that strong. Heck, Alberto Contador was known to use a compact 50/34 at times. Nevermind pairing a 55/42 with an 11-28 cassette seems counterproductive. – Andrew Henle Jul 16 '19 at 15:48
  • 1
    A 55-tooth chainring when on the 11-tooth cog means a mere 80 rpm puts you over 30 mph/50 kph. I hope you're not thinking a bigger crankset makes you faster. – Andrew Henle Jul 16 '19 at 15:58
  • 6
    An 8 speed drivetrain is either cheap or old, why put Shimano's most expensive crank on that? – Argenti Apparatus Jul 16 '19 at 16:29
  • @AndrewHenle I believe this has been discussed before, but drivetrain efficiency drops with cogs smaller than 14t. These chainrings are intended to used at time trial speeds with 14-16t cog. Of course, 11-28 isn't exactly time trial stuff. – ojs Jul 16 '19 at 18:34
  • 1
    WashichawbachaW, you're coming across as very aggressive. @AndrewHenle offered you perfectly reasonable advice. All you had to do was say that thanks, you're aware of that and you intend to use the bike for time trialling. – David Richerby Jul 17 '19 at 21:35
3

If you ask shimano, they will say this won't work. But in my experience with 11spd cranks and 9 speed chain cogsets, it always works well enough. I've never had any significant problems using an 11spd crankset with 9 speed chain and 9 speed front derailleurs.

The difference between 8/9/10/11 speed chain is the external width, not the internal size. The only difference between an "11" speed crank and an "8" speed crank is a slight narrowing of the spacing between the chainrings so that the narrower 11 speed chain won't fall in between. The dimensions of the chainrings are the same since they all have the same internal width. I would not expect any problems using that crank with 8 spd that can't be solved by switching to a 9 or 10 speed chain.

The biggest problem you will have is likely getting the derailleur high enough to clear a 55t chainring. If you have a frame mount derailleur, most of those will only go up to a 53t without grinding the derailleur mount.

You should be able to use that crankset with an 8 speed cogset. If you do run into issues with the chain angle rubbing in the small/small gear, you can try using a "smaller" chain (i.e.) 9 or 10 speed.

  • If you just want a 55t chain ring, it'd be a lot cheaper just to buy that than an all new crankset. If you've got a standard 135 BCD crank, you can get a 55t "time trial" chainring for about $80 bucks. – Fred the Magic Wonder Dog Jul 17 '19 at 20:11
  • Well that's a good answer from someone who have experience similarly to what I asked. I also asked some people and they said it could be done. I just clamp the derailleur no problem. Thank you for your answer and for not judging. – WashichawbachaW Jul 18 '19 at 9:11
  • @Fred_the_Magic_Wonder_Dog thank you for the advise but I'm also buying that specific model because of style. – WashichawbachaW Jul 18 '19 at 11:07
5

Nominally no, an 11 speed speed crank will not work with an 8 speed drivetrain.

As the number of speeds (number of cassette sprockets) increased as new groupsets were released, the sprockets were narrowed and moved closer together. The outside width of the chain was also progressively narrowed so that they worked with the narrower sprocket spacing. This also meant that crank chainrings had to be moved closer together. An 8 speed front derailleur and chain will not shift at all well on a 11 speed crank.

Other things you should bear in mind if you are serious about a 55/42 crank. You may not have enough chainstay clearance for the bigger rings, and you will need to check that your front derailleur will move up enough - some braze-on clamps don't have enough adjustment.

  • Have you tried it yourself or seen someone used that combination and didn't work? There is no problem with my derailleur. I can manage. – WashichawbachaW Jul 18 '19 at 11:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.