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Chainrings(3 posts)

Jan 21, 2002 3:36 PM
I was wondering about some new chainring/crank combinations. I'm looking to change the 52/42/30 chainrings with sora cranks and bb to a 55/42. I know the 55 chainring has to be dura-ace, and I want to upgrade the cranks as well. Can I run a 105 crank on the sora bb with a dura-ace 55 chainring and sora 42? Or do I need to get ultegra cranks? Or different chainrings? Any recommendations would be greatly appreciated.

"Trees don't move."
re: Chainringsgrzy
Jan 21, 2002 4:30 PM
Looks like the 55 is only available in DA as part of the triathlon spec. with a 42 also listed for tris. If the BCD's match then you have a chance - assuming they didn't do something with the offset (ala XT stuff). I know you can run DA rings on Ultegra and use either a DA/Ultegra/105 BB. I know you're trying to probably save money, but you can get an Ultegra crank (w/rings) for around $110 on sale. However you will probably have to special order the 55 CR and it won't be cheap. If you add up the costs you might find that it comes close to ordering the DA crank and CR the way you want it. You could also consider all of the other after market CR suppliers. As far as things working with Sora I don't know. I assume you're running a 650 wheel bike and that is why you want the 55T. Otherwise you could run an 11T cog set and combined with a 52 that should get you up to 50+ mph w/out an excessive cadence. Of course I could be all wet.
Bottom bracketnee Spoke Wrench
Jan 21, 2002 5:45 PM
The bottom bracket that you have won't work. The Sora bottom bracket has a square taper spindle. All of the upper end Shimano stuff for the last couple of years has used splined botom brackets. The spindle is going to be too wide also since you are replacing a triple with a double chainring crankset.