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Converting front crankset from double to triple(4 posts)

Converting front crankset from double to tripleChris Backus
Jun 30, 2001 8:58 PM
Hi-

I am in the process of ordering components to convert my front comps. on my cyclocross bike from a double to a triple set-up. I have ordered a triple Ultegra derailleur and crankset, but am unsure as if I need a new LH shift lever. Right now, the bike has RX100 STI combined brake-gear levers and am unsure if they can accomodate a triple set-up. Any help in this matter would be greatly appreciated. Also, any other words of advice as to this type of transition would be very helpful.

Thanks in Advance-
Chris
Followup ques: Converting front crankset from double to tripleChris Backus
Jun 30, 2001 9:15 PM
In follow-up to my question, additional questions regarding this upgrade. Do I need to change the chain length? To what length? Also, will I need to change the bottom bracket or will the existing one work ok?

Thanks again-
Chris
re: Converting front crankset from double to tripleDrD
Jun 30, 2001 9:56 PM
For the shifter - as far as I know, all levers save Dura Ace work for both doubles and triples.

Chain length - this is generally a function of the largest cog and largest chainring - if they haven't changed, you are fine - if you have a larger combination, you may need to lengthen the chain, and if it's a smaller combination, you may be able to shorten it a link or two.

Other words of advice - you are probably going to need a new bottom bracket, too - triples require a longer spindle than doubles. Also - you may need to change out both the front and rear deraileurs.
re: Converting front crankset from double to tripleRusty Coggs
Jul 1, 2001 8:14 AM
You need the proper splined BB to match the ultegra triple crankset.If your rx-100 shifters were originally setup for a double then they won't shift a triple, as The rx-100 and 105 shifters of that vintage were either double or triple specific. Check under the hoods for a part #,the double was ST-A550. I cannot find a # for a rx-100 triple front,but that does not mean they did not exist. I seem to recall a rx-100 triple front shifter, as that model was essentially the 105 with a different finish.