SRAM X Glide cassette and DuraAce mech

[robgul]

I've been asked to look at a friend's bike which is having issues with gears . . .

The bike is a Trek "Discovery Channel" replica* so must be around 2006/7 - most of it is original with DuraAce shifters and mechs (front is a triple) from the period (the rear mech is a bit floppy but I don't think that's the problem)

The bike was running with a Shimano 11-36 cassette and gear changes were fine from smallest to largest rear sprocket - BUT the wheel rim was a bit iffy. 

Someone gave him a replacement wheel that had a SRAM X-Glide 11-36 cassette already fitted (the version that has a couple of loose small sprockets at the small end and the remainder of the block is machined from one chink of metal)

Using the donor wheel and the SRAM cassette, with the mechs appearing to be set up correctly it wont get into either the large chainring/smallest sprocket or small chainring/largest sprocket - and of the intermediate options some are fine, some are rattly.

I'm going to try re-fitting the Shimano cassette to the donor wheel and see what happens .  ..... BUT I'm intrigued as to why the issues with the SRAM cassette  (both cassettes test as being unworn with a Rolhof checker)

Could the old DuraAce shifters and/or rear mech be incompatible with the SRAM cassette?  - or any other ideas.


* trivia: the bike was one of about 10 given by Trek to a group that rode the TdeF either the day before or the day after, I can't remember which, the actual race in, I think, 2007.

[zigzag]

a photo would be helpful. dura ace rear mech (esp. of that vintage) was not designed to shift 36t cassette so there might have been some alterations?

[LittleWheelsandBig]

10 speed, right? Should be the same cog spacing. There is something odd going on with cassette size, as ZZ noted.

[robgul]

10 speed, right? Should be the same cog spacing. There is something odd going on with cassette size, as ZZ noted.

Yep - 10 speed - agreed the mech/cassette is at the extreme with B-screw fully in - chain length checked and that's correct for the big/big chainring/sprocket combo BUT it used to work with the Shimano 36 and doesn't with the SRAM.    Both cassettes have spent an hour in the ultrasonic bath to get them really clean - and ready to try the Shimano on the new wheel tomorrow.

I shall report back

[LittleWheelsandBig]

SRAM cassettes have a reputation for not shifting quite as well as Shimano. That marginal difference might be enough when the derailleur is being pushed so far past its limits.

[robgul]

UPDATE - fitted the Shimano cassette - rode a couple of miles around the streets with some modest slopes - engaged smallest chainring and largest sprocket, ditto vice versa.  Changes were a little clunky but I'm sure that's down to wear/old age on the shifters and derailleurs.  Very strange - having said that I'm not convinced that the rider's technique for use of gears and changes is that good.

Thanks for the thoughts.