Tuesday, May 03, 2005

Hollowtech II Cranks

To build up my Turner I needed a complete set of components and investigating the crankset's it appeared that the Shimano Hollowtech II system was getting good reviews. The externally mounted bearings were reported to be stiff and much longer lived that the rival ISIS range. As I'd had no problems with the earlier Octalink system which also used hollow arms, I thought I'd give it a try.

When I opened Chaybo's parcel I was surprised to see how the system works. It doesn't have a traditional / separate bottom bracket, as the hollow spindle is fixed to the crank rings. The bearings are individual cups which snug up to the bb shell on the frame, needing a special tool (Park BBT-9 - which was much cheaper to source from the US of A). Once the bearings are in place you pass the spindle through, mount the splined, non drive side arm, snug up finger tight with the center spinner and finally clamp it all tight with two opposing 5mm allen bolts. To account for different width bb shells the system comes with three plastic shims which I initially left in the toolbox.

Update: In use the system appears to be plenty stiff enough for my paltry legs and after some 9 months and 1,200 miles+ the bearings are stiff smooth and tight. After a few months running, Rob had a look and added a spacer to the driveside which has helped the front mech (which was bent!) acquire a much cleaner up shift.

If you do have any issues with the bearings, Enduro Fork Seals have recently introduced a placement bearings kit for X-type / outboard BB cranksets which looks like it should be more durable.


Farqui said...

On a ride last wk I experienced some nasty graunching and I thought my bb was on the way out. It seemed logical cause 'cos its had some 18 months of continuous abuse and clocked almost 2k miles.

So I popped off the cranks and thought that both bearings were a little notchy but not as bad as expected.

Numerous threads on the www had illustrated that it is possible to clean/regrease these non-service bearings. So I decided to give mine a try.

Much to my surprise there was plenty of the original grease within the races so they were simply cleaned, regreased and reassembled.

The notchyness appears to have been caused by some grit that had sneaked in behind the outer plastic covers. A point to note in the future me thinks.

PS: On a related note, checkout Peter Verdone's interesting thoughts on the Shimano and Raceface X-Type bearings.