hollowtech chainsets

tompsk73

Ive just noticed that if I take the hex head nuts off the middle of my crankarms on the hollwtech 2 deore set up Ive got, you can see through the bottom bracket. It is infact, as the name implies, 'hollow'. Do these rather solid and well machined hex head nuts keep the crank arms / chainset on, or are they just dust caps that I can leave off to show off my fancy hollow bottom braket to me mates?!

nicklouse

yes they do hold the cranks on. dont go riding without them.

tompsk73

Cheers louse, did look worryingly empty in there

nicklouse

the LX and XT HR1 had hollow crank bolts so you could look through.

madmole

The XT HT2's are also hollow all the time. With HT2 the crank arms hold the tube through the BB, there are no end caps per see

alfablue

Park Tools web site says:

This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle.

The crank arm is actually secured in place with the two hex-nut pinch bolts on the side of the crank. Once these are secured I think the end cap could be removed, but I personally wouldn't bother.

nicklouse

alfablue wrote:

Park Tools web site says:

This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle.

The crank arm is actually secured in place with the two hex-nut pinch bolts on the side of the crank. Once these are secured I think the end cap could be removed, but I personally wouldn't bother.

YOU TRY IT. the crank arm claps onto the bearing preload bolt making it very hard to remove.

alfablue

nicklouse wrote:

alfablue wrote:

Park Tools web site says:

This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle.

The crank arm is actually secured in place with the two hex-nut pinch bolts on the side of the crank. Once these are secured I think the end cap could be removed, but I personally wouldn't bother.

YOU TRY IT. the crank arm claps onto the bearing preload bolt making it very hard to remove.

I will defer to your superior experience Nicklouse. My expectation was that this cap tensions the bearing until the crank is secured with the pinch bolts, after which the crank arm thus secured maintains bearingtension allowing the cap to be removed,much like one's aheadset top cap can be safely removed from the star fangled nut after stem bolts have been secured.

caw35slr

tompsk73 wrote:

hollwtech 2 deore

Herein lies the source of confusion. You can't have the above. You can have one of:

1. Deore Hollowtech:

Cranks held on with hex nuts that screw into the axle. See this exploded view of the latest M540 Deore Hollowtech crank:

http://techdocs.shimano.com/media/techd ... 608616.pdf

The crank/BB is an Octalink item. I think that the term "Hollowtech" refers to the crank arms, which are indeed hollow.

2. Hollowtech 2 (LX, XT):

These have a BB with external bearings. In the case of M580 LX, the drive-side crank has the axle attached. You push the axle through the BB, then you slip the non-drive crank onto it. You use a plastic twiddler to tighten a plastic pre-tensioner bolt (which pulls the whole thing together). Finally you pinch the non-drive crank arm onto the axle with a couple of hex bolts.

So Nicklouse was correct from the start, ride without your Deore Hollowtech crankbolts at your peril.

nicklouse

Caw dont forget that all the shimano cranksets have been available in HT1 format.

Alpha. yes you could run with out the end preload bolt just the tame as a top cap is not needed.

but if you a new preload bolt and fit it according to the instructions the crank arm does clamp down on it. Stopping it rotating and falling out (now i have heard of people losing them and that i cant explain).

alfablue

I suppose it depends if it is a Deore (Hollowtech I and Octalink BB) or Deore LX (current model is Hollowtech II).

caw35slr

alfablue wrote:

I suppose it depends if it is a Deore (Hollowtech I and Octalink BB) or Deore LX (current model is Hollowtech II).

Nicklouse is right. It depends whether it is Hollowtech 1 (entire Shimano range) or Hollowtech 2 (all bar Deore).

There is no such thing (yet) as Deore Hollowtech 2...all clear now? ;-)

supersonic

I think Deore will be releasing an external bearing crank, but not hollowtech ie hollow crank arms.