Compatibility Question

[S6PNJ]

I have Ultegra 53/39 on my Trek 1500 at the moment and with the 12/25 on the back end, I need something easier for the hills for a sportive I have in about a month. I'm looking at buying a second hand Shimano R600 Compact Chanset 50/34, 170mm with BB Cups but am unsure if I can simply remove my existing chainset and replace it with this. Is there an easy way to check? The chap selling says all Shimano are compatible but mine has some sort of fixing in the middle:

whereas the one I'm looking to buy doesn't:


Is this going to work? I know I'll lose top end but I'm not worried about that.

[3216]

Yes it'll work once you remove the existing chainset and BB.

The reason that the new chainset doesn't have a bolt on the drive-side crank is that the axle is permanently fixed to it. You fit the BB cups to the frame, slide the axle through and push it into place, then fix the other crank to it.

[S6PNJ]

Thanks! I'm having a few issues getting my existing one off at the moment - I've managed to remove the 8mm allen key (bolt) and lock ring but can't see how the peddle arm and spider come free (correct terminology???). From the Shimano website, it looks as if it just fits on splines but despite a (little) bit of encouragement with a rubber mallet, it doesn't want to shift.

[Roman]

Much simpler to change your casette to a 13-27 or 13-29 to be honest.

[S6PNJ]

True! I'm also looking at fitting an 11/32 (MTB set) which I know will just clear my dérailleur once a simple mod has been applied (cable tie to hold the shift cable in a slightly different position and hence give clearance when on the 32T). I can get a 12/27 Ultegra that will fit straight on but it doesn't give me much extra over what I have already.

[B19GRR]

If you go with the compact you'll probably need a matching front mech too.

Have you got a long cage rear mech to take up the additional chain you'll need to run the mtb cassette, or does this simple mod you speak of sort that?

To get the chainset off the BB you might need a crank removal tool thing, dunno though as you mention splines, definitely need one on square taper BB:
http://www.parker-international.co.uk/6462/Pro-Cra...
Hmmm, bangs on about Octalink, tapered and ISIS BBs, so could bt the thing you need.

Cheers,
Rob

[3216]

B19GRR said:

If you go with the compact you'll probably need a matching front mech too.

A standard front mech will work fine.

[S6PNJ]

B19GRR said:

Have you got a long cage rear mech to take up the additional chain you'll need to run the mtb cassette, or does this simple mod you speak of sort that?

The mod simply pulls the cable upwards which in turn increases the distance from the mech to the gear thus giving more 'space'. It's a bit of trial and error but I know it works.

B19GRR said:

To get the chainset off the BB you might need a crank removal tool thing,
http://www.parker-international.co.uk/6462/Pro-Cra...

Judging by how hard it is held on, I'd guess that tool is just the thing I'd need - wonder if my old man had got one