Compact Crank Compatible with BB-5500
 

I am looking for a low cost compact crank to replace a Shimano 105 Hollowtech with a BB-5500 bottom bracket (68 - BC1.37x24 - 109.5). Will an ISIS compatible crank fit? My existing BB could probably due with replacing. Am I better off up upgrading the bottom bracket? There don't appear to be a lot of compact cranks that are compatible with the BB-5500. Thanks!

Octalink and ISIS is not compatible the Octalink is proprietary to Shimano you have to stick with a Shimano Octalink crank *

or take the BB out and get some other combination of Crank+BB..

* Though some others licensed to use the the BB design.. they quit when Shimano dropped it, themselves..

It is often easier and more economical to buy a crankset plus suitable BB (they are often bundled at a favorable price) than trying to find a crankset which suits your requirements and also fits/works with the existing BB

So if I change my BB, the I can pretty much buy any crank/BB combination that will fit my 68mm English thread, keeping in mind that my current setup takes a 109.5-ish spindle? I really only need the compact for one particular 50 mile ride that has a 4.7 mile section of average 9% grade. I have already put on an 11-28 cog with my standard crank but I am hoping that a compact will make that climb slightly less miserable! The descent is pretty fun if not a bit scary! Thanks!

If you're willing to swap out your bottom bracket, just select whichever BB is compatible with the crankset you choose. As mentioned above, you can find cranksets bundled with the appropriate bottom bracket.

As for spindle length, that's generally determined by the geometry of the crank arms. Your current cranks may require a 109.5 mm spindle, but it's quite possible that a different crankset would be designed for a different spindle length.

Why a BB-5500? Do you already have it?

Because any Hollowtech crankset will work fine with your current bottom bracket. And Hollowtech bottom brackets are cheaper than Octalink ones.

Yeah! I already have a BB-5500 which I am sure still has plenty of life in it but it has been in the bike for almost 14 years so I am happy to replace it.

Thanks for input! I found a good deal on an Ultegra 6750 compact with a 6700 BB.