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I've decided to get a new chainset as my current 38T Nexus is giving low speeds with my Alfine 8 speed hub. I have my eye on the 45T Shimano Alfine chainset.

Currently I have a square taper bottom bracket installed, which has a 116mm axle length IIRC. The Alfine chainset looks like it has an integrated axle and includes a bottom bracket in the package. (To my surprise, given that I can get it for £45 - is that too cheap for a product such as this?)

If I purchase this product and this product only, will I be able to simply remove my current chainset (and bottom bracket), and stick the new thing in, hassle free?

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    That depends. Have you ever replaced a bottom bracket? – Daniel R Hicks Feb 23 '13 at 3:14
  • No but I know someone that has so it should be fine. – Fela Maslen Feb 23 '13 at 19:59
  • In terms of replacing a bottom bracket cartridge the critical factors are the width of the shell and the diameter and thread for the cups. Mostly (but not entirely) the cup diameter/thread is standard now, but there are several different common widths. Cups can be adjusted a little bit for a minor width mismatch, but it has to be close. (And, of course, all bets are off if you have some sort of exotic crank.) – Daniel R Hicks Feb 23 '13 at 21:38
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That really depends on your definition of "hassle free" and how much of a newbie you are. Personally, I always find square taper bottom brackets to be a pain the &*$#!

The square taper bottom bracket requires a special tool to remove it. The ever helpful Sheldon Brown has a list of the different types. the first or second one on the list is the one you want. It's a bit awkward to use, especially if your bottom bracket has had time to "seize" into the shell. You'll need a different tool for the integrated bottom bracket on the new tool, the Hollowtech II tool on that same list. It's much easier to use.

You'll also need a tool to remove your old crankset. The cotterless crank puller near the bottom of that same list should be the one you need. It's pretty easy to use, but be careful. There are two different sized heads and if you use the bigger one when you need the smaller one, you can strip the threads on your crank and then it's very difficult to remove.

Changing cranks and bottom brackets almost always effects your chainline. I can't find any measurements for either your current crank or your new crank. There are ways to measure and adjust for this though. Sheldon once again explains it all very well here: http://sheldonbrown.com/chainline.html.

It's also important to remember that one side of the bottom bracket has left-hand threads. I can never remember which one, but luckily it's usually labeled on the external (integrated) bottom brackets. If someone else knows off the top of their heads which one it is, feel free to edit it in.

Good luck!

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  • Thanks. I was mainly asking because I wasn't too sure that it would actually fit my bike without any extra components. – Fela Maslen Feb 23 '13 at 20:00
  • I've never had that much trouble with square taper. The only real problem is assuring that they're tight. – Daniel R Hicks Feb 23 '13 at 21:40
  • I hate all those cartridge bottom brackets; square taper, octalink, the works. The tool always slips off and I bang my knuckles against the frame. – jimchristie♦ Feb 23 '13 at 21:53
  • @FelaMaslen I forgot about chainline. I've edited it into the original answer. – jimchristie♦ Feb 23 '13 at 22:49
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    Re. the chainline - I would've thought that Shimano would make both "Alfine" hub and crank work properly together in that respect, although I should probably measure it for good, er, measure. – Fela Maslen Feb 24 '13 at 0:11

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