Tuesday, April 20, 2010

Incompatible

I have been planning to swap out the original crankset on my bike with a Sugino XD2 that I pulled off of a donor. The smaller chainrings on the XD2 will make it a bit easier for me to climb hills with a load. I was initially concerned about compatibility between the old bottom bracket spindle (taper etc.) and the new crankset, but after discussing it with friends I decided to give it a shot.

The original crankset secured with a nut.

Crankset removed. On the left is the Sugino XD2 with 46, 36, and 26 tooth chainrings. The old crankset is equipped with 50, 45, and 28 tooth chainrings.

After removing the old crankset I slid on the new one. It was immediately apparent that this wasn't going to work. This was as far as the crankset was going to go on the spindle.

I gently replaced the old one on the spindle for reference. I just noticed the rust on the dérailleur adjustment screws.

When I compared the two cranksets I realized that the backside of the XD2 crankarm protrudes and is flush with the small chain ring whereas the old crankset is recessed. I was hoping to save a little money by using the old bottom bracket. I'll just bite the bullet and pick up a new one tomorrow.

10 comments:

  1. Yes. Those smaller rings will be nice for camping...and climbing some of those steep gravel ones on the way to Muenster.

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  2. Rat trap:
    Not to worry. Your XD2 just takes a BB with less width (113-118) I'd be willing to bet your current BB is around 122 or so.

    You should just be able to switch to the compatible size to use the XD2.
    (I just found I had to do this myself when switching cranks....no big)

    usefull info on BB sizes/brands/and compatibility here:

    http://www.sheldonbrown.com/bbsize.html#sugino

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  3. Well, a BB cassette isn't too horrendous if you know what you're looking for, amd I think it'll be worth it for the extra low gears.

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  4. A dumb question here - might you just be able to swap chainwheels, allowing you to dispense with the need for even touching the bb?

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  5. Pondero-I had planned to do a worknight bike camping trip this past Tuesday but the heavy rain made me decide to wait till next week.

    I dropped down to my granny gear on a couple of those climbs. I'm not too proud to admit it.

    jtgyk-I think a 113 will do the trick. I should start checking Sheldon's info before starting anything.

    Steve A-Darn it Steve! Stop using common sense!

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  6. Just asking. It looked like both cranks had five arms and the same diameter chainwheel bolt pattern.

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  7. Steve A-They do look the same size but I couldn't help myself, I went ahead and picked up a new bottom bracket. At least the new set will have matching crank arms.

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  8. And now you won't have to touch that BB again. Unless you change your cranks. Again.

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  9. Doohickie, the eternal optimist!

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  10. and now you'll have another crank and BB to go onto another build....that you'll have some parts you want to switch out....and you'll have some extra parts to go on another build....extra parts...wash, rinse, repeat.
    OH! IT's sooo much fun on the cycle of cycles!

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