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Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

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Old 04-16-05, 10:08 AM   #1
bike-ninja
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New BB for Raleigh Twenty ?

Hi everyone - I want to replace the bottom bracket on my Raleigh Twenty. I'm interested in going the Shimano UN72 with Phil Wood retaining rings route. I know lots of other folks have done this before and I was wondering if someone knew the proper bb size. Currently Nashbar has this bb in sizes 70x115, 70x113, 70x107 - but the bb is also available in sizes 68x107 and 68x113.

Thanks for any advice!
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Old 04-16-05, 04:22 PM   #2
cheg
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I think you need a 73x113 or 73x115. The bottom bracket shell is unusually wide in the 20 so you need a longer bearing to be sure the rings will clamp down before you run out of threads. The axle length you need depends on what kind of gearing you use but a long axle (at least 110) should work.

BTW: don't let them sell you a UN73 instead of a UN72. Many places consider them interchangable but that's not true for the Twenty because one end of the bearing is threaded on the UN73.
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Old 04-19-05, 08:13 AM   #3
LittlePixel
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when you get it you'll need to remove the black alloy collars from the cartridge - some people have had no trouble doing this by simply putting the thing in a vice and knocking out the cartridge with a wooden or rubber mallet (or a real hammer with some carpet or similar deadening material between the contact areas.

In my case though - the collars were glued on with this white gak and in the end I had to saw one (carefully) off with a junior hacksaw. It took two cuts on opposite sides and some persuasion with a stone chisel to finally get it off. But it was worth it. I think the oft used phrase is 'buttery smooth'

Keep us up to date with your twenty developments....
My Twenty:
http://212.67.202.78/~littlepixel/twenty/index.htm
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