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M o n a x,
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Tony Adams
email: tony at atoms.net

web: atoms.net

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Bottom Bracket, Cranks upgrade

Thanks to a lot of helpful peeps at Blue City Cycles, BikeForums.net and The Chainlink, I finally upgraded the Schwinn's bottom bracket, cranks and pedals. As you may be aware, these old Schwinns have a larger unthreaded bottom bracket, so tossing in a replacement cartridge is not an option. There is a beautiful adapter though, made by Truvative, which converts the big old American BB to a nice standard Euro version. It was supposed to be a straightforward operation, but my particular early 1980's Schwinn has an obstruction - an inner sleeve which gets in the way of the screws that hold the two sides of the adapter together. After a lot of consulting on bikeforums.net and the Chainlink, I decided to file a path for the two obstructed screws. Yes, it took hours of filing, but it was worth it. Or at least I keep telling my stubborn and frugal self that it was worth it.

Here are the two channels I filed:

Here I test the two screws to make sure they clear all obstacles before pounding in the non-drive side adapter: They threaded in clean with plenty of clearance in case I didn't get the second adapter exactly lined up.

Here are both sides of the adapter installed:

And here is the Shimano UN54 installed:

add some (used Sugino $20 at LBS) cranks:

and some parts bin pedals:

and viola, a couple solid days of work and my twenty minute upgrade is done:

I think the bike lost at least a couple of pounds. It feels much tighter and smoother, but it was due for an overhaul anyway, so it is impossible to say for sure how much of that improvement is due to the upgrade itself.

tags: bike, DIY

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