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Brewer
09-24-2008, 08:25 AM
I'm having some problem's sourcing a rear suspension setup locally (New Zealand). However I've been looking at standard mountain bikes, and I was wondering if the bearings that hold the pedals would support the weight required?

Cheer's

n9viw
09-24-2008, 10:36 AM
I would more likely go with using a spare BB as a pivot point... weld it behind the original BB, and drill and pin a pair of non-drive-side cranks to the rear triangle. Alternately, you could weld arms from the BB spindle to the rear triangle, but that would obviate the ability to rebuild that BB.

You can often get bike shocks online, I think I saw a number of them available through scooter and kart stores as well, with up to 600# capacity on them. These aren't the air-oil damped shocks I'm thinking of, just the shock-looking things with external springs that you get on Wal-Mart bikes, they usually go anywhere between $10-25 USD.

Barring that, you might be able to find a 1" diameter compression spring at your local hardware store that you could pin between a pair of plates near the pivot point, to act as the rebound spring. You might also use an axle snubber (the rubber bumper on trucks that keeps the axle from hitting the frame at full suspension compression), bolt that to the bike and have a plate on the rear triangle ride on it - elastomer suspension!

TheKid
09-24-2008, 11:41 AM
If it's a bottom bracket that uses a 3 piece crank, you could insert 5/8" or 3/4" flange bearings for cart wheels, and use it as a pivot. Use a hardened 5/8" or 3/4" bolt between the bearings. You probably have to file down the threads in the BB to get the flanges to fit, as I did on my first tadpole project.

AtomicZombie
09-24-2008, 01:35 PM
Add two plates behind the BB, then get a tube to holt a pair of 1/2 inch ID brass bushings. Use a bolt and lock nut so the plates have no play, but not too much friction. You now have the same thing as a suspension frame.

http://www.lucidscience.com/temp/suspension.jpg

Brad

moejosteve
01-04-2009, 01:41 PM
I know this is an old post but I would like to revisit... I saw a pic somewhere of a shop-built rear pivot but can't seem to locate it. Any help?

I'm interested in building my own rear triangle and using a shock like this one http://www.bikebuyers.com/PART-SUS-R-MTB-750.htm (by the way, Bike Buyers has an e-bay store where their shocks are much cheaper).