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Old 01-12-08, 04:31 PM
Cyclaholic's Avatar
Join Date: May 2005
Location: Sydney, Australia
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Bikes: several

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Originally Posted by roughrider504 View Post
Cyclaholic, are you going to raise the second rear triangle any? If you don't the frame geometry will be off and you'll probably need shorter cranks. I have the same sized wheels and I had to raise mine to get the top tube back level. I don't think the 24'' rear wheel is a good idea since its normally a good idea to get as much BB height as you safely can for these extended bikes. Whenever I had the bike mocked up, I used 26'' wheels [frame meant for 27''] with 170mm cranks [165mm now], and that was enough to give me some problems with striking.

EDIT: One solution to your seatstay problem could be somehow using an axle that goes through your bottom bracket to mount the second rear triangle. You can probably find some large washers that fits right in the cups or something like that.
Yeah, I don't want to lose any bb clearance and I've been thinking about just how to best address the geometry question. I also confirmed my suspicion that the stays on the main frame interfere with the chainline and it's worse than I first thought, so they have to go.

The upside is that by replacing the seatstays and chainstays of the main frame with tubing I'm free to position the extra triangle wherever I please. I'm free to arrange the frame geometry to accomodate the 24" rear wheel and give the bb as much clearance as it needs. It just means a bit more work than first anticipated.

Originally Posted by badmother View Post
Cyclaholic- what about using a 26" wheel and some "road brakes" if that can be found? You can buy some special brakes that can be used for two diff sizes of wheels, but hallf the fun is to make it low cost.. Maybe make some sort of extension to the brake arms? Then ofcourse there is the hub breake posibility.

I am lucky, there is a unlimited access to dumpster bikes in the area. I pull them out and give them to the refugees in the area, and I find all I need for my projects. Also wheelchairvheels for trailers.

Do you think your rear triangel would be stronger if you put a seattube innside again? Maybe the top of that seat tube could help you find a way to connect to the main frame, especially if you need to go "weld free".
I'm fortunate that welding is not a problem. However, I'm a bit more limited in my choice of dumpster bikes and a good find here is a rare find so I want to use what I have at hand. Unfortunately I don't have a spare 26" rear wheel, only that 24" which is in perfet conition. like you said, half the fun is keeping it low cost.

I like your idea of extending the brake arms, I hadn't thought of that! It's the rear rear brake so I'd be willing to give it a try. They're V-brakes made of pressed steel so cutting and welding in an extension on the arms shouldn't be too difficult. I'll put this one away in the memory bank i/when the opportunity arises to onvert it over to a 26" rear wheel.
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