Alt Bike Culture - tall bike won't handle properly

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teddyki
03-03-12, 06:24 PM
Hey all!
I've been working on this tall bike for the last few days and I don't seem to have the handling down right. When it's clamped under this set up turning the bars on the top bike will force its bottom bracket off the post. I'm sure if I welded it like this then it would either be really hard to turn to the point of probably breaking my welds. What am I doing wrong / how can I get it to work?? Any help is greatly appreciated, this is my first tall and not sure exactly how the pivot points work.

239891

unterhausen
03-04-12, 09:42 AM
you need to make the steerers line up, or else use a chain to link the two.
teddyki
03-04-12, 09:53 AM
you need to make the steerers line up, or else use a chain to link the two.

So you're saying I need to make the headtubes the same angle AND lined up directly, I'll try that now. I'm not sure what you mean by using a chain.

unterhausen
03-04-12, 10:14 AM
Yes, same angle and lined up. All the pictures I have seen of tall bikes ditch the top fork and extend the lower steerer up to the top steerer.
teddyki
03-04-12, 10:30 AM
Any ideas on how I would do that with a bottom bike that has a threadless headset? Right now I was going to weld the fork dropouts to the sides of the stem, which is luckily steel, but that makes it not perfectly direct anymore.
unterhausen
03-04-12, 12:47 PM
weld a tube to the part of the stem that clamps to the steerer of the lower bike.
frameteam2003
03-11-12, 04:34 PM
I agree,flip the fork around in the correct possion and put a short section of handelbar in the lower sten and well bolts out the ends to attach the top fork.
The Speaker Guy
03-12-12, 01:49 PM
Or a drive shaft with a U joint on each end will take up a bit of misalingment
Dave Armstrong
03-12-12, 06:09 PM
241116


It might be the curved part of the forks on the top frame are throwing off the alignment.
unterhausen
03-12-12, 06:46 PM
you could look at it that way, the trick is to put the fork dropouts at the same distance from the center of both steerers. It seems that most people just cut the fork up and replace the blades with a piece of tubing/pipe so it's easy to tell if it's lined up and at the right angle
klunkrleaguenow
03-22-12, 03:14 PM
i made a jig for mine, a piece of steel pip perpendicular to the floor, strip both frames and slide them on the pipe by the head tube. Then you can clamp them in position with the BB of the top frame seated against the seatpost of the bottom frame. Once the head tubes are aligned then weld the two together at the BB union. Then you can weld in your steer tube, you have to make sure its strong and aligned properly because the steer tube is now supporting the entire weight of the front end.