Alt Bike Culture - Universal Joint on a tallbike?

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wethepeople
01-18-07, 05:17 PM
Is there any reason it couldnt be done?

I'm going to pick up a cheap U-joint and use it instead of lining up the forks because the head tubes are two different angles. I cant imagine why it wouldnt work, but then I'm not exactly the smartest person when it comes to these things.

Although I have already learned abit from building this.

Rincewind8
01-18-07, 06:17 PM
Just keep in mind, that a universal joint doesn't transmit rotation linear. Meaning the angle you turn one end is not the angle you get at the other end, except when it is straight. The larger the angle between the two axels the larger the discrpency. And at a certain angle it locks up.

http://en.wikipedia.org/wiki/Universal_joint
StokerPoker
01-18-07, 07:29 PM
Just keep in mind, that a universal joint doesn't transmit rotation linear. Meaning the angle you turn one end is not the angle you get at the other end, except when it is straight. The larger the angle between the two axels the larger the discrpency. And at a certain angle it locks up.

http://en.wikipedia.org/wiki/Universal_joint
would a CV (constant velocity) joint prevent these problems? It sounds like an expensive option. but I have a couple axel shafts sitting in a Geo Metro I'm parting out.

Rincewind8
01-18-07, 07:41 PM
would a CV (constant velocity) joint prevent these problems? It sounds like an expensive option. but I have a couple axel shafts sitting in a Geo Metro I'm parting out.
It would:
http://en.wikipedia.org/wiki/Constant-velocity_joint

But it's usually also a very heavy option. I would use the universal joint and keep the angle fairly low (<<45°).
frameteam2003
01-19-07, 08:07 AM
A fairly cheep and small(think bicycle) universal joint is to use a universal socket.They would need to be welded in place.
xlntRider79
01-19-07, 10:40 AM
You might run into a problem if the unversal joint isn't machined to very precise tolerances. Universal joints are designed for constant rotation in one direction. If there's any "slop" between the pieces, it will be hard to keep the wheel perfectly straight, and steering will feel a bit wobbly.
2manybikes
01-19-07, 06:42 PM
Is there any reason it couldnt be done?

I'm going to pick up a cheap U-joint and use it instead of lining up the forks because the head tubes are two different angles. I cant imagine why it wouldnt work, but then I'm not exactly the smartest person when it comes to these things.

Although I have already learned abit from building this.


A friend of mine did exactly what you are thinking about. It works fine, I have ridden the bike.
wethepeople
01-19-07, 08:24 PM
Well, no reason for it anymore. I got it to work, and here is some pics of the progress even though you guys have all seen tallbikes :p.

http://img.photobucket.com/albums/v419/wethepeople101/almostthere.jpg

And here is something else a friend made a while back, and yes, it does work.
http://img.photobucket.com/albums/v419/wethepeople101/kylesbike.jpg