Originally Posted by Darth_Firebolt (Post 11699230)

is one single speed and one fixed?
i remember reading about a dual drive track bike sometime ago. the singlespeed side had a bigger cog to accelerate faster, and the locknut on the fixed side was spaced so that a few revolutions of the wheel would spin the fixed cog into the lockring.

Originally Posted by ppc (Post 11572084)

I just came across this page that deals with the bizarre idea of running two chains on a bike, when I read the following nugget at the end of the page:

However it got me thinking about another bike I'd seen with a similar set-up but this one made a lot of sense. In 1982 Canadian rider Jocelyn Lovell rode the kilometre time trial at the World Championships in Leicester, England using a bike with two transmissions. His arrangement gave him two gear ratios, a lower gear to get away from the line and a higher gear that kicked in after about seventy metres. His ride in Leicester wasn't as good as he hoped for but the transmission worked well and it could not be faulted by the UCI commisaires.

http://2.bp.blogspot.com/_ERxywogDj9.../Jocelyn1b.jpg

Jocelyn's bike had a freewheel sprocket on the normal right hand side and a fixed sprocket on the left hand side. As he moved away from the line he drove through the RH sprocket and the left hand fixed sprocket began to unscrew from the hub. It being of smaller diameter it turned at a slower rate than the RH sprocket and being on the "wrong side" of the hub it would naturally unscrew. After about seventy metres the LH fixed sprocket came up against the lockring and at that point drive was through the LH side and the RH sprocket freewheeled. The distance traveled before the higher gear engaged could be adjusted by setting the position of the lockring. The bigger the space between lockring and sprocket at the start the longer the distance before the higher gear engaged.
Jocelyn experimented for some considerable time to come up with a combination of sprockets and chainrings that would not only give two suitable ratios but that would need chain lengths that would be at the correct tension. He settled on a low gear of 42x13 (87.2") and a high gear of 53x15 (95.4")

Wow, that is incredibly clever and a very elegant working around (or within?) the UCI rules. Lovell was a genius. I'm almost tempted to try it myself to see what it feels like :)

(There's just a small misunderstanding of how the system worked in the above explanation: the LH sprocket unscrews because it is smaller and thus spins *faster* than the wheel in the first 70m, not slower)

Originally Posted by Darth_Firebolt (Post 11699230)

is one single speed and one fixed?
i remember reading about a dual drive track bike sometime ago. the singlespeed side had a bigger cog to accelerate faster, and the locknut on the fixed side was spaced so that a few revolutions of the wheel would spin the fixed cog into the lockring.

Originally Posted by Poster on CL

dual drive...this makes the frame so stiff and responsive its amazing!

Originally Posted by WoundedKnee (Post 11699302)

I was thinking about this awhile ago, what if you did that with two freewheels? Would you be able to ride forward, backward, AND coast? My head asplode

Originally Posted by dsh (Post 11699308)

No, it would be the same as a fixed gear.

Grab your geared bike and roll it backwards.
Watch the cranks.
That would happen.

Originally Posted by Lilcphoto (Post 11699398)

Hey drive side photo FTW!

Originally Posted by Scrodzilla (Post 11702718)

Dude should mount both crank arms pointing in the same direction. Kangaroo bike FTW.