The Urban Buzzbike (sprocket reduction friction-drive with 2 1/4" drive roller)



Joined
Jan 30, 2019
Messages
53
Just finished a 10-mile spin around the neighborhood. Rolling restart working good, pull-start after warmup takes one pull (for a weedeater motor, that ROCKS!!).

Stopped by store on the way home. Woman behind the counter tells me some older woman saw me go by the first time, shook her head, said 'I done seen it all now, someone put a weedeater on a bike...'.

Another bearded old man smiling, doing the twist-grip motion, I pulled in the clutch and revved it a few times and honked the horn as I went by the second time, made that smile bigger.

Seems older people see an old man on a motor bicycle, they smile.

I LIKE IT. Going back out.
 
Last edited:

KeepOnKeepnOn

New Member
Joined
Nov 28, 2007
Messages
16
It's hard to understand exactly how it is getting good pressure on the friction drive but that's real cool. It doesn't look like it would be hard to add a derailleur and multisprocket to make it a multispeed friction drive... and you obviously have the skills.
 
Joined
Jan 30, 2019
Messages
53
The triangles create a toggle-lockup at the tire contact point. I had two springs, removed one.

Also shortened the clutch lever arm (moved cable anchor in) to increase the travel. More wheel clearance, and depreasion. Now I feel the accel, mighty micro g-force that it is.

Moved a spring inline with the clurch spring, acting as damper to the engine platform.

Two more adds, a chain idler topside, and chain guard (more to keep oil slinging away from me).

Wore the first chain out (from last fall), stretched. Gonna keep an extra in the bag too. That chain got hammered with 'experimentation'.

I don't think deraillers work at this rpm. Adding idler to dampen oscillation at low rpm now, its like a resonance, repeating. I can't see keeping enough slop to jump gears, at that speed its more controlling tension to stay on sprocket without running too tight. The idler lets me loosen the chain tension while controlling slop on idle side, engine tips into the chain tensioners under load. We'll see how these little sealed roller bearings hold up.

Considered two idlers, 'cause rolling restart shifts the tension side, but its not causing an issue, so I skipped that.

Also took dims to make a second platform for the 26cc engine, got spares, and wanna have one ready to swap when I blow the innards outta this screamer.
 
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