Shift On The Fly Friction Drive

[kerf]

Rained all day here so I put the day to good use. My wife's bike is a Staton friction drive with a TLE43. She likes to freewheel down hills like I do on the Snake-Eater, my chain drive makes it easy, just back off the throttle and you're freewheeling. Even with her clutch disengaged, sometimes it will reengage on a downhill run when you approach 40. I wanted to be able to raise and lower the drive roller from the seat and after a little thought decided to use a spring to load the roller. Actually, I used a storm door closer that provides 18 - 20 pounds of load on the roller.
A quick check of materials on hand and I fabricated an articulated strut to lift the roller, controlled by a lever located under the seat. Seems to work great but I need dry roads for a test. I'll pull it back down for painting after a full test.

 

[kerf]

Test complete! Man thats one sweet bike, lite and quite. Sometimes I miss that friction drive.

 

[fetor56]

Well executed man...unfortunately not the type of setup i can use cos i don't want my side struts to be able to move.
Doesn't that particular Staton drive roller come with a freewheel?
Anyway good job....if i concider changing setups at any stage i'll definately think about "liberating" your idea.

 

[kerf]

Centrifugal clutch but alas no freewheel. The spring loading has proved to be spot on, no slip, little drag.

 

[5-7HEAVEN]

Doesn't that particular Staton drive roller come with a freewheel?


No, but a 1.25:1 friction spindle and drive assembly from bikemotorparts.com could probably be retrofitted into the Staton housing. You would need to replace the clutch drum, spacer, bearings and roller.

Unfortunately that one-way spindle only comes in that one ratio size.

 

[kerf]

Thought about that but I've put an 1 3/8" roller in the bike so Mrs. kerf can keep up with me on the road. She does ok up to 35 or so, I still need to keep an eye on her in the mirror.

 

[fetor56]

Doesn't that particular Staton drive roller come with a freewheel?


No, but a 1.25:1 friction spindle and drive assembly from bikemotorparts.com could probably be retrofitted into the Staton housing. You would need to replace the clutch drum, spacer, bearings and roller.

Unfortunately that one-way spindle only comes in that one ratio size.

Be great if u has access to a warehouse full of miltiple vendors spare parts.....u could just sit there all day trying different things on different things,see if they fit.

 

[Happy Valley]

Pretty dang clever and innovative use of ready made components with the door closer, some great tinkering there.
Let us know how it holds up, if the need for any mods develop.
BTW, if you get a chance sometime, could you post another pic of the lever end of things? Not quite seeing how that actuates.

 

[kerf]

Followup Details

Camera batteries went belly up yesterday, so freshly charged I'll try again.

The challenge was the geometry of the linkage and keeping it away from brakes, feet and legs. Also having enough throw to properly operate the toggle.

My design calls for the toggle to over cam when disengaged, moving into contact with the clutch housing. By doing that, the spring tension holds the toggle in a locked position until thrown back by the lever / engaging rod. I cut material from the forward edge of the upper toggle link to allow sufficient over camming to give a positive lock.

The position of the engaging rod on the lower toggle link is critical. The best mechanical advantage would have the engaging rod connecting to the toggle at the pivot point. This had two issues, first the engaging rod contacted the underside of the clutch housing, second my lever would not have enough throw to operate it. By moving the connection point down on the lower link, both of these issues were corrected. The lever does not require unacceptable force to operate and shifting is very positive.

The lower spring mount requires a bracket that bolts to the upper dropout screw hole and rest on the lower frame tube. This allows the lower spring mount to clear the dérailleur. Lower spring mounting bolt is a 10/32 hardened Allen head screw.

 

[Happy Valley]

Yes! Amazing what new film in the camera will do. ;-)
Great pics and explanation there. I'm left wondering how you did that underneath shot but it really shows the whole thing well.
Very clever Kerf, I think you oughta be talking with Dave about royalties.