Twinned friction drives?

[peterjd_uk]

Having finally got my (robust) Raleigh large wheeled (700c) bike (pedelec converted with a Swytch hub kit) to an acceptable weight distriubution and hence more pleasant to ride over extended trips, my attention has turned back to my (odd!) Bickerton folder. I have had the latter working with a cheap friction drive on the back wheel with some success. However I have two identical cheap motor drives which with the controller I am using can be driven in either direction. The question in my mind before I see how I might rig both up to drive the back wheel with the tyre sandwiched between is synchronising the rotation of both drives? Are there any electronic people out there who may be able to suggest how that could be achieved? I am pretty sure there is a speed signal(?) from the controller but the motors themselves only have the 3 phase inputs. Thanks Peter

 

[vfr400]

If they're 3-phase, you need two controllers.

 

[peterjd_uk]

If they're 3-phase, you need two controllers.

Yes I am planning to use two of the controllers but is there a problem of the 'pinch' wheels on each drive trying to rotate the bike wheel at slightly different speeds. They I would think need to be synchronised to drive at the same rate. I suspect this might be more difficult to achieve [UL]automatically[/UL]?

 

[vfr400]

Yes I am planning to use two of the controllers but is there a problem of the 'pinch' wheels on each drive trying to rotate the bike wheel at slightly different speeds. They I would think need to be synchronised to drive at the same rate. I suspect this might be more difficult to achieve [UL]automatically[/UL]?

No, the motors will find their own speed.

 

[Zebb]

May I ask what friction drives you have.? Just out of curiosity. thank you.

 

[peterjd]

May I ask what friction drives you have.? Just out of curiosity. thank you.

They both came from Banggood - surplus items (without controllers) at about £80 for the first one and ~£65 for the second (which came from the Polish outlet). Look for "200W 24V Bicycle Bike Booster" - I have done everything with a 36V supply and similarly spec'd controllers not 24V. Peter

 

[Zebb]

Thanks for the information, it's appreciated.

 

[vfr400]

They both came from Banggood - surplus items (without controllers) at about £80 for the first one and ~£65 for the second (which came from the Polish outlet). Look for "200W 24V Bicycle Bike Booster" - I have done everything with a 36V supply and similarly spec'd controllers not 24V. Peter

Do they run at full speed with ebike controllers? I would have thought that the commutation speed might be too high.

 

[peterjd]

Do they run at full speed with ebike controllers? I would have thought that the commutation speed might be too high.

I've only trialed it once on the Bickerton using a bare board controller also from Banggood. At a medium speed setting without PAS and using the mechanical engage lever supplied. It powered the bike at fairly slow speed and the motor didn't seem stressed. Peter

PS I've decided not to try to run two electric drives on the Bickerton. As a bike the Bickerton is already sufficiently unstable without electrics. So having transferred my rear pannier rack from my touring bike (since sadly no longer touring) I going to work on a more stable fitting for one of the friction drive units at the rear, with battery in a pannier, and add a removeable aluminium tube between the handlebar and the main beam (ie similar to the geometry of a normal hybrid). Still won't be a legal pedelec but could use it legally on cycle paths. P.