FrictionFast Bike project

[Kepler]

Lever operated engagement is certainly a reasonable way of engaging the drive. Sounds like you will need to adjust your riding style to activate the drive but certainly doable. The RC motor whine is not my favourite noise so its good to here that your setup is less noisy. Definite advantage.

 

[rearengine]

Forrest .. Do you suppose it's the CAL-I- FORN-I- air ?? :lol: Seems like alot of good ideas come from the west... I think Australia is west of Wisconsin

I have an idea I want to throw in the mix.. What if we backed the front brake pads off some so we get more cable travel , and use a dual pull brake cable with one going to the rear for your engagement ? The left hand front brake lever stays where it is ... Half pull engage, full pull front brake ?? Bill

 

[McDesign]

Yes - could be done. What race cars typically do is have a "brake balance bar". The brake pedal presses the horizontal bar, which has a master cylinder for the front on one end, and another for the rear on the other end. As you vary the position of the pedal pressure around the center of the bar, it changes the front/rear brake bias. Many cars even do this during the race, to compensate for decreasing fuel load.

Street cars just have a shuttling piston to do this - easy with Juicy hydraulic brakes!

Have to think up a linkage - shouldn't be hard to make a pull yoke, 'cuz I agree one lever would be better.

Forrest

 

[rearengine]

http://www.choppersus.com/store/product/1161/RH-Dual-Brake-Lever-Blk-Slv/

maybe ??

 

[McDesign]

maybe ??

Thanks - yeah, I ordered one.

Forrest

 

[McDesign]

Lever operated engagement is certainly a reasonable way of engaging the drive.

Hey - first approximation - works fine! Drilled and tapped the steel chainstay for a casing stop; added a lower tab to the swing plate.





http://www.youtube.com/watch?v=Mqm7xfI8278

Rode around some; front brake only right now. I see the need for some cushioning in and out of engagement - whack-whack!

Forrest

 

[Kepler]

That is some serious clunk on engagment / disengment. Do you need it to swing that far? Seems like you are going over centre on the pivot. Maybe a spring on the stop wire and a foam block on the disengage stop will make it a bit smoother.

 

[adrian_sm]

Yeah. I would change the geometry to bite into the tyre quicker. Kepler's and mine both use very short pivot arms which keeps things compact, and doesn't allow the the drive to gain heaps of momentum, so no big clunk. Or moving the pivot point forward would do a similar thing, by allowing it to bite in quicker.

Anyway keep up the good work.

- Adrian

 

[McDesign]

Yes - it's clunk-y! But an experiment; and exaggerated by the bike just hanging from a 1x6.

Because of the way I set up the long swing arc for good roller grab, the swing plate has to move a long way. It does what I want, in that in the disengaged position, gravity holds it forward against the stop. In the drive position, gravity helps again, but by helping the plate swing backward.

I think I can design a 4-bar linkage that will give me the same "grab" without having the long swing.

Nice weather here's got me painting on the house this weekend, tho'.

Forrest

 

[spinningmagnets]

Clever solution! for those who want to make something similar without drilling into the stay-tube, here's one $11 option: http://www.bikebagshop.com/tubus-round-stay-clamp-set-p-1496.html

Using a hardware store "P"-clamp like this:

This also might work, a guide for brake/shifter cables, you could epoxy this close to cable end and hold it on with a zip-tie/hose-clamp...
http://www.niagaracycle.com/product_info.php?products_id=413104

 

[Hillhater]

I think I can design a 4-bar linkage that will give me the same "grab" without having the long swing.

you just need to reposition the pivot point closer to the motors.

 

[McDesign]

Yes, but then I wouldn't get the "leverage" I get now from the very shallow interface between the tire arc and the swing arc. If I take off that cable, the plate and roller will go around rearward until the tire is mashed flat against the rim - even with 50 psi in the tire. I can't believe it would ever slip - rain or not.

I want to maintain that if at all possible, 'cuz the roller was $30, and shows no sign of wear or cupping yet.

Forrest

 

[Hillhater]

.. but maybe you dont need ALL that leverage !..
..

 

[McDesign]

My (13 year-old) daughter's really been enjoying the bike - rides about every afternoon.

Lost it recently at a nice wide neighborhood intersection trying to maintain speed; swung wide and hit the only vertical object within reach - a concrete signpost, perfectly demonstrating the "stare into the crash" technique.



She was fine; was a steel fork, so I just straightened it.

I've made some changes to make engage/disengage softer and easier. It works well; I'll post some pix this weekend.

Forrest

 

[Hillhater]

you should have listened .. :lol:

I would recommend that you invest a little time & money in a brake up-grade before you experiment too much.
..Those calipers are going to work overtime holding back 2kw and all those batteries ! :wink:
.

 

[McDesign]

Yep!

It now has heavier cast calipers and mountain-bike pads from the parts bin; also the cool twin-cable-pull lever somebody here pointed me to, so it's got front AND rear brakes.

Got plenty of disc brakes; just need hubs with the thread.

Forrest

 

[amberwolf]

Maybe you should've put MikeFairbanks on her Foes list before she reads the forum, so she couldn't see his posts to imitate him. :lol:

 

[McDesign]

Just an update on the FrictionFast bike; it continues to plug along; maximum output from the batteries is generally 1050 Watts. I rode about 10-12 miles last night around our little town with no pedalling at all, just because it was a nice night and the kids hadn't ridden the batteries down. Still on SLAs; never experimented with NiCads.

Does about an Ah per mile at 36V with me on it not pedalling (210 lbs). With pedalling, kids can stretch the range to twenty miles.

Forrest

 

[McDesign]

Couple of pix, roller really wears in wet weather; 1050 Watts is typical peak.

View attachment 1



Forrest

 

[amberwolf]

That looks like the exact same Kenda Krossroads tire I used on my own friction drive, on DayGlo Avenger FD2.0.2. The drive roller I used was harder and slicker though, off a roller skate instead of a skateboard, so it lasted longer but it slipped more, especially when wet or dusty.

 

[McDesign]

That roller is 35 Durometer; I just ordered another one as well as a 80 Durometer version from McMaster-Carr to see how they compare.

Forrest

 

[KevXR]

I skimmed through this thread, some really good info.

Quick comments:
Steel non suspension forks are cheap. I replaced mine when I bent it. Fork failure is nasty.
Your two motor design reminds me of the ZAP friction drive.
Push-pull system, almost all off-road single cylinder motorcycles use push pull throttle cables. a souce for parts.

Has anyone created a "commuter booster" style system starting with a RC motor X mount?
http://www.leaderhobby.com/product.asp?ID=9394001226012
Outrunner - leave off one strut. Is there a way to mount an outrunner motor on both ends? Bearing mount.
Inrunner - mount a small roller on one strut. Use pullies or gears to reduce the roller speed. I have noticed most gas powered friction drives use a 1" to 1.25" roller. I want a light system for boosting on climbs only.

 

[McDesign]

Hey - anyone interested in this for free? It needs a 36V 40 A controller (old, used one caught on fire!), but else is fine. Projects have moved on, and I just hate to see this fun ride not being enjoyed.

Free for pickup to the first interested party, with extra AGM batteries and enough NiCad F-cells to power it twice again.

I'm about twenty miles east of Atlanta down I-20.

Forrest