In frame Predator fricton drive build

That spring loaded "constant tension " pulley is very interesting . Has anyone used one , maybe even for other purposes . If it works as stated on the website that could be the ticket .
 
Yeah, I've been lookin at those real close. Thinkin seriously about tryin on of the $80 ones on my new build instead of tryin for 2 speeds. The cost difference for dual pullies, belts, and idlers is neglible, along with the simplicity of a single adjustable on the fly idler, makes one look better every time I think about it.
 
I guess you would have to use it as the drive pulley instead of the driven pulley ? Would you have to lower belt tension to run faster top speeds ?
 
From my calculations, it would be geared way too high if used on the motor unless you used a large driven pully or sprocket nearly the same size as the wheel.

It will work used on the jackshaft, with a 2" motor pully and a 10 tooth sprocket on the jackshaft driving about a 72 tooth on the wheel. It also wouldn't be possible to use an idler clutch with it mounted on the motor, it would start out in high gear.

It would work out well for a jackshaft FD though, then you can use a cent clutch with 3" pully on the motor for less slipping and less resiatance than a 2" driver would have.
Then you would increase idler tension for a higher gear, and could opt for an idler clutch instead of a cent clutch.
 
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I'm sure the answer is going to be yes, but has anyone tried a friction roller from Mcmaster-Carr for a FD bike ?

McMaster-Carr

The Sure-Grip tear drop shaped one looks interesting.....you could increase the pressure on it from a stop for good grip and a lower ratio, then back off for light loads/cruising.

MHF
 
motorhedfred said:
I'm sure the answer is going to be yes, but has anyone tried a friction roller from Mcmaster-Carr for a FD bike ?

McMaster-Carr

The Sure-Grip tear drop shaped one looks interesting.....you could increase the pressure on it from a stop for good grip and a lower ratio, then back off for light loads/cruising.

MHF
Click to expand...

Interesting roller, but will it get smaller? I can see it changing loading. Seems if you were to put a lot of load on it it would flatten offering more surface to the tire. Is that bigger or smaller or the same? The perimeter rubber "ring" above the tear drops has to go some where(in a linear fashion I imagine) so it appears it would oval or something similar. Might not change ratio much but would offer some great grip! Maybe good in the rain. This one is hard for me to figure. What do yall think?
 
Hmmm, I don't think the ratio will change when compressed. The perimeter size doesn't realy change when compressed and one rwv still covers the same distance.
Might be good traction though for the reasond CB posted.
 
From my experience with drag racing on wrinkle wall slicks, as the wheel twists inside the tire and the sidewall wrinkles up, the axle centerline gets closer to the ground. The driveline "sees" this as a smaller diameter or shorter tire.

I'm not sure if the tear drop roller would deform like that under pressure, but if it did, it would definately act like a smaller diameter drive roller.

MHF
 

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motorhedfred said:
From my experience with drag racing on wrinkle wall slicks, as the wheel twists inside the tire and the sidewall wrinkles up, the axle centerline gets closer to the ground. The driveline "sees" this as a smaller diameter or shorter tire.

I'm not sure if the tear drop roller would deform like that under pressure, but if it did, it would definately act like a smaller diameter drive roller.

MHF
Click to expand...

I think it would act as a smaller roller as u say because the axle is closer to the work
 
I can understand how the wrinkle slicks would let the driveline "see" a smaller tire dia. when they are slipping and burnung out.
But as soon as they grab traction that effect prolly dissapears. If the perimeter of the tire or wheel is say 40" or 4" or whatever, the distance that the tire or wheel covers in one revolution will be the same no matter where the axle is in the wheel if it's not slipping.
 
Wouldn't the flexable roller act like a lever (or gearing )and give more torque kind of like the hop along bike where the weight of the rider applies more pressure on the taller part of the wheel on the down stroke as he hops along on the platform? the torque in this case would seem to act in reverse allowing the motor hp to turn the roller faster through the short stroke side if the roller
 
Those Sure-Grip drive rollers are indeed interesting, Fred... $30 - $60 for the different options... which would you try first? :-)

...and what width contact patch would be advisable? They seem to come in 1" width and 2" width.

Seems to me that a hinged rear shaft that moved maybe 1/4" or 3/8" would not affect belt tension too awful much. It would give max belt tension AND roller friction, (with minimum diameter), from a start, with the shaft eased forward creating a higher ration, and less belt tension when the torque was not needed so much... I think it might work!
but my litebulb is kinda dim anymore :-)
rc
 
Save yer money. The wheel, compressed or not, still will travel the same distance on it's perimeter for each 1 revoluton That means the tire it's driving moves the same distance too.

A 3" wheel for instance, has a circumference of 9.42". Imagine this wheel, and it's axle, with a paintmark on it, rolling on a flat plane.
If the axle is compressed , the wheel still has the same perimeter distance, and will still cover 9.42" each time the paint mark hits the plane. No change in ratio, but prolly less torque, from unnessary roller pressure causing more resistance drag.

Think of the wheel's surface speed. It will be the same compressed or not.

Prolly still make a great roller though, I would go with the 2" diameter for the most contact.
 
tnx Wayne.

Hmmmm.
makes sense.... diameter may change, but the circumference does not. it's linear length remains the same.

ok...

So a drive cone, shoved at the top of the tire, from the side, WOULD change the ratio???
:-)
heck i dunno...
just thinkin.
(it hurts!)
lol

i spose the cvt sheave is abt the best way to go on these without getting too fancy, when ur looking for automatic drive ratios.
rc
 
Seems like a cone would cause wear. As the dia on one side of tire would be more than on the other, causing a twist effect on the contact area.
 
I built a rack mount with a vert. Briggs with two 45 deg. cones, One on the crankshaft to drive, and one opposite as an idler to keep the wheel from flexing away from the drive roller.

Worked good, but the tire wore down to the cords in about 25 miles.
 
I saw a mower bike before on Youtube, that used a cylindrical idler on the left side and the motor spindle with a 3" aluminum cylinder on the right, and they said it lasted a pretty good while with cheap tires. What kind of tire did you use?
 
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