HF 2.5 Friction Drive- A Different Approach

The roller diameter is the ONLY determining factor, not tire size. Took me by suprise when I started the FD thing.
 
Understood, but I will be using a jackshaft for the roller so I can target a given ratio by changing the pulley size of the roller shaft. Sounds like there is no disadvantage with a larger roller so I think I'll go towards the direction of 4" roller, a 2.25" pulley on the roller shaft, and the 3.2" maxtorque clutch. This should yield a theoretical 40MPH @ 4800 RPM, 30 MPH @ 3600 RPM, and 21.8 MPH at 2600 RPM which seems like a nice cruising range of 20-30MPH.
 
With those pulley sizes you are overdriven by a factor of 1.4@ 4800 rpm the roller will be turning 6826 that would be a healthy top speed around 81mph.
 
Ahh you are correct, mixed up a formula in the spreadsheet (doing ratio division backwards)

so scratch that, instead would target a 3.2" pulley clutch, 4"-ish driven pulley, 4" roller. This would yield theoretical speeds of 45.7 MPH @ 4800, 34.3 MPH @ 3600 RPM, 24.8 @ 2600 RPM, 14.3 @ 2000 RPM (clutch engagement). So sounds like with a 4" roller, a 4" pulley or slightly larger will put me in a good starting range.
 
Might work with no hills. Will not be a good "traffic" bike, but if you live in the sticks like I do then it could be ok. Awfully tall ratio for 3.5hp.
 
OK good to know. Well now that I am doing the math right at least I can order the right parts :)

I hear these engines like to chug along at the lower RPMS, is your typical "comfortable cruising" RPM say 2500-3000?
 
I only have one HF engine and it doesnt mind reving. The Lifans run over 4000 at cruise and you would never guess it. In short dont be afraid to let it rev. They are smoother over 3400 any way. My preference is to turn a smaller roller faster. It will be interesting to see what you get with the 4" for perfromance. Thats the beauty of this type roller, its so easy to just make another. Allow some adjustment in your design to accomadate a large dimension change if necessary.
 
On my 99cc friction drive, I have a 3" drive pulley to a 4" jackshaft pulley with a 3.5" roller, and it tops at about 40mph and 4500rpm.

The engine happily cruises as slow as 2500 and doesn't mind sustaining 4200 for as long as the gas lasts .
 
Somehow I missed this thread when it was current news, but the information here is valuable anytime. CB2 gave me this link when I asked him about combining a rack mount 3 hsp four stroke with his current experiments using an old 3 speed Sturmey Archer internally geared hub as a friction drive, a recent development in his Maytag Mayhem thread...
http://motorbicycling.com/showthread.php?t=57197&page=24

So far so good. About a year from now the 99cc predator engine currently in use on my daily rider, a 1950 Panther, is being replaced with a vintage 147CC Jacobsen 2 stroke and the Predator engine will be free to power something else. The something else I have in mind is pictured below, something I found at the local dump. It occurred to me in staring at it that it would make a nice friction drive with the Predator rack mounted and if possible utilizing the S.A. IGH as the roller. Not only does it make three speeds available at the touch of the shifter lever, but the spoke drive system makes slippage in wet conditions a non issue. So I'm exploring the idea and closely following progress reports on the current Maytag build. Not meaning to highjack this thread, but being an old one perhaps it is alright to add to it a bit. Hats off to CB2 for his many contributions to this forum!
SB
 

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Thats the same thing basically. Im not familiar with the 2speed hub but the operation is the same. The only problem with the IGH hubs is that they tend to make a roller that is too big for lower HP engines with out some form of reduction. The motor like he is using commonly turns a 1-1.25" roller. Where as the drive will work in the lower gears, the engine is overloaded in the higher ranges. He may have some reduction in the chain drive I couldn't se it very well.

Still it s great to see more of these builds happening. Thanks for the link.
 
mat_man said:
This guy may have something close to your idea:

Project 2-speed friction drive bike start up
https://www.youtube.com/watch?v=C3gQHNGewJU

His build was documented on the other forum.
Click to expand...
Thanks, m_m
Hard to tell much from the video, but that the hub is Shimano and chain driven. Couldn't find the build thread. I wonder how long the hub lasted. I'm guessing it died like the Shimano CB2 tried. I also wonder if reversing the engine would have resulted in 3 speeds rather than 2.
SB
 
Actually the hub is turning in the normal direction on that side when used as an FD, so it must be a dedicated 2speed. It does look similar to a Shimano.
 
He took (or burned) one of the speeds out, to use as a neutral.
I think that he should have used a Deacon/CB2 scissor lift and kept the
3 speeds.

The Shimano hub is cheaper, easier to find. I can find complete
bikes for 15-25 dollars on CL. It is oiled thru the shifter chain.
the SA is oiled thru a cup that may be in the way.

Lubrication would be the problem. Hi temps and speeds might tend
to sling it out. Multi-viscosity differential oil might be the key.
I am thinking 1 drop per 100 miles.

I will PM the build link.
 
Thank you, m_m. I'll be interested to read it. I don't think it is a secret here that there is another forum, but a pm is fine, too.
SB
 
There are so many interesting builds on this forum but this one really captured my attention. Thank you for sharing all of your amazing projects Cannonball.
Hugh
 
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