Another Friction Drive, Last One I Swear!!

Hey, thanks C2 :)

Maybe I can play around with the location of the pivot point on my clutch to make it work. I can probably trim a half inch somehow. Either that, or I'm fabricating something, I guess. But a pre-made lever will look so much better.

Off to research!
 
I'm new and a complete novice and plan to build my first bike this Winter. I really want to use the DF Scissor Lift design and was wanting to know if there are any kits available. If not, I will try to have it fabricated. I have looked at kits and had seen one years ago and from what I recall they were constantly having to readjust the roller to keep enough pressure on the tire. I will be primarily using this bike off-road so I want to be able to adjust pressure on the go, since I am guessing this will be an issue.

If there aren't any kits available any additional design information would be greatly appreciated. Can't wait to get this going but I would really like to do it right.
 
The scissor lift is very simple, just two pieces of flat iron with a cable pull point in the center joint and a pivot point on the engine frame and the bike frame. Cable pulls the center point up goes the engine.
 
cb2;

Can you bump start the motor by dropping it on the wheel?

Does the spring have enough tension to turn over the motor?

About how fast would you have to pedal to, before dropping the clutch?
 
I have never tried to drop start one of the Lifans, I just use the recoil. I believe maybe Deacon drop started his. I will give it a try next time out. The Lifans have a great deal of initial compression, a good bit more than an HF engine. I have enough down force to kill the engine with the brakes even at a higher idle, so it follows it should start. Will let you know.
 
No dice yet on a drop start. I say yet because the bike has a new tire, the tires tend to be a little slick until you get a few miles on them, still might work.
 
great build, do you get a lot of vibrations. is the motor really secured... and could u possibly give me a detailed description on how you secured your wooden drive roller to the shaft?
 
Thanks DBM. The roller is retained with a bolt and large washer in the crank end. The washer is sized so it slips over the crank shaft. There is a piece of rubber about 1/4" thick on the engine side of the roller against a similar washer. When the bolt is tightened the roller is compressed into the rubber disc providing positive drive to the roller. This bike runs a 2.6" roller for speed. Tops around 40. Not as good of hill climber as some but reasonable on most hills.
 
Didnt answer all the question. The motor is basically vibless as are all my Lifan FDs. The engines are smooth, but I believe the tire absorbs any vibes there are while being driven. I get a small bit of vibes in the pedals at max RPM. The engine is very secure. Wouldnt be on there long if it werent. This one rides/pivots on a 1/2" bolt which is securely clamped/bolted to the frame. My Mongoose MTB with a similar drive is well over 2kmi with no issues with the installation.
 
Love the simplicity. Do you prefer the lifan over the predator for this style? I'd love to build one of these but the way Idaho defines a moped it can't have a manual clutch. already pushing it on the engine size.
 
Both are excellent engines and have their advantages. I have more Lifans and time on them than Predators. I think the Lifan may be overall a little more compact(minus the tank). I believe the Predy revs a bit higher and the Lifan makes a bit more torque due to a longer stroke. The only large engine I have used for direct FD has been the Lifan, but I dont know why a Predy wouldnt work as well. I have wondered if a lifting mechanism is a really a clutch, or simply a way to disengage the engine for pedaling? When in the drive mode the engine is a clutchless direct drive. Guess it depends on who you are trying to explain it to.
 
hmm good point. I re-read the statue and it says

"...the moped shall have a power drive system that functions directly or automatically without clutching or shifting by the operator after the drive system is engaged"
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To me, lowering the engine would be just engaging the the drive system. So thinking about this again, it would be OK.
 
Yeah, the lift seems to be acceptable under the law. While a hand lever is the preferable method of actuation it probably looks too much like a true clutch system. Maybe the lever method would be better from the legal stand point. BTW I have gotten the Lifan to drop start as was asked earlier in this thread. Much to my suprise! That would be a good argument for the lift as part of the starting system. Especially if the recoil was removed.
 
cannonball2 said:
Even Im begining to think I might be needing to check myself in some where for a little shock therapy. I realized I can ride an MB for 10 days and not ride the same one-sad! Oh well enough self examination. This is my latest bike, it came from the Police auction lot. Started as a Schwinn Ditch, I call it by a similar name. Any way it was in sad shape, the cool deep V wheels with the disc brake were trashed, so I pieced it together with what was on the other bikes. Had a NIB Lifan that Wayne Z nearly had me convinced to do an inframe with. Problem was I never liked the bike that was set up to do it on. Also I am big fan of big bore (100cc) 4 stroke direct drive bikes. The Lifans have proven to be perfect, or nearly so you do have to put gas in them. Any way this bike is very light and fairly fast for a 4stroke direct, 33mph on GPS with a 2.25" roller. Ran out of horse mat finally and used oak in the cheap and easy roller format. GREAT roller. I thought it might have to break-in. Bit like a bulldog from the get go. Has Deacons scissor lift clutch, works like a charm with very little effort. This bike is a sweet heart, very smooth, quiet, cruises nicely at 28mph, and is very simple to ride. Will probably replace my trusty Mongoose/Lifan that has about a zillion miles on it(sniff).
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Now that's what I want to see my idea is similar to yours, excluding the hinge, my idea will require a hinge to mount the motor a angle bracket etc. But I will be taking your idea for the lift so that's 3 ideas to make one good one.

Mine is clean cut your is diamond cut and the guy who started the door hinge idea was an ok idea. I was thinking cable lift. As for the gas tank how did you mount it on the engine? Isn't that dangerous?
 
cannonball2 said:
Both are excellent engines and have their advantages. I have more Lifans and time on them than Predators. I think the Lifan may be overall a little more compact(minus the tank). I believe the Predy revs a bit higher and the Lifan makes a bit more torque due to a longer stroke. The only large engine I have used for direct FD has been the Lifan, but I dont know why a Predy wouldnt work as well. I have wondered if a lifting mechanism is a really a clutch, or simply a way to disengage the engine for pedaling? When in the drive mode the engine is a clutchless direct drive. Guess it depends on who you are trying to explain it to.
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*Bing* I'll take roller for 200 alex, I need that I don't want some peg eating my tire away, I prefer rubber on rubber.
 
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