Apple's Weed Eater Bike

LewieBike

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May 21, 2014
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491
problems with all of these cheap weedy engines are the overhung cranks barely able to handle any side loading from a friction drive and they come with decent bearings.

They're aren't made in China, most are by Polo out of Mexico, and use US spec'd bearings. Even decent bearings aren't up to the damaging hammering that a side loaded friction drive on an overhung engine can create.

Cannonball2's Minimalist Friction drive using an older Echo 21 cc engine https://motorbicycling.com/threads/minimalist-fd.62572/
 


Will'smotobikes19

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Apr 9, 2018
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Most of them only have 1 bearing meaning there is only the back cover that bolts on instead of the other side of a crank I think that's another reason they fail. Some have the shaft on both sides but not sure which exactly maybe some Echos or shindawas. Chainsaw motors have 2 bearings. I don't know if the engine geometry of a chainsaw engine is better or what but I've heard they are more powerful than a weed eater engine. Perhaps longer stroke and some other factors make them a better option.
 
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LewieBike

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May 21, 2014
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491
I know on my Ryobi 845r, the older Ryobi 26 cc pushrod 4 stroke, there's two bearings with the cam gear in between them. It would be a half decent bike engine, a little anemic and possibly no faster than 24 mph.
 
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Jan 30, 2019
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I still don't understand what y'all see in friction drive. I bet y'all go through tires like crazy LOL
I have some fab skill, but I went friction drive for a few reasons.

The biggie was ability to do a rolling restart. Couldn't see a way to integrate that into chain drive. I wanted to be able to power to the bike trail, kill it, ride thru, and restart without stopping. I still need that crank time, riding is fun, but no engines for the parks and the yearly urban street rides.

The second was being able to remove it from one bike and put it on another. That one not as important anymore, it's where its gonna stay.

The third was simplicity, but I screwed the pooch on that one. But, I traded simplicity for a cool look and a bigger drive roller with swappable sprockets.

See the buzzbike thread.

I am doing a shifter chain-drive long wheelbase recumbent for my next one. That'll fill my stable with a fatbike, a recumbent, and another motorized pair.

Sit up or kick back, power or not, I'll have it covered.
 

The_Aleman

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May 2, 2007
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776
I still don't understand what y'all see in friction drive. I bet y'all go through tires like crazy LOL
FD is one of the simplest assist setups to install, and there's a nice variety of very reliable engines that bolt to it's mount. They can wear tires faster, sure, but if it's set up right, they don't wear the tire out much faster than any other motored bicycle. Friend of mine has over 3K on his FD's rear tire (CST1218). In contrast, my brother put Schwalbe Fat Franks on his Q-matic bike (leisurely, soft acceleration off the line) and the center was already nearly bald before 500 miles. Some tires simply wear faster than others, and dollars spent on a tire doesn't have much of an effect on that. The longest-wearing bicycle tire I have ever used costs less than $20, and that's the CST1218.

Also, FD setups, due to their drivetrain, send a light buzz through the bike. If you've never ridden a FD, the closest equivalent I can equate is to running a bottle genny off a tire. It sends a light "buzz" through the bike (not as pronounced as chinagirl, but smoother) and that sorta visceral feeling makes the rider feel more in tune with their bike. It's hard to explain unless you ride one.
 

LewieBike

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May 21, 2014
Messages
491
I run a v-belt pulley reduction from the weedeater to the driven shaft that spins the roller. Drive roller is a 3" diameter holesaw with welding 'spots' spattered on it. The tire I run is a Specialized 26' X 2.2" street tread, and it's still got it's chevrons on the center strip. Very little wear at all, if anything the roller will need some additional spattered welding to roughen up it's surface.


I don't feel or hear much from my drive. the engine makes a bit of noise, it's nearly 40 years old and has had a fairly hard use life. But it vibrates less than my CG engined bike. I think rack mounts tend to isolate the engine better than a frame mount.
 
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