Lifan Rear Rack Mount (new rack-no weld)

lowracer · Jan 3, 2011

I am settling on rear rack & leaving this bike alone (I promise this time...lol)
This engine has been on the front, then rear, then front again, then pusher trailer, now back on the rear.
I built this new rack using longer 'L' angle iron & firmly connecting the front to a cutoff handlebar & using a 3/8" threaded rod to go thru the handlebar & bottom section of both angle irons. I used 5/16" bolts w/ nylock nuts for the rest of the connections. Its V-Belt driven & does 50+ mph.
Having experimented with different layouts & racks, this version is the best place for this frame & this engine having the least amount of powerside interference.
Hope you enjoy the pics
-lowracer-

corgi1 · Jan 3, 2011

looks great,are the down stays from the motor rack mounted on the axles?

lowracer · Jan 3, 2011

corgi1,
Yes, the down stays are mounted to the rear axle. I slotted the bottom so that if the need should arise to remove the rear rack, the front mount & axle nuts can be loosened & the rack lifted off (to change a flat tire, etc.)
I plan on making an additional brace on the v-pulley side using the rear disc mount tabs & the hole in the down stay to bolt everything together & further prevent unwanted loosening under stress. I can also use the rear section of the fork end dropout to mount another 3/8" bolt behind the axle bolt...
-lowracer-

5-7HEAVEN · Jan 3, 2011

lowracer said:
I am settling on rear rack & leaving this bike alone (I promise this time...lol)
This engine has been on the front, then rear, then front again, then pusher trailer, now back on the rear.
I built this new rack using longer 'L' angle iron & firmly connecting the front to a cutoff handlebar & using a 3/8" threaded rod to go thru the handlebar & bottom section of both angle irons. I used 5/16" bolts w/ nylock nuts for the rest of the connections. Its V-Belt driven & does 50+ mph.
Having experimented with different layouts & racks, this version is the best place for this frame & this engine having the least amount of powerside interference.
Hope you enjoy the pics
-lowracer-

Props to you, lowracer!

Man, that engine sits so high your bike looks like a "slingshot dragster", lol.

Good job, though, very clean. dance1

lowracer · Jan 4, 2011

5-7,
Thanks.
I kinda wish the carb on the Lifan could suck gas up. Then I'd be able to remove the very high gas tank & move it lower & off to the side.
Any idea without replacing the carb?
I'm a firm believer in the K.I.S.S method of MB building...
-lowracer-

msrfan · Jan 4, 2011

You can buy an impulse fuel pump and put it in line from a lower tank to the carb. Just have to install a hose nipple in the crankcase for the impulse hose. Briggs and Kohler are two brands that use these on some of their larger motors.

pinjas · Jan 4, 2011

I don't know if it's the little fuel tank on top, but that engine looks pretty big. Pretty neat work on the rear mount, how is it you decided to stick with the rear mount? All that back and forth, I'd like to hear more detail about your decision making process or your experimentation.

Maybe I am just missing it, but the hoop you used doesn't appear to have any 'teeth' for the belt, having any slippage?
I am also very curious, where you got that hoop from? It almost looks like a 20 inch wheel that you modified, which would be friggin awesome. Did you make it or buy it or whatttt?

Have you looked much into aerodynamics? I've been trying to dream up a way to increase aerodynamics, I once read that simply leaning forward helps. (see 'aero handlebars') 50mph is pretty freakin fast on a bicycle. brnot

Oh and, did you get that belt at mcmaster carr? Hah, I guess I am looking for a guide on how to do what you did, because this is exactly what I have in mind as being best. I almost bought a tanaka 40 a few times.

Felton · Jan 4, 2011

If that belt starts to stretch I bet you could make your tensioner spring loaded pretty easy.

lowracer · Jan 5, 2011

msrfan, Thaks for the info on the impulse pump.
Felton, The belt doesn't stretch much & I got a few holes to choose from.
pinjas, The belt is a cogged V-Belt (notches help it go around smaller sized pulleys). I got this belt from my local auto parts store, but I have bought belts off eBay & Mcmaster Carr in the past. There is zero belt slippage once tensioned correctly. V-Belts grab the pulleys on the sides & not the bottom surface. There is plenty of friction there to drive a low powered vehicle. Heck they drive car a/c units & power steering pumps...The hoop is a 'Whizzer Sheave' that I bought new on eBay from a Chinese seller for like $30. He still has them listed now if you need to get one. They fit perfectly without modification on 26" & 700c wheels as long as you have 36 spokes & bolt right onto all the non-drive side spokes. Very secure & no spoke breakage here...
Leaning forward helps alot on a bicycle. I ride pedal bikes too & my fastest bikes are the time trial setups with the aero bars. On the MB's, I pick up at least 5 mph by leaning forward in the aero tuck. I flip my stem upside down & flip the MTB riser handlebars upside down to get nice & low. I also have the seatpost dropped almost all the way down on this short seattube frame to get way low where the center of gravity is down & the bike is more aero. I had some fully faired recumbents that would pedal along at 40 mph but were scary in the wind. Perhaps a front windscreen like a Zzipper or Mueller wind wrap would be an idea.
-lowracer-

lowracer · Jan 7, 2011

Here are two new pics swing some additional cross bracing for the rack (flat screen tv braces) & using the rear disc brake tabs for additional mounting support for the vertical mount.
-lowracer-

pinjas · Jan 8, 2011

You are one industrious dude. I found Rear Transmission Sheave will fit Whizzer motorbikes - eBay (item 220619134431 end time Feb-03-11 15:30:32 PST) this, I searched on ebay the keywords you suggested, Taiwan made. Thanks for sharing.

How do you like using V brakes? I am pretty set on getting avid bb7 disk brakes, they are supposed to be pretty fantastic brakes from the reviews I have read.

Maybe I am missing it, but I can't tell if you have any lights, or a clutch setup. Isn't a clutch super necessary, or how does that work?

lowracer · Jan 8, 2011

pinjas,
Yeah thats the exact whizzer sheave I bought from this seller. Good stuff.
I use an Avid BB7 on the rear wheel of my other MB (full suspension Rocky Mountain RM7) & a Hayes hydraulic disc up front with the largest rotors (200+ mm's). The BB7 is awesome & easy to set up & maintain since its a cable brake. I like V-Brakes too & have used them for years on many bikes. The trick is to set up the v-brake pads correctly with toe in. I am only running one brake on this MB on the front wheel. It is one very powerful brake & I'm ok running just the one.
-lowracer-

corgi1 · Jan 8, 2011

Rear Wheel Assy will fit Whizzer Motorbikes - eBay (item 220571610432 end time Feb-06-11 20:48:33 PST)
in the motor bike part of the store there is what looks like a rear wheel w/ the sheve already on it,complete ,26'',12 guage spokes,,,,$84 +$34 sh

lowracer · Jan 9, 2011

pinjas,
Oops forgot about the last part there.
The centrigugal clutch comes from Max Torque for $49.99 on eBay (pulley clutch)
The V-Belt is an AX notched V-Belt (notched makes it easier to go around smaller sized pulleys)
-lowracer-

lowracer · Jan 9, 2011

I dont ride at night, but I did install the rear rack mount for the Radbot 1000 rear flasher that I run during the day on my road (pedal) bikes for added safety.
The Radbot 1000 is a very bright & noticeable light (1Watt) for day or night riding.
-lowracer-

scotto- · Jan 10, 2011

You wanna race for pink slips?

J/K......it just wouldn't be fair! Very nice rack (I love saying that... lol) by the way.....did you use any steel from your front rack, or build this one from scratch also? Great job with no welding....impressive. dnut

lowracer · Jan 10, 2011

scotto-
I re-used the vertical struts, but did new horizontals much longer. I could have used the old ones but they are beginning to look like swiss cheese with all the holes I drilled in them & I was looking for more strength going right to the seatpost mount. BTW, your engine & rack look impressive. My bike doesnt have a pink slip...lol. Speeds over 40 are downright scary on my rig.
-lowracer-

scotto- · Jan 10, 2011

lowracer said:
scotto-
I re-used the vertical struts, but did new horizontals much longer. I could have used the old ones but they are beginning to look like swiss cheese with all the holes I drilled in them & I was looking for more strength going right to the seatpost mount. BTW, your engine & rack look impressive. My bike doesnt have a pink slip...lol. Speeds over 40 are downright scary on my rig.
-lowracer-

Yeah, you did a very nice job, your design looks sound.....I'll bet is goes plenty fast too! Does it wheelie? Just be careful if it does..... .wee.

lowracer · Jan 10, 2011

scotto-
It doesn't wheelie with the gearing I got it at. Its more set up for top end.
3" pulley clutch
15" Whizzer sheave
25.25" tire
@ 3000 rpm= 45 mph
@ 3600 rpm= 54 mph
Using the gear calculator
-lowracer-

Noahbalboa · Mar 19, 2021

Id like to do this with a Rungu E bike and a small 6.5hp diesel motor to create a kind of hybrid diesel bicycle. Do you think this same set up would work or should I try something different

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