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mounting electric front hub on suspension bike

R

Red

Guest
Hi all.

If I mount the front hub motor on my mountain bike with front shocks will it rip them apart? is this something that should not be done. My bike has full suspension so I'm trying to find a kit that will work.

Heres a link to the bike its the top one the [Topkick]
www.kentbicycles.com/bikes_gmc.html
 


J

jerryt

Guest
Red I don't believe you should mount a front hub motor with front fork suspension. I believe you will be OK to mount a rear hub with rear suspension. Rear dropouts on bikes are heavier than front, and can take more torque. Just make sure the drop-outs width will accommodate a hub motor. If you use a rear drive, you can still have front suspension

Just remember that an electric bike will weigh at least 80 lbs and with a rider that weighs 180 the bike has to take stresses carrying over 250 lbs. The GMC you're looking at will probably weigh more.

EDIT: Regardless whether you mount the hub on the front or rear, be sure and use a torque arm.

I recommend you do more research . There are not many people here dedicated to electrical power so visit a couple of forums dedicated to ebikes and bring your knowledge back here. Try this
http://endless-sphere.com/forums/index.php
 
5

5-7HEAVEN

Guest
8) i mounted a 4011 CRYSTALYTE hub on my ROCKSHOX fork and cruiser bike. lots of sideroom. it is imperative that you clearance the dropouts precisely for the notched bearing retainers on the larger axle, to lessen the likelihood of axle spinout.. also, it'd be wise to fab torque arm(s)/axle retainer(s) to prevent spinning the axle in the dropout.

Myron
 
5

5-7HEAVEN

Guest
8) JMO, it's all about rolling your bike out of a deadstart. the best proactive habit you can learn is to at least push off from a deadstart before applying power. the electric motor is leveraging its twisting shaft against the road surface through the tire patch...ANND the bicycle through its dropouts.
it's also important to do so with gas engine friction drive, and good practice for any motorized bicycle.
 
L

Lowell

Guest
Standing starts are the best part of electric motors. Peak torque at zero RPM :)
 
5

5-7HEAVEN

Guest
:cool:ever wonder why, when most high hp cars break their drivetrain, it's at a standing start, launching with full power?
the fork's dropouts are the "Achilles' heel", especially when clearanced to fit the hub motor's thick axle...ANND when the dropouts are aluminum.
it stroked my ego when my quiet, powerful electric motor would pull my cruiser from a stop. much classier than pedalling or pushing off, but not prudent.
 
P

pm

Guest
I agree that you want to be careful mounting an electric motor to a front-wheel suspension. That said, a lot of people have done it - myself included.

I would definitely encourage you to make sure that the front fork dropouts are beefy and made from steel (check with a magnet). Aluminum forks crack and can fail suddenly, steel bends and tends to fail over time.

It's less of a problem with a pedal-first controller (motor starts helping above ~5mph), or one that is a pedal-assist (motor helps when you pedal). Instant-start controllers on larger motors tend to be where the problems are.

On my first bike, I mounted an 800W motor onto a puny steel non-suspension fork on an old mountain bike, and coming out of a stoplight, I gunned it and the motor rolled out of the fork. The wheel twisted, caught in the brake and the bike stopped suddenly and I slammed into the handbars - which left a rather large bruise and was a bit embarrassing and left me stranded several miles from home. Not my finest hour.

My new bike has a roughly 900W motor on a beefy steel fork with an instant start controller. It has a suspension, but that hasn't seemed to cause any problems. I'm sure I have well over 1000 miles on this bike (I ride it 10 miles a day, 3-4 days a week whenever the weather is warm since last summer). It's been fine.

I would highly, highly recommend a torque arm for any motor over about 500W mounted on the front forks. Something like this:
http://www.poweridestore.com/Hub-Motor-Torque-Arm

The rear drop-outs on most bicycles - particularly mountain bikes - are usually much thicker and better reinforced than the front. But even mounted there, I wouldn't recommend an aluminum or alloy frame. Steel is best.
 
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