Springers and electric motors...?

[id5000]

Hey everyone!

I've heard that a springer fork and a wheel with an electric motor on isn't a very good idea... but I don't understand why not. Could anyone perhaps help shed some light on this?

 

[cobrafreak]

Never heard that one before.

 

[maxshnel]

I've not heard of anything specific. I would say it's not so much a bad idea as one that has to be thought through. The immediate concerns that come to my mind if you're talking about a front hub motor and a schwinn style cantelever springer are: What is the motor forcing against besides the spokes? What's preventing the axle from spinning? Is there any force involved that could cause the springer to twist? How does the force applied by the motor interact with the action of the springer? How's the weight distribution with a rider on the bike / motor in the front wheel? Does it feel strange to be pulled rather than pushed? Does the springer decrease traction on the motorized front wheel? et cetera. I would not be surprised if someone somewhere has a front hub electric motor set up in a springer fork performing flawlessly. That said, it's not an idea i'm particularly drawn to except maybe in a dual motor set up (two wheel drive plus optional human power).

 

[K-dregg]

Well springers is due to its construction a bit weaker when loaded sideways, thats all that comes to mind..

Kul att se fler svenskar här för övrigt!

 

[DougC]

The motor torque might push the lower linkage one way or the other, compressing or raising the suspension sag. It would depend on how you had everything hooked up though.

Also a lot of the cheaper lowrider-style springer forks are built pretty flimsy to begin with. The stress of a hub motor might not kill them, but isn't likely to do them any favors either.

 

[wheelbender6]

I posted this question on a site once and was generally advised not to combine a springer with a front electric hub motor. Good brakes are tough to mount on springers unless you get one of those springers on EBay that has bosses for mounting a mountain bike brake or you get a disk adapter kit from VeniceMotors or Chainganglowrider (I use a drum brake with my springer fork).
I think you will be OK with a front hub motor on a springer if you have a good torque arm and can mount a good front brake.

 

[Philphine]

i remember reading something about that, but it's been a while. it was something about wheel hop and/or efficiancy putting power to the ground.

 

[id5000]

Well, what I had in mind is a Monark style springer like this one here:
http://1.bp.blogspot.com/_Zst7s87lZIk/TJdTkDXvLLI/AAAAAAAAAjk/l8ZVOfiaySA/s1600/springer.jpg

The dropouts on those babies don't look too thick though..


Here's what the bike looks like atm:

 

[Frank Lee]

o.

 

[deorman]

That type of fork is notorious for insufficient crown welding, although http://venicemotorbikes.com/ sells an upgraded version.

 

[DougC]

That type of fork is notorious for insufficient crown welding, although http://venicemotorbikes.com/ sells an upgraded version.

I was one of the early purchasers of a pair of those forks. It had a few issues.
--the steerer tube was slightly too-small diameter and the lower headset bearing needed to be shimmed, all modern ones were too big
--the axle dropouts were only 5/16" diameter, when modern axles are all 3/8" thick
--the dropouts were only about 80mm apart, when all modern front wheel axles are 100mm wide. You cannot simply "flip" the lower bolts to put the dropouts outside the fork blades, due to the odd type of bolt used.

Particularly the last two points above made me think it may have been intended as a drop-in replacement for the vintage fork--since no modern front wheel would fit at all--and if so, it may have been built correctly. I'd bet the original company would have angered a lot less people if they had explained that better on the website, since people thought they were buying a drop-in part and it would not fit on any modern bike without some modifications.

I don't think trying to put a hub motor on it would be a very good idea myself, since I can't see how you could do it without having the motor's torque compress the suspension.

The fork crown welding on mine held just fine, FWIW. I rode it two summers before getting rid of it. It's not a heavy-duty part, and should be treated accordingly. If you are planning on buying one for a modern bicycle, you may want to ask around to see who has bought one lately, to find out exactly what you'll need to deal with.

 

[id5000]

Thanks a lot for these answers!

It'd be nice to have some kind of suspension - the bicycle roads here in Stockholm often leave a lot to be desired sadly. I guess I'll have to go without; like you said DougC, the torque should just compress the suspension. Maybe on my next bike.. =)