best fork for front motor?

Hello,

I got my front fork dropout completely damaged by my front q100h motor even with torque arm.

I think it was because its aluminium.

Any recommendation on a replacement fork?

Thanks

Ah, the q100h, light of my life.

Forks come in all kinds of different parameters, materials, weights, widths, sizes, suspension, costs, colors and support various types of brakes. More information is needed. http://www.sheldonbrown.com/headsets.html

I recommend getting some steel forks that suit your needs and weld/epoxy on some doctorbass torque arms. Aluminum lacks a fatigue limit, if there is any play in your setup, the aluminum will eventually crack (as I am sure you've experienced). I am a little bit obsessed with doctorbass torque arms. They seem like such a versatile product at an amazing value for the retrofitter. I know this sounds like an advertisement, but I am no shill. There are a lot of benefits to the design in my opinion, the biggest is their open mouth design. Loosen a few axle nuts and you can get your wheel free from the dropouts in no longer than it took before the torque arms were installed. Great for changing a flat, replacing a tire, truing the wheel and all that.

To eliminate any play potential in doctorbass torque arms, rotate each arm in opposite directions as you weld/epoxy and clamp.

http://www.endless-sphere.com/forums/viewtopic.php?f=31&t=29129

The fork is a lot less the problem, than what you are doing with the c washers and the torque arms.

One thing that could help, is fitting the two piece type torque arm, tightening the bolt, then having it welded in that position. That way it can't rotate at the bolt. Then you can replace the hose clamp with a bolt and metal strap, and it won't slip down the fork.

You might even consider making your own torque arms. so they fit even tighter, and are exactly the right shape for your choice of fork.

If you need 1 1/8 unthreaded, consider Surly ($68 list). Fairly burly and I've had good luck with a 350w conversion and Grin torque arm.

I've had good luck with quality XC suspension forks with 32mm stanchions and magnesium lowers such as Rockshox XC32 or Tora/Recon models. Magnesium is softer than aluminium. This helps the bolts and washers adhere better, creating a larger overall contact patch. You really want to limit the peak torque by setting a low phase current on your controller. Any higher and the tyre will slip anyway. Use torque arms on both sides if you will, but the most important thing is keeping those damn bolts tight at all times. If you think you can't guarantee any of the above conditions, you will be better off with a steel fork.

I have built a number of front motor E-bikes and used STEEL FORKS on all of them. I have ridden them thousands of miles without any problems. The KEY I'd say is proper fit and attention to detail.

Here is one of my early bikes which I used small torque arms screwed to the front rack/fender braze-ons.




On this fork I filed down the lawyer lips to make a nice flat surface. I like to use strong inside washers rather than let the motor shaft butt up against the fork directly.



With my next bike I wanted to leave the lawyer lips intact so instead I filed anti-spin washers for a custom fit.


View attachment 3

Again an inside washer is used and everything is nice and flush.

Here is the wheel from the first (green) bike using the same custom washers on a steel suspension fork.


Here is one of more recent bikes, again with a stout steel fork. On this motor I used some anti-spin washers that fit really nice without modification. They fit into the lawyer lips and extend perfectly into the dropout opening. This motor also did not have a shoulder on one side of the axle so I used a hefty jam-nut instead of the wimpy one they provided.



Also remember to tighten the nuts on both sides at the same time. If you tighten one side only with the other loose you can twist the axle in the dropouts and open them up, or with aluminum actually crack the fork.

-R

This is another of those threads that would be better kept in a single one,instead of spread across at least two. It started here
http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=68514&p=1033252#p1033252

where people were already trying to help you figure out a solution, but you abandoned them there and started this new thread instead.

If this didn't happen, I think that more people would be willing to help others, and solutions woudl be found (and found faster).

amberwolf said:

This is another of those threads that would be better kept in a single one,instead of spread across at least two. It started here
http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=68514&p=1033252#p1033252

where people were already trying to help you figure out a solution, but you abandoned them there and started this new thread instead.

If this didn't happen, I think that more people would be willing to help others, and solutions woudl be found (and found faster).

Click to expand...

Last answer was to recommend me to braze torque arm to my fork to save it. I don't have the equipment so I couldn't go further.


Here I'm specifically asking for a fork for the motor, so it does feel it's a slightly different one.


Thanks for all the answers. Yes steel for is a must, but which one? I'm thinking one with suspension may be better?

It does seem that the Rockshox XC32 fork are the best? I don't know about surly fork (I am in the uk)

cwah said:

Thanks for all the answers. Yes steel for is a must, but which one? I'm thinking one with suspension may be better?

It does seem that the Rockshox XC32 fork are the best? I don't know about surly fork (I am in the uk)

Click to expand...

And the point of my post was to show you there is NO ONE BEST fork. I've used 5 different steel front forks. Again the key is the hardware you use and how good of a job you do on the installation. I haven't even used a torque arm with a front motor for years now and have had no problems.

Only very low-end suspension forks, like the one I show above, are made with steel lowers so you won't find a good one with that "feature".

-R

Surley has some decent steel disk unsuspended forks. I've got one on my Hooligan and it is bog standard for torque arm fitting.

I am riding on my third set of forks for my 800w front hub motor. The motor has over 7000 miles on it now....but I got rid of the non-suspension setup because it was too harsh a ride for me.

So I would recommend a medium priced suspension fork. Extreme attention paid to what ever filing you need to do to center the larger ebike motor axle in the fork (usually about 2mm of careful filing). Patient filing means less problems down the road.

Proper fitting "C" washers to clear the cups on the dropouts for proper fit.

2 Torque arms for safety and proper stress distribution on the fork brace. (I had to go to a second suspension fork because I snapped my first fork brace probably due to the use of a torque arm on one side.



I use 55 foot pounds of torque to properly snug the e-motor axle bolts. I use a torque wrench for the job.

This is my current setup...and I am of the belief that it is the best and safest front fork torque setup on es. I haven't posted much on it because I wanted to ride it for a few thousand miles to see if worked well, and it has. If the dropouts crack open the wheel will stay in place yet comes off quickly and easily when I need to change a flat. They are made out of U-bolt fittings. They were heated and bent in a vice. Some grinding was also done to allow the hose clamps to seat and hold the dropout snug to the fork.





I also have a more advanced prototype that comes from machined parts..... if I ever get around to finishing that project they will certainly be the best front fork torque arms available for an e-bike.

There's these ones, but the drop-outs are in the middle of the tube, so chech that the tube won't rub on the motor.
http://pages.ebay.com/link/?nav=item.view&id=141373971373&alt=web

These ones have inboard dropouts, so should be OK.
http://pages.ebay.com/link/?nav=item.view&id=171351220691&alt=web

Many cheap bikes have steel forks. You just have to hunt them out with the right size steerer. For MTBs, you can get some nice triple clamp steel forks from a Silver Fox. They have bigfoot written on them. You can stick a 1000w motor in them because the drop-outs are about 6mm steel plate.

http://pages.ebay.com/link/?nav=item.view&id=391121655437&globalID=EBAY-GB&alt=web

Thanks D8veh, I want new steel forks but... it would be great if they could be lightweight? Is there such a thing as steel dropout aluminium suspension fork?

No point for me to get a lightweight Q100H if it's to make the bike heavy as hell?

The lighter steel forks don't have suspension. I don't know of any like you want.