Front hub motor touching fork, what to do?

[jacks3]

Hi, I have a Carrera Crossfire and recently purchased the Dillenger e-bike conversion kit (700c wheel). Unfortunately, when I mount the new wheel and tighten the nuts, the motor is firmly pressed against the wheel and it can't rotate at all (I've circled where it touches it on the photo). I tried filing a bit off the fork where the motor touches but without any effect, I think I'd have to file off quite a lot to prevent it from touching and that would compromise the structural stability of the fork.

What do you suggest I should do? If there's no way without changing the fork, what fork should I buy? I'd be looking for something cheap but that would be safe with the additional stress on it from the motor, I don't necessarily need suspension.

 

[RobN]

Im new here myself and no expert but does it need a washer on the inside of the fork up against the hub to keep it off the forks?

 

[Nealh]

You need to move the washer that is outboard ( behind axle nut) and place said washer inboard of the Anti rotation washer as I have inked below.

 

[jacks3]

Wow, thank you very much, it fits perfectly now. I feel so stupid, hopeful I haven't compromised the fork's strength with the filing I did.

 

[Nealh]

Wow, thank you very much, it fits perfectly now. I feel so stupid, hopeful I haven't compromised the fork's strength with the filing I did.

You did the right thing and asked because you didn't know or realise.
Put a bit of black paint on the filed fork it won't be compromised.
At least the Crossfire should be reliable now.

 

[jacks3]

Cheers, I'll give it a spray with a bit of paint.

 

[stevenatleven]

I wanted to ask if you had a torque arm fitted on the other side of the fork not in your picture ?
The reason i ask is I have a similar front motor and the axle on the cable exit side is longer and the only place I could fit a torque arm

 

[Andy-Mat]

Im new here myself and no expert but does it need a washer on the inside of the fork up against the hub to keep it off the forks?

Good post.

Andy

 

[jacks3]

I wanted to ask if you had a torque arm fitted on the other side of the fork not in your picture ?
The reason i ask is I have a similar front motor and the axle on the cable exit side is longer and the only place I could fit a torque arm

No, I don't, they weren't included in the kit, but I was wondering if I should get them for extra safety.

 

[Andy-Mat]

No, I don't, they weren't included in the kit, but I was wondering if I should get them for extra safety.

If the motor gets slightly loose and turns on its axis, the example I once saw had ripped out all the motor and hall effect sensor wiring from the hub.....you do not want this to happen....

Andy

 

[stevenatleven]

My thoughts as well, alloy forks without torque arms are a risk. Esp as you filed them too.
I would fit a set where you have all that axle on the cable side.

 

[jacks3]

Alright, then I'll definitely get them installed just to be safe. Where would you recommend to get them from in the UK? Would the ones on ebay for £10-£15 get the job done?

 

[vfr400]

That doesn't look at all right to me and it worries me. I think we need to take a couple of steps back. Are your drop-outs dimpled (lawyers lips) on the outside? If so, do you know the rule that nothing outboard of the drop-out should overlap the surface around the dimple? If the nut or washer overlaps the edge around the dimple and you tighten the nut, the drop-out will pop and you'll need a new pair of forks.

 

[jacks3]

No, I didn't know that but now when I think about it makes sense. The nut does overlap the dimple, I've attached a photo. Have I damaged the forks by tightening it like that, I haven't noticed anything obvious?

 

[Andy-Mat]

I have to say that this is fast becoming one of the most interesting and informative topics on Pedelec recently.
My personal thanks to all "posters".
Andy

 

[stevenatleven]

i agree with vfr400, what i would do. spacer + tab washer inside the fork dropout and if the wheel is running free and centered. (you might have to look at both sides) you need to fill the lawyers lips gap with another tab washer, then when flush then add a torque arm and then finally the locking nut.
I think the torque arm kits you get off ebay for under 10 quid are fine.

 

[WheezyRider]

I had a similar issue with my front hub motor. Screwfix sell 12mm ID stainless steel washers and you can use one or more of these to get the spacing right, so the hub doesn't foul the forks. Also as VFR said, you've got to have a washer on the outside so the nut doesn't press against the lips on the outside of the fork that prevent the wheel coming out of the forks if the nuts are loose.

The outer diameter of the 12 mm washers was too large in my case, they fouled the safety lips, so I had to use the 10 mm washers that came with the bike's original wheel and file out the centres until they fit on the motor axle. Then the outer nut seated properly and it all ran fine.

 

[WheezyRider]

My thoughts as well, alloy forks without torque arms are a risk. Esp as you filed them too.
I would fit a set where you have all that axle on the cable side.

The part that was filed was just on the inside arm of the fork where the hub was fouling. If the drop outs are intact, you really shouldn't need torque arms for a normal 250W hub motor. The recessed washers that come with the motor should be enough. As it is, after the bike has got wet a few times, you will probably find it hard enough to get the wheel out again from the forks!

 

[Andy-Mat]

I had a similar issue with my front hub motor. Screwfix sell 12mm ID stainless steel washers and you can use one or more of these to get the spacing right, so the hub doesn't foul the forks. Also as VFR said, you've got to have a washer on the outside so the nut doesn't press against the lips on the outside of the fork that prevent the wheel coming out of the forks if the nuts are loose.

The outer diameter of the 12 mm washers was too large in my case, they fouled the safety lips, so I had to use the 10 mm washers that came with the bike's original wheel and file out the centres until they fit on the motor axle. Then the outer nut seated properly and it all ran fine.

Simply cutting a flat off the outside of the 12mm washers to clear the safety lips, with a small hacksaw, might have saved you some work, and you get the larger area coverage as well, from what is left of the larger washer.
Or a Dremel cutting disk to shape the cut even better. I love Dremels!
I always look for the lazy way out of a problem!
Have a great day.
Andy

 

[WheezyRider]

Simply cutting a flat off the outside of the 12mm washers to clear the safety lips, with a small hacksaw, might have saved you some work, and you get the larger area coverage as well, from what is left of the larger washer.
Or a Dremel cutting disk to shape the cut even better. I love Dremels!
I always look for the lazy way out of a problem!
Have a great day.
Andy

Given time I could have CNC fabricated a perfect washer...but I just wanted to get up and running and I had a small circular file to hand...