Snapped fork dropouts

General Discussion about electric bicycles.
User avatar
ddk
1 MW
1 MW
Posts: 1808
Joined: Nov 04, 2011 5:37 pm

Re: Snapped fork dropouts

Post by ddk » Dec 17, 2017 6:53 pm

adamsavage79 wrote:
Dec 17, 2017 5:34 pm
Ok ? That's for the rear.. I have a front wheel motor....
My opinion, as if you needed an extra:
-I'd only consider mounting a low-powered geared-hub motor on a cheap suspension fork.
...and I have... many times.
But I've also added 1000W+ with regen braking on custom designed suspension forks, one of which I've been riding for 6 years now.
-cast metal (steel or aluminum) can be either the best or the worst thing ever and any flaws in the casting will fail catastrophically (as your fork did). I wouldn't trust any casting to support the kinds of forces heavy DD motors can generate, including just the added mass of the motor in a bicycle fork. Pinched tube forks are better for mounting motors... because you're guaranteed the tube was not cast !
Even properly installed torque arms won't solve the problem as you've presented it. They might delay the failure mode but won't prevent it,and that is the the dropouts are fashioned from cast instead of rolled (metal, whatever metal it is)

You didn't mention what power the controller could support (the elephant in this room) because you might not have had this failure with a 7A (250W) controller... maybe. There's still the question in my mind about the mass of the motor affecting the normal operation of the bicycle's suspension fork.
dogman dan wrote:
Dec 17, 2017 8:44 am
Some will say no way a motor on alloy forks. I just say it has to be done perfect. Even then, you may have what I experienced, the fork will jack forward when the motor is on causing the fork to bind. So with some forks, you have to get off the throttle when you cross the RR tracks, or whatever. Otherwise the fork is pretty close to rigid.

I did many thousands of miles on alloy forks, and never broke a fork. But the motor pull did wear them out fast. Eventually most of them started to do that binding thing. Only the very expensive forks, or very cheap, did not bind eventually.
Yep, cheap headset bearings wear fast... On one of my contraptions I had to replace the headset bearings approximately every 6 months (about $1.50 from the LBS) , eventually replacing the fork when the steerer tube fatigued and expanded under the pressure of the threaded stem thingie.
Had to pound the fork out of the headset tube with my favorite BSO tool, the three pound sledgehammer.
(afterwards welding a new headset tube to the frame because the damage I caused pounding out the steerer tube!)

After all this typing, bottom line:
get a rear motor or a more suitable fork
"How can we play Hot Wheels without lighter fluid? " -Serge

User avatar
adamsavage79
10 mW
10 mW
Posts: 21
Joined: Dec 07, 2017 11:46 pm

Re: Snapped fork dropouts

Post by adamsavage79 » Dec 17, 2017 7:02 pm

motomech wrote:
Dec 17, 2017 5:19 pm
http://www.ebikes.ca/shop/electric-bicy ... rm-v4.html
Y
ou didn't mention what power the controller could support (the elephant in this room) because you might not have had this failure with a 7A (250W) controller... maybe. There's still the question in my mind about the mass of the motor affecting the normal operation of the bicycle's suspension fork.

After all this typing, bottom line:
get a rear motor or a more suitable fork
I'm not sure what the controller is. I got it from power in motion, and I think it's a 20-30A controller for sensorless motor. As for a rear motor, I plan to get one in 2-3 months time. I've had nothing but headaces with this front wheel motor. I thinking of getting the Magic Pie 5 Vector.

User avatar
ddk
1 MW
1 MW
Posts: 1808
Joined: Nov 04, 2011 5:37 pm

Re: Snapped fork dropouts

Post by ddk » Dec 17, 2017 8:40 pm

adamsavage79 wrote:
Dec 17, 2017 7:02 pm

I'm not sure what the controller is. I got it from power in motion, and I think it's a 20-30A controller for sensorless motor. As for a rear motor, I plan to get one in 2-3 months time. I've had nothing but headaces with this front wheel motor. I thinking of getting the Magic Pie 5 Vector.
sensorless controllers are about the absolute worst choice for a motorized front wheel (has to do with occasional juttering/shuttering forces as the controller tries to sync with the motor... again not so much an issue with low-powered systems) Supplier seems significantly ill-informed about this stuff.

good luck on your endeavor!
"How can we play Hot Wheels without lighter fluid? " -Serge

User avatar
adamsavage79
10 mW
10 mW
Posts: 21
Joined: Dec 07, 2017 11:46 pm

Re: Snapped fork dropouts

Post by adamsavage79 » Dec 17, 2017 9:16 pm

ddk wrote:
Dec 17, 2017 8:40 pm
Sensorless controllers are about the absolute worst choice for a motorized front wheel (has to do with occasional juttering/shuttering forces as the controller tries to sync with the motor... again not so much an issue with low-powered systems) Supplier seems significantly ill-informed about this stuff.

good luck on your endeavor!
Well I don't recall the exact controllers model, as it simply says DS on it. It's small, black and fits on my downtube. I told them it needed to be for a 48v 500 watt, sensorless motor. Either way, it's worked well sense about April when I got it. The only downside, is that I learned the other day, is that it's not very efficient and has reduced my range by about 5km or so.

I've learned a lot about how my Ebike works, as I don't have a shop I can bring it to.. It's a custom kit, so I've had to self teach myself everything about it. I don't know as much as you guys, but I find I'm learning almost daily here, all thanks to folks like yourself. :D

I had no idea a controller could reduce the range of my battery, or it would have sync issuses.. This is all new to me, but that's ok. I do know now, and that's what important.

User avatar
motomech
100 MW
100 MW
Posts: 2910
Joined: Sep 11, 2010 12:21 am
Location: Tucson Az.

Re: Snapped fork dropouts

Post by motomech » Dec 17, 2017 9:21 pm

adamsavage79 wrote:
Dec 17, 2017 5:34 pm
Ok ? That's for the rear.. I have a front wheel motor....
It's for wherever it works.
Motomech

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, 2.4 Holly Rollers run ghetto tubeless. 25 mph. Mean Well HLG-320H-48A
https://endless-sphere.com/forums/viewt ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 12S LiPoly elifebike 9-FET 17A controller. 20 MPH.
https://endless-sphere.com/forums/viewt ... 8#p1237928

Post Reply