Broken dropout due to weak jubilee clip

[cwah]

Hello all,

My Q100H 260RPM overvolted to 54v broke my jubilee clip for the second time. The first time I was lucky and heard about the metal wobbling around.

But this time, I heard a big clack, like the one you hear when a bone breaks.

And here's what happened

The clip broke, and maybe the plastic prevented me to hear about that?

So now... 2 questions:
- Shall I forget about jubilee clip put on torque arms to fork? If not, what are the better than stainless steel clip?
- And shall I save the fork?

I'm trying now to add 2 torque arms and see if the fork can be saved

 

[Drunkskunk]

Your fork is dead. I'm Glad you are not.

I'm not sure how many times it's been said on the forum that running a hub motor on a suspension fork is a bad idea, or that running high power on an alloy fork is a bad idea, or that running a front motor without torque arms is a bad idea, or how many times cwah needs torque arms, but I'm sure it's been more than twice.

I'd give advice, but it's clear that as long as you have been a member here, you have not taken anyone's advice on how bad of an idea what you did was.

Anyways, Glad you're not hurt. Hope you get back on the road soon.

 

[bowlofsalad]

I don't think I've ever heard of a jubilee clip before. Looks like little more than a hose clamp. I am not sure how you can use that alone as an alternative to a torque arm, or maybe there is more to this that wasn't meantioned. If all you were using is some fancy hose clamp as an alternative to a torque arm, that'd be insane. If someone told you that was a good idea and it failed once, why did you proceed to do it again?

Looks like you were lucky not to end up on the ground.

In any case, my advice for anyone looking to retrofit a bicycle into an electric bicycle is to look into doctorbass torque arms.

They have a phrase, "Penny wise and pound foolish". I don't know if you were aiming to save a few grams or a little currency to avoid setting up a reliable dropout option, but now you probably have garbage forks, wasted time and effort and money. Seriously consider the doctorbass torque arms, nothing else is as good short of fabricating a solution yourself. https://www.endless-sphere.com/forums/viewtopic.php?f=31&t=29129

Do -not- consider getting the closed mouth torque arms that go over the axle, they are a curse in disguise and offer almost zero advantages.

 

[cwah]

I had a torque arm!!

I am talking about the jubilee clip that maintain the torque to the fork:

if the jubilee clip breaks, the torque arm is useless!

In my case, a jubilee clip broke first, i replaced it with a stainless steel hose clamp hoping it would be stronger but it broke too!!!!

 

[beast775]

Cheap hose clamps are a very bad idea with torque.

 

[fellow]

Sometimes, it is possible to found lower fork parts at http://www.aliexpress.com and http://www.ebay.com. Maybe you can repair it?

 

[d8veh]

I had double torque arms on a 64v 30A BPM in an aluminium fork. The arms were properly anchored to the disc mount on one side and a bracket on the other. It worked fine, but months later when I took the motor out to try on another bike, I found that both drop-outs had popped. Everything was still held tightly in place by the torque arms etc. I would now only use steel forks for a front motor of anything more than 36v 15A.

You can sometimes find cheap Zoom forks on Ebay that have steel lowers. I can't see any at the moment, but I found these:

http://pages.ebay.com/link/?nav=item.view&id=271826762748&alt=web

 

[arkmundi]

Strange, I just lost the dropouts in the wreckage after an axle spin-out, but effected a repair that you may find useful.. See my MAC 10T, OSN A123 48V on Trek Shift 3 thread, along with a vid of some of those repair details.

Hello all,

My Q100H 260RPM overvolted to 54v broke my jubilee clip for the second time. The first time I was lucky and heard about the metal wobbling around.

But this time, I heard a big clack, like the one you hear when a bone breaks.

And here's what happened
img]https://dl.dropboxusercontent.com/u/5905557/bikes/cheap_disc/2015-04-11%2020.55.32.jpg[/img]

The clip broke, and maybe the plastic prevented me to hear about that?
img]https://dl.dropboxusercontent.com/u/5905557/bikes/cheap_disc/2015-04-09%2023.52.56.jpg[/img]

So now... 2 questions:
- Shall I forget about jubilee clip put on torque arms to fork? If not, what are the better than stainless steel clip?
- And shall I save the fork?

I'm trying now to add 2 torque arms and see if the fork can be saved

So, yes, try to save the frame by doing a dropout repair and use torque arms on both sides of the wheel which will in part replace the dropouts in taking the forces generated. Best!

I would now only use steel forks for a front motor of anything more than 36v 15A.

I still ponder what went wrong with my eBike build. Sometimes I attribute the wreckage to Trek, which uses aluminium throughout the frame, including the drop-outs. Or as alluded to in the write-up, it may be the hose clamps to the Grin torque arm that loosened. Or maybe a bit of both. Certainly, front or rear, steel is better than aluminium for eBikes.

Cheap hose clamps are a very bad idea with torque.

I agree. Did you experience this or know of others who did?

 

[dogman dan]

He's a lot like me, reads, but then does his own thing. That's cool. 90% of what I write, I know will be ignored. But hundreds of others will read it and learn.

For use on an alloy suspension fork, you need two torque arms, and they must fit the motor axle very tightly. I put about 5,000 miles on a 1000w motor, using two grin torque arms with no broken forks. I did select my hose clamps very carefully, there are some very cheezy ones out there now days. You might be better off to get some strong metal strap, and a bolt to secure the TA. But a tight fit, no slop!

Some other modifications might be needed as well. Did you have c washers? If not, that likely cracked the fork, which then gave way as soon as your torque arm rotated. Just tightening the nut without c washers will create a crack on an alloy fork. It also helps to deepen the dropout notch some, if the motor has a 14 mm axle. I think yours likely has a 12 mm. I think it's quite possible your assembly resulted in the nuts loosening, then you were relying on just the one clamp. That's not going to work for long, the nut must stay tight as the first line of defense.

Those motors with 12 mm axles have short flats on them, so the axle often rotates in the torque arm. This means your torque arm has to fit even tighter.

 

[chilledoutuk]

Most likely the cast alloy dropouts broke and then the torque arm became your dropout and the jubilee clip broke due to the huge load.

If i had to use a cast aluminium fork i would machine it so that the slot is wide enough to not take any torque until the torque arm is wound up.

The problem is that cast aluminium its so brittle that they cant take any deformation before cracking which means your torque arm cant protect it very much unless its litterally welded or bolted to your frame and the fit on your axle is super snug even then under high power the deformation of the torque arm might be too much for the dropouts and they snap.

 

[docnjoj]

+1 to above. My choice is simple. Only use steel forks and double torque arms. I repeat myself. Again And Again.
otherDoc

 

[spinningmagnets]

May I use that pic of the snapped drop-outs?

 

[amberwolf]

There's another pic of snapped dropouts you can use over on my X5304 "kit" thread.

FWIW, cwah, you can save that fork *and* prevent future problems by making tubes with clamping dropouts on them. IIRC, John in CR did so a few years ago, and has info and pics in one of his threads from that time.

I plan on doing the same with what's left of my Manitou Skareb fork at some point.

 

[cwah]

Hello,

I already dismantled the bike. I don't think I'm going into the hassle to save the fork. i think it's a lesson on not trusting jubilee clip and not using aluminium fork.

Yes you can use the picture

Will have the motor kit for sale soon

 

[arkmundi]

Hello,

I already dismantled the bike. I don't think I'm going into the hassle to save the fork. i think it's a lesson on not trusting jubilee clip and not using aluminium fork.

Yes you can use the picture

Will have the motor kit for sale soon

What do you mean you're selling your motor kit? Because you're getting out of eBiking? Or going another direction?

 

[dogman dan]

I'm still very curious whether you had C washers in the cup of the dropout. ( or just any washer that fit inside) Lack of them would have been an almost certain fail. Nut pressure alone on an oversize washer on alloy suspension forks alone will crack the dropout.

If that was the case, then for sure, everything was eventually hanging on one hose clamp.

 

[arkmundi]

I'm still very curious whether you had C washers in the cup of the dropout. ( or just any washer that fit inside) Lack of them would have been an almost certain fail. Nut pressure alone on an oversize washer on alloy suspension forks alone will crack the dropout.

If that was the case, then for sure, everything was eventually hanging on one hose clamp.

You talking to me, or cwah? The MAC kit came with inside washer, their square washer which fits the axle and the axle nut. Had all those on. After my spin-out and damage, I fixed everything and took my first ride yesterday. Beautiful sunny spring day! What a nice ride.

 

[cwah]

I'm just selling this front drive as I have too many motor anyway. I'm thinking to specialise in rear wheel which would be simpler. But I do not plan to stop.

And yes I had washer on it

 

[cwah]

I'm just selling this front drive as I have too many motor anyway. I'm thinking to specialise in rear wheel which would be simpler. But I do not plan to stop.

And yes I had washer on it

 

[John in CR]

Here's one way to save the fork...clamping dropout sleeves. They're steel tubing with a clamping dropout welded to them. I did it to create a clamping dropout on a motorcycle fork which has no dropout.

 

[Cyclezee]

I had a torque arm!!

I am talking about the jubilee clip that maintain the torque to the fork:

if the jubilee clip breaks, the torque arm is useless!

If the torque arm is fitted correctly as shown in the photo above, the load is transmitted to the chainstay, the Jubilee clips prevent lateral movement of the free end.
These have been tried and tested with very powerful motors.

 

[dogman dan]

Well, maybe.

Lots of cheap defective hose clamps (jubilee clip) are out there now. They definitely are not made like they used to be. More and more, I recommend fabricating a steel strap and bolt, preferably two like the clamps in the picture, to hold down a torque arm.

But the torque arm is not why most people break an alloy front fork, the more common problem is not using a c washer. Without the c washer, as soon as you torque down the nut, you crack the fork.

But in this case, the culprit seems to have been a cheapo hose clamp.

 

[teklektik]

Gee - where have I seen that design before?

 

[LewTwo]

I don't think I've ever heard of a jubilee clip before. ...

Ditto, so I looked it up: https://en.wikipedia.org/wiki/Jubilee_Clip
It seems to be a country specific "Brand Name" for a worm drive hose clamp.

I wanted something a little less tender. I used steel straps intended for mounting bicycle racks (supplemented with some shrinkwrap and neoprene pad).

For suspension forks you need something a bit larger (1.375 to 1.5 inches). Try looking for 1 3/8" (35mm) motorcycle muffler clamps.

Seat post clamps are an alternative as well. This one has a 34.9mm ID.

There are also some clamps intended for mounting turn signal lights and such on motorcycle forks.
These may have IDs between 1 to 1-1/2 inches. These might be useful for suspension forks.

Hose clamps are a simple cheap solution without regard for size or shape of the frame piece they must enclose. There are lots of things to use rather than hose clamps when you know exactly what you are dealing with. Think outside the box 8)

 

[Cyclezee]

Gee - where have I seen that design before?

Agreed,

There are similarities between the Cyclezee V3 torque arm and the Amped bikes one, they both do the same job, the biggest difference is that ours are available. :wink: