Dropout problem question

Hi,

I currently ride a 79V ebike on a HS3540 with a 65A rated controller. So far everything has been going ok, with some minor hiccups and fixes needed, however I think I've now seen something quite worrying.



As you can see, there is a fair amount of give in the dropouts. I have taken the wheel off occasionally for some work, however I always used two grin tech supplied torque arms on both sides of the dropouts (however I've only been using one since about 2 weeks ago as I lost the nut.) So I'm not sure what to do now, would it still be safe to ride on two torque arms, or is the situation more dire?

Thanks,

Well, It's pretty clear that even with the TA's you are getting some movement. It's pretty worrying to ride a bike with a potentially cracked dropout.

Then, I'm assuming at times you are going 40 mph on it. You surely can. I think you need to start shopping for a new frame pretty darn soon. And I would not be comfy at all going fast on that one. I just have had enough experience with how easy alloy cracks once you bend it some.

The your teeth depend on it question now is, are those dropouts just rounded out, or are they cracked?

IMO, the grin TA's are a great design, but I don't believe they are really adequate for 3000w plus. You are running a theoretical 5000w. I run 2000w on some that are even thinner, but at 3000w that axle really starts a rockin. 3000w on up, I think it's time to go to pinching dropouts that never allow any movement, till the day you twist the axle right off.

Are you using regen?

5kW is a LOT of power without clamping TA's.

No I'm not using regen.

From what I can see, I can't find any cracks within the dropouts. With power, I usually never go over 4kw and scarcely above 40mph although I do occasionally reach that speed.

What exactly is 'pinching' dropouts and 'clamping' torque arms.

Thanks

This is a decent thread -

http://endless-sphere.com/forums/viewtopic.php?f=4&t=53528&p=796606&hilit=pinching+torque+arm#p796606

There's plenty more but that's what a quick search returned.

Some call 'em pinching, some call 'em clamping. No difference - the point is that there's no way for the axle to rock inside the dropouts when using this form of axle attachment to the frame dropouts.

Of course, high power hub motors relatively soft axle may eventually fatigue and fail.

I would stop riding on that dropout. Too risky even at low speeds and then you will be stuck on the rode. Time to get a new drop out. Make sure your dropout holds the motor securely. Check often the condition of the drop out for cracks and metal fatigue. Ideally after every ride.

Go easy on the accelerations and use weak to no regen to prolong dropout life. Make sure the securing but is on tight. Even the dropout will fail if you have a loose nut.

You need torque plates which are mechanically secured ( bolted, etc ) in some way to the frame, in order to ensure that they have no 'give' whatsoever.

Anything that is clamped down with water hoes ties is decorative at the kind of power level you are running.

I make mine as such for my high power bikes; using whatever hole is available near the dropout ( usually rear rack holes, disc brake holes, or in some instances, i have literally drilled a hole into the frame if the dropouts are particularly meaty. )

You can make these with an angle grinder and file, btw.

Torque arms suck. If you're going to put a motor in aluminum dropouts, you need something with 0 give like torque plates epoxied and bolted to the dropouts so there's no give in them. This is just my opinion since I've never used aluminum dropouts or any type torque arm or plates on my bikes with steel dropouts. I run a 1000W motor on 24s lipo and 40A controller using regen and have never had a problem with steel dropouts. I won't buy a bike with aluminum dropouts I plan to put a motor on for this reason.

:lol: I have seen a shitload of TA's that do suck on this forum. Some guy the other day was all stoked on using a 10mm wrench. That idea died 5-6 years ago. And like I said, over 3000w exceeds the designed limits for Grins universal TA. It's not one that sucks, it's just been taken beyond it's limits.

Looking again at that pic, it does look like you have the room to bolt on a non pinching TA, of the type Neptronix showed in those pictures. Neptronix torque arms never suck.

You might even find that you can devise a way to bolt the grin TA right to the dropout plate. The key thing is if your TA cannot wiggle, then you have a better chance of twisting off your axle with 4000w. For damn sure, hose clamps are not for 3000w and more.

Look at the inside of the alloy dropouts for damage there too, If your axle shoulders now dig into the dropout, it will allow the nut to loosen. Then you get your rotation going big time.

Whether you use a bolted on torque plate, or a pinching type, the whole deal is you have to have a tight fit. If you buy a TA, and it fits loose on the axle, you are doomed running 4kw. The allowable movement at that power level is zero.

One nice thing about a pincher, is that it holds regardless of the condition of the dropout. Maybe you have enough space there to put a pinch type on the left, and something like Neptronix does on the derailleur side.

I like the sound of the torque plate, I think I'll have to look about designing and making one soon, till then, I'll leave the bike out of action

Thanks everyone for your help