Avoiding rounding dropouts?

[dnmun]

i use JB Weld for epoxy. you can buyt the cheaper stuff from harbor freight, but the JB Weld is the real deal, imo.

i'm not too concerned about these huge torques you guys worry about. i make it a point to use the dropout to hold the axle tight and then add the torque arm as insurance in case the axle nut becomes loose. you know right away when the axle is getting loose. so no need to go hard if you know it is loose anyway.

a serrated washer or serrated faces would be ok, but i don't think it is needed since i just don't see that much load applied, and for me the two pieces are at right angles so it is not able to twist like ray did with his set out straight like that.

i am really glad that jason has started including this in his ebikekit.com finished kits. making sure that people will have a good first experience with their ebike is so important. for those of us who tinker, fixing stuff is the fun of it, but for a lot of people, they just panic when it comes to doing stuff and get really flustered and overwhelmed so what jason is doing to make sure it is reliable is what will allow people who buy his kits to keep riding them for years rather than just put them aside after they break the first time.

plus he includes the spoke wrench, and i bet eventually he will have video on his site for people to follow how to tighten their spokes just right. more power to him, that's where people will go to figure out how to tighten them.

but it means we won't be getting twistoffs from his customers on the 'for sale' page, like we do with the goldenmotors that twist off because they don't have torque arms in the kit. that is how i got my goldenmotor.

 

[icecube57]

Im not so worried about my dropouts failing now. But I still dont fully trust them due to the tremendous torque the dropouts are subjected to. Im using two super tight torque arms They are not loose. I can barely get them off the axel when working on the motor.

That is one key thing. If there is any movement when seating the motor in the drop out .. thats a disaster waiting to happen. Using that Crystalyte J arm saved my but but kinda ruined the axel a little bit because it was so loose around the axel. When i snapped the drop out on my magnesium fork it held it on but It very slighly partially rotated causing the threads to get smashed. But it kep the wheel on and im thankful.

Im personally worried about spokes. I hear them shift more and more since I went to over 80v. But over 2500 miles and none have broke. Ive broken 2 cheap rear wheels due to spokes breaking. Another wheel had bad bearings and couldnt be repaired. The last wheel was a very solid and it came stock with my bike. The bike rack fell off my car and I pringled the wheel. I just bough a Mavic wheel that has flat spokes... rides super smooth and quiet and its a double wall rim so it should hold up alot better. It seems like its under more tension than a traditional wheel.

Sorry for getting off topic. All i can say is install a torque arm.. or two... or 3-4. If i ever change out my phase wires im going to buy two more ams and put them on the other side of the axel and have 4 total... My build is a face plant waiting to happen...lol

 

[Ray007]

Thanks Mike and everyone else for the comments regarding torque arm suggestions. I would have commented sooner but have been busy with family issues and sickness (we think Swine flu but not sure). Over it now.
Anyways, the bike has gone over 260 miles now commuting and no slippage for the setup I showed in the last pic. On an interesting note, after the ten or so battery cycles, I ramped up to 22 or so Amps max running current on the CA and found about the same peak current spikes of around 50 Amps (which as still too fast for me to see in the display but the CA logs it as a peak current..) Electro-ride claims it is a minor issue with the Clyte/BMC combination such that the CLyte is not quite fast enough to slow down the inrush current which the 600W V2-T motor asks for initially. Yeah - that's what I figured.. They said they are looking into some future improvement... But then this is really for another forum which I may look into once I get back to riding.
I will pay attention to several of the suggestions, and definitely pick up some JB weld in case I need it.
PS - I urge everyone to use Kevlar tires for commuting, nothing less.....I think you know why I'd mention this. It was NOT a fun morning I had in a certain WalMart parking lot.
cheers,
Ray

 

[DerekG]

Ray 007, can you please explain one thing to me?

You mentioned earlier that your motor was putting 300-600 ft lbs of torque on the dropout, however, on ebikes.ca simulator at 50 amps and 72 volts a standard motor like a 9c puts out only 80 lbs or so of thrust.

I would assume you are talking about rotational torque vs vehicle thrust, however, if you could clear it up for us new folk that would be great

 

[Ray007]

Yep ... "Lbs thrust" is certainly different from Ft-Lbs. I believe they are using the actual wheel diameter and then giving you the force at the ground. That's a nice calculator they have - thanks for the notice.
I had to estimate my torque values based on low speeds worst case. The problem is I really don't know when the current spike occurs when I apply the throttle. I've been guessing about 4-6mph. If you use 1 mph things start to go through the ceiling for torque. See the screen shot of the spreadsheet I through together. Yes, I called BMC to get the formula and then found it online as well. If I was motivated and had tons of time and money, I'd get a current meter and connect it to a storage oscilloscope. Probably not gonna happen.

 

[317537]

I was thinking the length of those torque arms displace the torque where they connect and this is ok for a lesser hub, but if you were to have a longer arm you could have the torque displaced right up close to the fork welds, erm maybe not that long. On lighter forks a longer arm would have much better strength as you're not putting the torque into an all ready abused part of the forks. Longer torque arm = more leverage too. Its just a few people are still concerned with using regen on front hubs.

I just look at the turning circle radius and where it actually displaces the torque with current front hub torque arms and it looks a little scary to me. I think a larger radius wouldnt hurt.

Hmmm. This converts the rotational torque into upward torque. It wont flex the fork ends circular like a standard arm will but it has the effect of pushing the wheel out of the dropout or pulling the wheel into the dropout in respect of acceleration or braking with regen. If a wheel nut comes loose it is rendered usless, where as rotational arms keeps strong.

This one place all the rotaional torque right at the forks end and will still have the effect of pushing the wheel out of the dropot when braking heavily.

This one, although rear hub, wins the award IMO as it is rotational and almost as long as the radius of the wheel. By doing this you you force most of the torque right back onto the arm where it connects to the axel and place little stress on the forks or frame.