Hub motor doesn't sit flush in dropouts

[EdwardNY]

I just got my Yescomusa kit today and I noticed that the hubmotor has a very tiny spacing, about 1 mm, to sit flush in the dropouts. The sides of the dropout seem to be OK and is a snug fit. The space is at the very top of the the axle, like it doesn't slide all the way into the dropouts, but by only 1mm, so most of it fits in.

Bike has aluminum frame.

Would this small spacing be a problem if I just left it? I seriously do not want to modify the drop outs.

I am going to be making custom torque arms also.

 

[dogman dan]

Your washers, torque plate etc will fit better if you shave the bottom of the dropouts with a file.

In my opinion, a proper fit includes making sure the center of your axle is in the same place as the center of the smaller diameter bike wheel axle used to be.

You file the dropout about 2 mm deeper, and flatten the bottom some so the bigger radius motor axle fits all the way to the bottom. It's not hard, nor time consuming. Don't take power tools to it though. just do it slow and carefull with a file.

Your old axle was 10mm, now it's 14 mm. If you leave it as is, it's hanging out of the dropouts by 3mm more than it should, half the difference plus the 1 mm gap at the bottom.

 

[EdwardNY]

The axles for my kit are 10mm, but it still doesn't sit 100% flush.

Another more pressing problem. The weel doesn't sit straight when in the dropouts. Kind of off to one side more than the other. Why would this be?

 

[biohazardman]

Some of the motors out there need to have the wheel dished so it will be in the middle of the frame. You can do this by loosening the spokes on one side of the wheel all 1/4 to 1/2 turn and tightening them the all same amount on the other side to pull the wheel that direction. Remember you are werqing from the wrong side of the rim so a clockwise turn, on the nipple, is to loose and a counter-clockwise turn is tighten. Start at the valve so you can remember where to stop. Possibly this is your problem. Is the axle 10mm at the flats and 14 at the round part that does not fit flush? If so then dogman has it right.

 

[amberwolf]

FWIW, unless you have rim brakes, you can often leave the dishing alone; it doesn't affect the ride that much except for no-hands riding, for the most part.

If you don't kknow anything about wheelbuilding, see here:
http://sheldonbrown.com/wheelbuild.html


Unfortunately dishing of hubmotor wheels is a major problem with lots of "brands"; they are often offset to one side or the other (uusally the non-drive side, to the left), because of the narrower width of the spoke flanges on them vs those on a typical rear bicycle hub. Some motors *cannot* be laced so that the rim is dished correctly to sit in the center of the frame, because of how they are designed--to fix this you have to add spacers on the axle to the other side (and sometimes stretch the stays apart at the dropouts, by a few mm).

 

[dogman dan]

Get the file out, and get the axle straight in the dropouts before dealing with the dish. At the minimum, get the axle touching the bottom of the dropouts on both sides. The wider curve on the hubmotor axle will never drop into a slot with a curve for a smaller axle. So you have to shave the sides at the very bottom of the droputs. I'm not even certian if you are dealing with dish, or tilt.


Even with rim brakes, you can adjust the brakes to grab to the right or to the left a mm or two if just slightly off center. You can spread an alloy frame very slightly if you must. just enough for one washer on one side. No more than that though.

If you aren't using disk brakes, it could be possible to shave the axle shoulder down on that side. That could center the rim if the direction you need to go is left. Likely you need to go right though.

 

[EdwardNY]

OK, I didn't do anything yet because I want to remove the annoying chain in the way. Needed to get a special chain tool for that.

I will go ahead and file the dropouts so the hubmotor sits flush. I will then see how it sits.

I notice the spokes on the rim are .160" or 4mm. Not your normal .136. Has anyone noticed this? I guess I would need a special tool to adjust the spokes?

When filing the dropouts to fit the hubmotor, will this cause any problems if I wanted to put the original rim back on?

Also, are all hubmotors the same, like the HS3540, where you need to file out the dropouts? Would like to know if upgrading my hubmotor in the future would allow me to drop it right in.

 

[d8veh]

Your original axle was 10mm diameter, so the centre was 5mm from the top of the drop-out. Your motor axle will be 14mm from top to bottom and 10mm wide, so the centre of the axle is 7mm from the top, which is 2mm lower. Add the 1mm gap you now have at the top because of the different diameter and your axle is 3mm lower. Sometimes this no problem as long as the motor axle is all the way into the axle and you have extra torque arms to stop it turning. Without torque arms, it'll spin oout of the drop-outs as soon as you applly maximum torque. Also, if you have dimples in your drop-outs, they will not be central, which means that the washers/nuts don't fit flat, and when you tighten them, the force on the edge of the dropout breaks it off. These points are absolutely essential to fix with a front motor, but sometimes not a problem on a rear one, but it depends on the shape of the drop-out. Ubviously, you can''t rely on the anti-rotation washers to stop your axle from turning in the drop-out if it doesn't even fit. Look at this photo:

 

[dogman dan]

It could cause a problem later with a normal wheel back in.

It's part of why I often recomend that people don't take the best and most favorite pedal bike they ever owned, and put a motor on it. But mostly, I never want the pedal version of the bike back. Sell it later? Nobody wants stuff I'm done with. By then it's just parts.

You might be able to epoxy back some metal later. But this is what I'm saying here. Install it goofy, hit the throttle, crack or round out your frame. Now where's the value of that bike? Either way, installing the motor is like a virgin. She's not the same no matter what.

 

[EdwardNY]

I have noticed a problem. When I tighten one side of the axle it pulls the opposite side down a little. As soon as I loosen up the nut on that side it evens out.

The problem is I can tighten it down even on both sides as even one the other side is tight I can push the other side down easily, but the one side eventually must loosen up and fall back down. It isn't much and not that much of a problem if it falls down those few mm. However, that side does not have much clearance from the rear derailleur and the bolt hits it.

I wonder why it pulls the opposite side down when I tighten it.

I guess I can try and turn the axle around 180 degrees, but then the phase wires will not come out of the axle at that groove that is cut for them.

 

[d8veh]

I have noticed a problem. When I tighten one side of the axle it pulls the opposite side down a little. As soon as I loosen up the nut on that side it evens out.

The problem is I can tighten it down even on both sides as even one the other side is tight I can push the other side down easily, but the one side eventually must loosen up and fall back down. It isn't much and not that much of a problem if it falls down those few mm. However, that side does not have much clearance from the rear derailleur and the bolt hits it.

I wonder why it pulls the opposite side down when I tighten it.

I guess I can try and turn the axle around 180 degrees, but then the phase wires will not come out of the axle at that groove that is cut for them.

I think that just means that your drop-outs aren't parallel in the vertical direction. When you tighten each nut, the axle will go at right-angles to the plane of the drop-out.

Are you sure that washers and nuts fit in the dimple (if you have one) because that would also cause the problem. Do not leave it with a washer or nut on the edge of the dimple because damage will follow.

 

[miuan]

OK, I didn't do anything yet because I want to remove the annoying chain in the way.

So you live in NY, run a bike with a 3540 and no chain, and even think of an upgrade?

http://endless-sphere.com/forums/viewtopic.php?f=3&t=29292

 

[EdwardNY]

Ahh, they don't bother electric bikers in NY. Nothing that I have seen. The only electric bikes here are usually used by delivery men and usually look the same.

A custom built electric mountain bike are very rare in NY. I have yet to see one. I am always looking at bikes now to see if any are electric. Most people who see my bike and notice the motor are usually pretty curious, some will even ask me questions.

Yes my dropouts are not parallel in the vertical direction. I can see it by my own eye.

I am going to use a tiny shim to try and even it out.

 

[EdwardNY]

A tiny shim, just some very thin peices of aluminum folded was able to fix the problem. I drove it without the shim and the other axle moved out and jamed the derailleur with the axle bolt. Put the shim in and it didn't happen.

What surprised me was that before the shim I tightened both sides very tight, and even with the weight with me riding the back pushing the axle up into the dropouts, it still popped out on one side.

 

[dnmun]

no pictures, no torque arm, no C washer, alloy frame too?

 

[Ykick]

PM me if you want somebody with experience to try and take a look at what you're doing before it's too late. Also if you wish to see one of the "rare" mountain ebikes in NYC. I ride between Queens/Manhattan daily but outta town until next Tuesday.

Btw, axle flats are 10mm but the axle is most surely 14mm. If you don't have it fit properly it can and will walk right out of the dropouts under high torque conditions.

 

[EdwardNY]

Thanks Ykick, I would love to see another mountain ebike. I have yet to see any in NYC. I probably will never see one by chance either, I think there are only a few of them around really.

OK, the shim did not work and it moved out of the dropout a bit and the axle nut made contact with the derailleur.

I then put on some Nord Lock Washers on that side. I put two on that side, in between the torque arm I created. That seemed to finally fix the problem.
I drove 10 miles with it on and it didn't move a bit. Without the Nord Lock Washer it would slowly creep down towards the derailleur and lock the derailleur up.

I made two custom torque arms out of aluminum. These were temporary really, and I threw them together to get the bike rolling. They seem to be quite good. I will probably convert to steel when I increase my voltage above 48 volts. I have read reports of aluminum torque arms breaking. But it was easy to mill aluminum to create them.

 

[newman64]

can you show us some pics with the shims? I need to do a similar fix. I have bought a torque arm and c washers from ebikes.ca and I didn't want to do any filing just to keep the bike original
thanks

 

[newman64]

sorry, didn't see the last two posts, so forget about the shims pics.

If you have an alternate fix, can we have some pics please?

thanks

 

[dnmun]

i think this is gonna turn out bad. no pictures, so no way to know but axles doesn't stay in place, dropouts will not seat flush, aluminum TAs, newbie, filing, what & where? no pictures anywhere.

but that was where i got my first golden motor, from a newbie, it had twisted off in the forks on the first go.

 

[EdwardNY]

Here are some pictures of the torque arms. You can see the one side has two nord lock washers. One between the bike frame and the torque arm, the other between the torque arm and nut. This is so that it works properly. It will grip on the bike frame and also the torque arm and nut. These nord lock washers work great and my axle did not move out of the drop out. Normally it would move a very tiny amount before I put the nord lock washers on. Not sure why it slipped down. I know my dropouts are not exactly perpendicular to the axle so maybe that is why.

Torque arms are aluminum. They will be upgraded to steel when I up the voltage. They seem to hold fine as the aluminum is very thick, but who knows if it will break it like I have read reports on here about aluminum torque arms breaking.

I read another post where Wesnewell said the wire should be facing down from the axle because of water dripping down the wire into the motor? I guess I should reverse it?

Question: How tight should I tighten the hose clamp?

Chain side torque arm.

Here you can see the nord lock washer, torque arm, nord lock washer, bolt. You can also see the very small clearance from the torque arm to the derailleur

Other side clamping torque arm. Not the greatest design but I had very limted peices of aluminum to work with and milled them from what I had available that day

 

[dogman dan]

Guess somebody along the way shoulda mentioned that you make torque plates from steel. Might work fine anyway, for less than 1500w.

Something similar to the pinch design in steel should work well for a lot of torque. I run 72v 40 amps in a 9c motor on just one side pinched in steel. The other side just has a normal nut. No problems for two years.