Doc_Wui

My other winter project is building a front wheel with electric hub motor for a 20"x3: fat tire e-bike. I have to use a motor from a regular ebike with a 135mm axle, which is the drop out size on the steel front fork. The motor is designed for a freewheel but I will not have one, so there's 2 cm of dead space on the axle. I will have to dish the wheel if I want to center it in the fork.

The Grin ebike spoke calculator lets me enter what I want for dishing, and also shows what it will look like in the bottom figure. If I want to center the wheel in the fork, the dishing looks a bit funky. .

I think I won't dish it at all. It will be disk brake, so no worry about rims. The result will be a bike with the front wheel track about 2 cm offset from the rear wheel. With 2-x3" tires, I do not think it will matter. And I don't ever ride no-hands. Any other tradeoffs for no dishing?

This will be my seventh wheel build, so I'm confident I can do it. The ebike issues are well in hand. Small motor, Steel fork.

dsbrantjr

I am not an expert but I do not see how you can make a wheel with the spokes on both sides pulling the same direction. I think that the -80 in the tension ratio entry is not possible, I think it would indicate a spoke which is under compression not tension. I think you need to center the hub somehow. Looking at the diagram it does not make sense.

jimincalif

Agreed. Spokes on each side have to oppose each other to hold the rim.

wesmamyke

Did you buy a rim yet? Surly, and maybe other fat rims have two sets of spoke holes so you can lace to just one side of the rim. I forget how much offset that gives you in general, but I think that's part of how the original Surly fat bike used 135mm hubs front and rear.

Doc_Wui

Yes, a fat bike front droput is 135mm and if I had a standard hub, the flanges would probably be 120 mm apart. This being a motor, the hub flanges are only 50mm. And in the no dish position, both flanges are right above the two rows of spoke holes, which are abour 40mm apart. so any dishing makes for the all the spokes leaning away from the far side.

We'll leave dish at zero.

AnkleWork

That wheel will not last long.

Dan Burkhart 

I have built numerous fat bike wheels, but I have never faced this scenario. I would try cross lacing in this situation, provided the hole would allow the nipples to swivel the opposite way enough. What I mean is lacing the right flange to the left row of nipple holes and vice versa. It would make the entire truing exercise counter intuitive,
Edit: Looking closer at the ERD and flange size, I'm pretty sure this would not work in this case due to the extreme angle the nipples would take on the left side. The earlier suggestion of a 64 hole rim (I have seen them in 26" but not sure about 24) and lacing both sides to the right might be the best solution.

WizardOfBoz

I guess I am technically what you call an expert, and everything "nonexpert*" dsbrantjr says is spot on.

You can't have both spoke sides angled towards the same size of the wheel. The software that gives a -80 tension is, shall we say, not bombproof to put it mildly. RH side spokes must angle to the left side of the wheel, and LH side spokes to the right. There are no exceptions for spoked wheels: spokes must be in tension.

If the hub setup is such that both flanges are on one side of the hub centerline, you have an unbuildable wheel.

*Don't believe him when he tells you he's not an expert! About 90% of the time I see a question and am going to answer it, I read down the list of posts and he's beaten me to it. And he's correct! And he's less wordy! Darn your eyes, dsbrantjr!

Doc_Wui

Aha, I figured it out. I measured wrong. I took the width of the freewheel as the dish, and din;t include any offset on the other side.

The last wheel I measured was three years ago and I did it correctly then, and since then I've made copies of that wheel two more times. Starting afresh, I screwed up on the wheel offset, I only need a few mm of dish.

Good to have your feedback! That would have been one heck of a wheel.
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