Wheel won't stay in fork. BL-36 kit, 20" wheel

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loumeth
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Wheel won't stay in fork. BL-36 kit, 20" wheel

1st time user of BL-36 kit on a 20" Miami Sun Trike. The motor wheel continues to spin out of the fork seat as soon as a you put a load on the trike. The tab on the non-rotate washer sits about 1/8" out of the fork slot. Does the slot have to be ground out so the non-rotate washer tab engages the slot? The wheel slot on this trike is a cantilevered affair and doesn't have a whole lot of stock left for deepening the wheel slot. I'm really stuck right now and hate to give up on it. Appreciate any input.
Lou

LinkOfHyrule
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

That's...odd, to say the least. Pics?

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loumeth
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

trike_2.jpgHere are some pics. Thanks for replying.

trike_1.jpgtrike_4.jpgtrike_5.jpgtrike_6.jpg

LinkOfHyrule
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

Hmm...as I suspected, it looks like the drop is too wide for the axle. The reason hub motor axles are made the way they are is because they put torque on it, completely unlike a normal bike hub. The nuts are incapable of preventing the axle from spinning by themselves, so the axle is made to press up against the sides of the drops and apply torque to them. Since yours are too wide, the torque is on the nuts and the whole axle spins.

You need a torque arm. AmpedBikes makes a good one. Hi-Power Cycles makes one, too, but it's not adjustable like the AmpedBikes one. Make sure they'll fit your axle, though.

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loumeth
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

Interesting. I measured the axle and slots and get .405" for the axle flats and .425" for the slot width. Is this .020 clearance too much play? Thanks for your help.

Lou

LinkOfHyrule
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

I dunno. But, other than there being something wrong with the axle nuts, I can't think of what else could be wrong.

The BD/BL-36's flats aren't really as prominent as they should be. :/

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whome
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

This looks very familiar. I had the same problem with my 26" BL-36. I ended up having to make some torque arms to keep it in place. Mine would spin and try to go down and out. To be fair though these new BL-36 controller throw a lot of torque on these new motors, and the vibration it generates when starting from a dead stop due to it being sensorless does not help any at all. Wish I had another solution for you other than to buy more stuff. Have Fun! This is only the beginning.

-Whome

dogman
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

A real torque arm will help a lot. The tabbed washer goes on the other side from the wires, and it will help some if the tab is bent in some. The best permanent solution would be to replace the forks. The ones for bmx bikes are the strongest, and usually have beefier dropouts than you have. Genererally on cheaper bikes the head tube is 1", and those forks won't cost that much.

I think the pressure of the nuts does have a lot to do with preventing axle rotation, but forks like yours don't have as much surface area for the nut and washer to bear down on. The washers and nuts need to really lay flat on the dropouts too,or the dropouts can spread as the nut is tightend. It does not look like that happened on yours, but if it did, the dropouts will be very slightly tapered in width. I have found the dropouts like you have can bend very easy. Torque arms are a great idea too, but I have not used them myself.

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loumeth
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

Hi,
i've ordered a torque arm from Amped Bikes. It looks pretty good. A question for all....... Have you ever heard of anyone taking a header using a motor kit with a good torque arm installed? The reason I ask is because we're in our 70s and not likely to tolerate a nosedive if the front wheel happens to spin out while in motion. I realize that nothing is certain but would be interested to hear of any experiences with this. Thanks.

Lou

LinkOfHyrule
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

Nope. I've heard of C'lyte ones failing, but not catastrophically.

Besides, since the highest torque the drops experience is when at low speed and drawing max amps, any failures are likely to happen at low speed.

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MattB
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Re: Wheel won't stay in fork. BL-36 kit, 20" wheel

A washer with a bent tab to go in that hole in your forks right above the axel. When I worked in a bike shop, they had washers that would extend with a little protrusion that stuck in that hole in your forks. This would keep the wheel from coming off with a Nylock Jam Nut or Locking Nut torqued onto the washer holding it's metal tab in that hole.

The torque arm sounds like a much more expensive solution to keep the motor from spinning off that slick surface with only a nut digging into the paint.

Matt

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