Radial lacing a hub motor.

[Brentis]

Gentlemen,
I currently run a Crystalyte H3540 in a 20" rim, because of the large diameter of the motor radial lacing is the only option.
A week ago I started to hear some "clinking" from the ass end of my bike, sure enough I had 4 very loose spokes.
I tightened them up with a spoke wrench, plucked at all the spokes looking for the same frequency "twang", & made sure the rim was still running true. I could glide hands free. All is good with the world.
Well that is until two days ago when I crashed hard. Second crash in as many weeks. This time I left about half a pound of skin on the road. Road rash sucks.
20 seconds before the crash I had done a sharp 90 degree turn @ speed that required me to drag a knee ( not exaggerating )
In that aggressive maneuver I felt what I assumed was the back end breaking free or shifting. I gathered (saved) that move,
but as I made my next turn the wheel was a wobbling mess. I couldn't save it this time & donated my skin to the asphalt.
Rode home in pain & bleeding @ a snails pace.
Today I worked up the courage (Road rash stopped oozing & scabbed over) for another ride. Hopped on made it 10 feet the wheel was wobbling like crazy & tire was flat. WTF.
30 of 36 spokes were loose. Very loose. I have tightened them up & got the wheel true'ish Not a hands free ride, but doesnt feel like its gonna chuck ya.

I guess my ?'s are,
Did I put so much stress on the wheel during my knee dragging corner that it moved the rim, loosening the spokes?
Can a couple of loose spokes lead to all spokes loosening in as little as 30kms?
WTF happened? what can I do to prevent this again?

If I come home bloody or bruised again soon, my woman & mother for that matter will harass me off of bikes.
Neither are happy with my self inflicted traumas, or the bike :lol:

Can I get some wisdom boys.

 

[rojitor]

I hope you are ok pal... Skin donations are not cool at all. Did you put some spoke prep or linseed oil on the spokes? That prevents loosening. And do you really know how to lace? The perfect tension that wheel needs etc? In my case i am not good at it so i took my bike to the store, professionals are always a safe bet.

 

[John in CR]

Get yourself a real rim, real spokes, and real tire if you're going to ride like that, not whimpy bike stuff. The 14" moto rims I have on motors the same diameter motor as yours aren't radial laced, and the tires are higher profile than most bike tires yet yield a slightly smaller than 20" wheel.

Put another way, the stuff you're riding on in terms of wheels are completely unregulated, and you're riding at a knee dragging motorcycle performance level. To me that makes more skin loss a guarantee without an overhaul from the spoke flanges outward.

 

[Kirk]

Lateral forces on a rim when you're out there knee dragging in the corners are way too high for a bike rim. The best DH rim you could buy won't put up with that. Atleast get a decent moped rim and one of the Perelli tires. Otherwise you'll be revisiting this subject.

 

[rollingreenhills]

I have seen this powerful motor on here:

http://www.leafbike.com/products/diy-bike-conversion-kit/20-inch-electric-hub-motor-kit/updated-20-inch-48v-1500w-rear-hub-motor-bike-conversion-kit-986.html

Which is radial laced.

I have a 500w 20" cargo bike bafang BPM 48v front wheel drive.

Can I radially lace the front wheel? At present it is one cross, but I can swap the rim to higher quality one if I switch to radial lacing.

The main reason is aesthetics more than anything TBH.

 

[teklektik]

You can instead go to "spoke pairs" which give the same strength as crossed lacing patterns. Easy drilling jig = small strip of metal, a hole, and a pin (epoxy bit of an old spoke or use a rolled pin from hardware store). Pin goes into existing hole, hold strip snug against the case/cover, shoot the new spoke hole, etc.

See thread by Justin: "A Much improved ebike spoke calculator"

 

[rollingreenhills]

Ah, OK.

I have a rim, which is the right size to use existing spokes, but radial rather than 1 cross.

I was hoping to re-use the spokes . . .

Does any body have a radially laced drive wheel that has worked reliably?

 

[ColinB]

Yep. I've got a Clyte 3548 in a 20" rim. I've had no problems, but it has needed maintenance.

- Radial spokes. Used on my heavy recumbent bike. Power is limited to 300-700 watts, speed average is 30km/hr. No knee dragging corners for me though. Drifting a recumbent is, ah, difficult, and I like my skin.

Pros:
- Done 14,000 km with this motor so far, no broken spokes. I've worn out one rim from the brakes, and replaced.
- It has been reliable, but with some maintenance needed.

Cons:
- Spokes had no thread locking compound when I got it. Some people don't like to, but I do. (So I did.)
- Added washer behind spoke head to better fit hole drilled in motor
- I listen for the spoke creak that indicates a loose spoke. And then I tighten that night. Before I had the spokes tighter, this happened frequently. (But you don't want the spokes too tight, or you could damage your rim.

Sounds like building up a motorcycle/scooter wheel is a good idea for you. Better tires, if anything. Maybe some protective clothing also?

Colin