Spoke Length - Rear Mini-motor

[philf]

I see this talked around elsewhere on the forum, but no definitive answers.

I'm wondering what the standard spoke length shipped with the GM rear mini-motor is in a 26" double-walled rim?  I'm guessing form the dimensions I have available that it's going to be around 264mm with the standard 1X pattern and no dish.

Anyone know?

Cheers!

[philf]

Apologies for the double-post...

I thought this would be a slam-dunk.

Anybody?

I was hoping to get some spokes ordered BEFORE having to wait for the motor to arrive.  I can calculate the lengths, if Tom's drawing is the real deal, but there's nothing like hearing from someone who actually has one already...

[Perbear]

Here is a link to a nice site about building bicyle wheels. It has a lot of tips including calculating spoke lengths and how to measure them correctly. It should make it easy for you to double check the GM info:

http://www.sheldonbrown.com/wheelbuild.html#length
 
Good luck!

[Kevinator]

Did you ever find the answer for this?  I am waiting on a golden motor mini rear hub and would like to also get some spokes ready before the motor gets here.

[PEDAL IN POWER OUT]

I took a look at the rear mini motor spokes on a factory built wheel. The wheel is dished. It is very visible, because the offset is so large. It is a more radical dish than the GM factory 1 cm offset for the 'Pies for instance. That is hard to see when comparing the wheels side by side.
You should wait until you can put the motor in the dropouts, and see where the rim needs to be. Especially if spokes are that expensive.
Good Luck!

[GM Canada]

I have many assorted GM spoke sets. None of them labeled. Anyone know what lenght of Spoke goes in a rear hbs500w motor and a 700c rim?

Gary

[Kevinator]

My GM mini rear hub showed up, but it seems to wobble when it spins.  I sent GM an email asking for help with that issue. I don't want to spend a lot of money on spokes and a rim only to have it constantly rub the brake pads or prevent the wheel from staying true.  Its enough for me to notice on a 6" hub motor, so I would expect it to look worse when its laced to a 26" rim.

I'll be using a Velocity Synergy offset rim to help improve the spoke tension since the GM Mini is also offset.  Spokes will be Sapim 13/14 single butted.

Here's the measurements I took with my calipers.  They're approximate, not exact as it was difficult to get my calipers around the hub. 


Velocity Synergy offset rim
----------------
Effective Rim Diameter: 540mm


GM Mini rear hub
----------------
Flange Diameter: 133mm to the outsides of the spoke holes.  (~129mm to the centers of the spoke holes)
Center to left flange: 40mm
Center to right flange: 50mm


Using Sapim's spoke calculator, here's the lengths I will need for the GM mini rear hub: http://www.sapim.be/index.php?st=spokelength

Spoke length gear side: 246mm
Spoke length non-gear side:     247mm

Since I need to compensate for the offset rim, I will probably order all the spokes in a single length...like 246mm.