Spokes breaking on drive wheel and spoke lacing patterns

[Halichopter]

I have a Magnum e-bike conversion kit installed on a tandem bike. I understand that a tandem has twice the weight load per wheel and the spokes get more load than anticipated on a single bike.

The additional torque from the motor and the motor + battery weight add even more stress.

The wheel has a 1-cross lacing pattern. I understand 2-cross and 3-cross handle torque better. I took the wheel to a bike shop and they said the wheel cannot be laced with anything but the 1-cross because of the large hub.

I called Magnum bikes and they thought that the lacing could be changed to 2-cross or 3-cross but it was just shop talk and I couldn't get any details from Magnum. They suggested I post on this forum.

I break a spoke about every 40 miles and have gotten good at field replacing them. But I'd rather not.

Questions:

1. Has anyone heard of lacing other than 1-cross for an e-bike drive wheel?
2. Are there a super strong (titanium) spokes to use instead of the standard ones?

Thanks in advance for any help.

Hal

 

[harryS]

If you plan to relace the wheel, the spoke experts on the endless sphere forum say you will do better with thinner spokes, like the Saphim Strong. They're 13G at the elbow and narrow down to 14G at the rim, and provide better tension than 12G or 13G spokes.

The guys at grin ebikes say a 2X cross is difficult to pull off with most bigger hub motors and there's no benefit. You can plug in your motor dimensions here.

Online Spoke Calculator for Hubmotors and Ebikes

Our handy spoke length calculator allows for easy calculation of spoke length for custom builds - and is the only one of its kind to include paired spoke holes in the flange as is common with many large diameter hub motors. It also creates an automatic side view drawing of the laced wheel and...

www.ebikes.ca

 

[Halichopter]

Thanks. To use thinner spokes, does the whole wheel (plus motor) need replacing?

 

[harryS]

If your rim is in good shape, but drilled for 12G spoke nipples, they sell washers, but why not buy a stronger rim.

While they put 12G spokes in most motor/wheel combos, the motor should take the 13G elbow. I've spoked several motors with 13G elbows.

I've not broken any spokes, but don't believe that I put a lot of stress on my wheels.