Hi all....I am restoring a ZM20 1949. I have been trying to fit a rear wheel off a WM20 to the ZM20 frame but it looks like it's not going to fit. The ZM20 measures 7" across (measured with a tape) the rear while the specs for WM20 is 7" 13/32. The front of the ZM20 is different to the WM20 however the the rear frame looks the same. I know that the ZM20's had a different rear hub setup. Is it possible to make the WM20 wheel fit or should I give it up and try to find a 1949 wheel?

The rear frames and/or wheels are interchangeable....

Post war replacement frames for the WD bikes were the twin sidecar lugged post 48 type (66-4618) but were used in conjunction with the WD wheel....

When fitted to a post 48 machine, such as your ZB, the 'riveted' later hub was used in the same frame...

The rear sections of these frames are frequently bent and a discrepancy of just over 3/8" such as you have identified can frequently be found...

The WD frame is measuring up at the correct dimension...I would check the other one...

Rob Nortier from this forum makes and markets a tool for checking the frame I believe...Ian

email (option): ian@wright52.plus.com

I have a early WM20 frame which is fitted with a ZM20 riveted sprocket type rear wheel which is a direct fit,I would check your rear frame as they are easy to bend and yours could be squashed together at rear wheel mounts ! I also own a original 1950 ZM20 which I can measure for you if of any help if you need measurements.As far as I know both type of wheels should be a straight forward swap Dave T

Thanks for the reassuring information that the wd wheel should fit the frame. Perhaps you and Ian are correction that perhaps the frame is squeezed in, perhaps someone had tightened it up without the spacer. I will have another look at it.