Trek 800 Dropout Width

Do people ever have too modify dropout widths to install hub motors? I'm looking at putting a Bafang SWXH on a Trek 800. The drawing for motor says the flat-flat dimension is 10 mm +0.0/-0.1. I'm measuring the width of the dropouts to be roughly 9.5 mm with calipers. I wiped both sides to make sure there wasn't grit or anything in the dropout before measuring it. I checked a old specialized frame and it was just over 10 mm. Any thoughts?

Looking into it.

File it .5mm wider, and if your motor has the 14 mm axle, 2 mm deeper will center the axle where it's supposed to be. (14mm the round side, 10mm the flats) It might be 12mm round side, if so, file only 1mm deeper.

The typical QR axle is 9.5mm but usually the drops are cut 10mm, then paint adds up to .5mm. But actually cut to 9.5mm is possible.

Don't file anything till you see if the axle fits. The tighter the better. If it fits file the depth of the dropouts a Dogman says.
If need to widen the with, do as little as possible.

Dan

Well, yeah,, If his axle is really 9.8mm, then file to exactly 9.8mm.

Don't file to 11 mm, to make it an easy fit! Make it tight.

Thanks for the info. I ended up not needing to file anything, not width anyway. It was a fairly snug fit, but it fit. Although as you pointed out, I may need to file it a little deeper so that the center of the axle sits where it was intended to on the frame.

A 10mm axle won't go into 9.5mm slot. Therefore, you will need to file. Many dropouts are 10mm, so filing is not necessary, but those that use QR skewers are often narrower.