Since this is a blog about electric bikes, you might be thinking that I’m going to talk about ‘torque-sensing’, but I’m not. I want to talk about ‘torque’ with respect to all the important fasteners on your ebike. You know, like to Allen-head bolts that hold your handle bar on so it keeps your front wheel going in the right direction and the handlebar doesn’t pop off when you least expect it – that would be a BAD DAY! So here goes:
Many modern ebikes have ‘bolt torque specs’ printed on the important parts, like this:
Or have a microscopic eye-chart located somewhere on the bike, like this:
So this begs the question “how would I know when I have the right torque?” when tightening a specific bolt, now that I know how much it should be. Well, I’m glad you asked. It turns out that some clever engineer designed a ‘torque wrench’ for just this purpose. And here’s the one I use daily. This is the Venzo 1/4 Inch Drive Click Torque Wrench Set from Amazon:
There are other sets available, but this one works for me. But let’s continue with some other useful information one should know about one’s ebike, starting with vocabulary.
Stem/Bar ‘Faceplate Bolts’ – 6N.m when 4mm Allen bolts are used, 10N.m for 5mm bolts
Stem/Bar ‘Top Cap Bolt’ – typically 8N.m
Stem/Bar ‘ Fork Tube Pinch Bolts’ – 6N.m when 4mm Allen bolts are used, 15N.m for 5mm bolts
Crank Arm Fixing Bolts – typically 35-40N.m
Thru-Axle (front) – 9-13.5N.m as specified
Rear Axle (for rear hub motors) – typically 35-40N.m
And this is just a few of the parts where proper torque is most important. Handlebars, pedals and wheels falling off does not make for a good day. When torquing other parts like chainring bolts, the derailleur hanger bolt (ebikes usually have only one rear derailleur), disc brake cable anchor bolts and disc bolts, saddle clamp bolts, shift/brake lever bolts, brake caliper bolts, and such I use the following chart as a guide. This provides a torque range to different size Allen bolts which is a good starting place. At the end of the day, too little torque can result in a loose part and too much torque can strip the threads on your expensive bike, so this is also bad!
The left column shows Allen bolt head size, and to the right, the approximate torque values. Use this only as a guideline should the respective parts on your ebike don’t happen to have torque values stamped on the part.
