What are the Correct Replacement Bolts for mounting your Bicycle Kickstands? 3/8″ – 16 TPI BSW Whitworth
Replacement Bolts for mounting your Kickstands are most likely a 16G 3/8″ Whitworth 55 deg Thread with a nominal metric diameter of 9.525mm, so close enough to M10 x 1.5mm but not quite, you’ll probably have trouble getting it to start although it may bit a little it’ll jam if you really try it or just take off the first thread.
It’s the kind of bolt you want to do up nice and tight, often util the mounting plate flexes under the bolt head, around 20 N.m / 14-15 lbf.ft Torque
The Correct Bolt
3/8″ 16G Whitworth 55 deg, 2″ Long, HEX Bolt (14mm Spanner, not 9/16″) with a Full Thread, preferably BZP Bright Zinc Plated, or Stainless Steel
So where do you get one of these? It’s a rather obsolete, and unobtainable part as bolts go, it’s a hard find. It’s the kind of thing you’ll find in a large selection pack of bolts, if you’re lucky you’ll have one in with your M10 bolts or close to hand.
What if I can’t find the correct bolt?
What’s best to do if you can’t find this rather obsolete bolt, what if I can’t find the correct bolt? Well given it’s size that it’s very easy to tap if you’ve got a bolt and tap set, I’d recommend that. It just so happens the hole size is a good fit for the ISO Metric M10 x 1.5mm Bolt Thread Tap being around 8.25mm ID it’s a fraction undersize, but use lots of cutting fluid and it’ll make a good thread. This doesn’t work if you’ve got a striped thread, or if ,maybe the hole on your Chainstay welded or brazed-on kickstand plate
There are of course taps & dies available if you’ve got a bolt with only a short section of thread, and you may find you can get away with a bolt 1/2″ shorter if you’ve got narrow gauge tubing as the 2″ tends to be a bit longer than required once fully installed, it does however make installation easier and slightly less fiddly having a 2″ bolt.
I’ve seen the topic covered on bike forums . net and after tapping a thread, then finding a couple of Full Thread 2″ x 3/8″ 16 BSW Bolts it made sense to make some sense of it all, as forums are full of small snippets and often lend off topic confusion to the matter. Old bikes are full of strange threads, and a lot of older threads are now hard to come by.
I hope you’ve found this useful, obviously there will be changes to the metric bolts already from many manufacturers and if you’re lucky you’ll never need to come across this article. I’ve just spent a bit of time writing up this article on the mundane topic of these bolts and if it gets enough hit’s and attention I’ll get in some bolts maybe, but it gives a good idea of how to work around the problem and should give enough info to explain everything you’ll give up looking for normally unless you wonder around with a bolt in your pocket or use thread gauges…