Bit of a odd request here! Building up a couple of new bikes with Pro 4 SS/Trials hubs on them. Rear spacing is 135 x 10, using chunky M10 steel bolts as axles.My question is where can I find some M10 bolts in lengths 35mm & 40mm, in grade 10.9 or 12.9 steel, button or socket headed, with an unthreaded section beneath the head?

I’ve found in the past with rear Pro 2s especially on aluminium dropouts, the M10 bolts with full thread all the way up to the head gradually chew up material around the slot, enlargening the hole. Pro Bolt make the ideal shape I’m looking for, but only in Ti:

Sweet, Sweet Ti
vs

How much thread/non-thread do you need?

The problem you’re going to have is that the Hope axle is threaded right up to the end (unless the design has changed and the thread starts deeper inside now), so you’ll either have bolts that bottom out on the unthreaded bit before being sufficiently tight, or if you use a bolt with less unthreaded section (or pack washers on the outside) you’ll still have threads in the dropout to chew it up*.

That’s why the CK fun bolts threaded bit is bigger than the 10mm unthreaded bit to avoid this issue.

*If a hub is sufficiently bolted in the bolts shouldn’t actually take any vertical (ie: into the dropout) load so shouldn’t chew it up, the interface between the end of the axle and the frame should be enough, but the real world is often not ideal so you do get the chewing you describe, especially with frequent fitting/removal.

Nowhere near as pretty:

https://www.accu.co.uk/en/cap-head-screws/16140-SSC-M10-35-12-9

https://www.accu.co.uk/en/cap-head-screws/16141-SSC-M10-40-12-9

(And special order, too :/ )

What thread? I’ve got some parallel head M10 x 1.25 x 55 titanium socket cap bolts here with 27mm of plain shank. They can be cut to size and they’re a butt load cheaper at £2.50 each than Pro Bolt 😆

Could you not use some ‘liquid metal’ to fill out the threads on the section that fits in your dropouts?

Best I could come up with: http://www.ebay.co.uk/itm/M10-10mm-A2-Stainless-Steel-Hexagon-Socket-Button-Head-Bolts-Socket-Screws-/181056957110?var=&hash=item6fcec06929

I use their chunky as **** socket head ones as I don’t like button heads. Have not experienced the chewing-up issue you mention – yet…

Their only part-thread ones are hex heads, which would be an interesting look 😆

Pitch is 1.5 for sure. The ones tillydog’s post are pretty much exactly what I was looking for :D. Awesome to see they’re available in black 🙂 I prefer the rusted look compared to shiny zinc plated.

amedias you make a good point. That’s something I’ve considered too, as different frames’ dropout thickness will have a direct impact on how compatible these partially threaded bolts will be. I’m going to give tillydog’s suggestion a shot and see how the 35 and 40mms fare. I expect it’ll be fine, as it’s always possible to tweak it with different thickness outside washers. I have some Halo M10 alloy serrated washers which could replace the Hope ones.

Also considering the Hadley 10 x 135mm bolt thru-axle for a different frame.
Hadley Thru-Axle
It’s a solid 7075 rod running all the way through vs a pair of steel studs. Which is stronger?

Assume this bike is being specced for a heavy brute that’ll give it a life similar to that of a skateboard 🙂

Do they *need* to be high tensile grade? There are some stainless ones on the same site IIRC

Aeris rocker bolts sound perfect for the job. High grade stainless and custom milled so a nice finish. I could let you have a pair I reckon. I’m back at hq tomorrow. Message me on ben@birdmtb.co.uk

amedias you make a good point. That’s something I’ve considered too, as different frames’ dropout thickness will have a direct impact on how compatible these partially threaded bolts will be. I’m going to give tillydog’s suggestion a shot and see how the 35 and 40mms fare.

The other slightly more drastic option, would be to drill out the first 5-10mm or so of the threads in the end of the axle, as long as the thread goes deep enough into the rest of the axle that would give you a bit of leeway.

Take that recommendation with appropriate caveats though as I don’t have a current model SS hub in front of me to check the axle dimensions/thread depth etc.

Bolts usually have 27-30mm of thread, so any bolt up to 30mm will be fully threaded. Anything longer than that will have 30mm of thread and the rest will be plain shank, so an M10 x 1.5 x 35 bolt will have 27-30m of thread and 5-8mm of plain shank, an M10 x 1.5 x 40 will have 27-30mm of thread and 10-13mm of plain shank so you could buy what you need and trim the excess thread off. Set screws are fully threaded.

The length of a bolt is measured from the underside of the head to the end of the thread, unless it’s countersunk, in which case the height of the head is included in the overall length.

You may or may not have known this already but it might help some others if it’s picked up in a search! 😀

I much prefer the White Industries sleeved washer solution, at the expense of a smaller bolt.