Why TORX?

[michael franks]

I was just wondering why TORX bolts are used for disc rotors when Allen bolts are used extensively everywhere else on bikes. Is there some mechanical or engineering reason for it? Can Allen bolts also be used? Your thoughts please.

 

[ishaw]

Allen bolts are fine. I find torx bolts annoying and fiddly in comparison to Allen bolts. Not sure why they are used though, to sell mor tools?

 

[scant]

disc rotor bolts need shallow depth heads for clearance between the rotor & the fork leg. torx heads are harder to round/strip the internal splines, compared to allen head bolts, of a similiar low depth.

its an old mechanic hack/bodge that if an allen head bolt has internally rounded, you can often hammer a torx head into the damaged allen head & loosen it with the torx.

if anything torx will become more common than allen head. campagnolo use them a lot already on the road groupsets for brake calipers, stis etc & I've noticed torx starting to appear on stems too.

 

[T'boo Ted]

my new bike, everything is Torx, drives me crazy, especially when they aren't 25's (as the only Torx I had were on multi tools, and 25. SO stem, seatclap, disc bolts, grip lock ons, everything that wasn't shimano was torx, and I hate them, they are jsut more fiddly.

3T have made everything Torx because it is apperntly better and you can never ever strip a Torx... yeah, I think I can strip one.

 

[tufty]

Torx beats allen in almost all use cases. And I only say "almost" because, despite not knowing of one, it's possible there is a case where allen beats torx.

The best way to get a rounded allen bolt out, by the way, is this:

You will need:

• One allen driver bit (electric screwdriver type) of the correct size, and a tool for turning thereof.
• One nail punch.
• One hammer. It wouldn't be a job without a hammer.

Procedure:

• Put the driver bit in the now-rounded allen bolt head.
• Use the hammer and punch to re-form the allen bolt around the driver bit.
• Hit the bit with your hammer, a good hard hit directly dow the axis of the bolt, this should shock the threads of the bolt enough to make make them work.
• Use driver / electric driver to take the bolt out in the usual way.

I haven't come across a bolt I couldn't extract this way yet.

 

[T'boo Ted]

Can't say in 24 years of using allen bots on bikes that I've ever rounded one or needed to extract it with anything but an allen key... Only had shoe cleas bolts fill up with mud-> concrete but no real issue getting them undone.

 

[scant]

Can't say in 24 years of using allen bots on bikes that I've ever rounded one or needed to extract it with anything but an allen key... .

on my own bikes that I look after, I havent either. on bikes I've bought 2nd hand & have been neglected, I've had to use torx a lot.

 

[Thias]

It was the same discussion when allen bolts were introduced to replace the hexagon bolts. No one had the tools so everybody was shouting.
Torx is the better system. In most cases. The problem is lack of tools. If I had all the allen bolts swapped for torx, I would have to buy a new multitool (with torx). Do these even exist?

 

[mattr]

Yes, i've got a couple of torx multitools.

But none of my bikes use torx everywhere. They are all a mix.

And as above, torx are a better solution than hex allen keys. You can get the same torque through a smaller, lighter bolt, or use a lighter material.
Much the same way as 12 point is a *better* system than standard hex bolts.


For a given value of better.

 

[scant]

If I had all the allen bolts swapped for torx, I would have to buy a new multitool (with torx). Do these even exist?

£5 at screwfix for a cheap-ish multi-tool that works ok.