Allen Bolts V Cross Head screws

[irc]

I've just replaced the low adjusting screw in my front derailler with a longer one. The one I had was an Allen bolt rather than the fitted cross head bold. Which made me wonder why derailler adjusting screws and V brake adjusters are just about the only place where Allen bolts are not used as standard.

Allen bolts have the advantages for me that eliminating non allen bolts means one less tool to carry and for the mechanically challenged, like me, it is obvious when you are using the correct size tool so the don't get damaged. So why not Allen bolts everywhere?

[BV1961]

Good question.....I would guess its because an Allen head is longer than a cross head and will stick out if there in not enough material in the derailler or brake body to accommodate a counter bore.......but that could be accommodated in the design...so yeah, good point.

[profpointy]

I sawpped over all my cross head adjusters for high quality stainless allen screws. Much easier to adjust and superior fasteners as the originals where made of the special cheese-derived material used for japanese cross-head screws

[ambodach]

Where did you get the Allen bolts please?

[Vantage]

Screwfix stock pretty much every size you could ever need.

[nirakaro]

Or for huge selection, good prices, small quantities look on ebay - e.g.seller called massiveattack007

[CREPELLO]

Where did you get the Allen bolts please?

Best selection I've found is here... http://www.gwr-fasteners.co.uk/

[Mick F]

Most towns have a nut and bolt shop, you don't need Screwfix etc.
Look in Yellow Pages or Google it.
By calling in at a shop, you can see the items in the flesh and you can buy only one or two for pennies ........... and no delivery charge.

This one is our's in Plymouth.
http://www.expressfixing.co.uk/
Good friendly service across an nice old-fashioned counter.

[yakdiver]

Where did you get the Allen bolts please?

I've just bought some stainless ones from ebay 4mm 5mm and 6mm

[RonK]

To avoid blank looks from the counter staff, ask for cap screws.

[TrevA]

Most towns have a nut and bolt shop, you don't need Screwfix etc.

Not anymore they don't. We used to have one called Hannams but it closed years ago. Most go to Wilko's and B&Q for their nuts and bolts now.

[Mick F]

Are you sure?
I'd be surprised it it were true.

[531colin]

I've just replaced the low adjusting screw in my front derailler with a longer one. The one I had was an Allen bolt rather than the fitted cross head bold. Which made me wonder why derailler adjusting screws and V brake adjusters are just about the only place where Allen bolts are not used as standard.

Allen bolts have the advantages for me that eliminating non allen bolts means one less tool to carry and for the mechanically challenged, like me, it is obvious when you are using the correct size tool so the don't get damaged. So why not Allen bolts everywhere?

Good question.....I would guess its because an Allen head is longer than a cross head and will stick out if there in not enough material in the derailler or brake body to accommodate a counter bore.......but that could be accommodated in the design...so yeah, good point.

I think its just penny-pinching by the manufacturers.
But they all do it, AFAIK.....when one breaks ranks, will the rest follow?

I don't think the argument about the size of the cap head holds water.....the bolts don't have to handle any force to speak of, and if you want bolts by the shipping load you can get "specials".....for example, you could have an M5 limit stop screw tor a mech. with the size head normally used for an M3.

An M5 cap screw normally takes a 4mm Allen key http://www.westfieldfasteners.co.uk/A2_ScrewBolt_SHCap_M5.html
however, put a button flange head on it, and its 3mm Allen key http://www.westfieldfasteners.co.uk/A2_ScrewBolt_SHBtnFlg_M5.html

Shimano cantilever and Vee brake centering bolts used to be socket head grub screws, back in the day.....2.5mm allen key on those..http://www.westfieldfasteners.co.uk/A2_ScrewBolt_GrubFlat_M5.html.....would be fine for limit screws, I think.

[[XAP]Bob]

Are you sure?
I'd be surprised it it were true.

We had one up until a few years ago - I couldn't tell you if it is still open since it's not on my commute any more.
We've got builders merchants etc - but they're not nearly as helpful.

[Brucey]

Screwfix stock pretty much every size you could ever need.

except they don't.... (No M3 stainless....etc)
BTW some mechs used to be fitted with screws that had both an allen key socket and a plain slot.

If they seize up (not that uncommon in some designs) you need a mighty force to shift them and the allen key just won't cut it. Because the clearance between the key and the socket doesn't get progressively smaller as the key size reduces, maximum allen key torques do not reduce pro-rata with key size; it isn't even as good as that. Cheaply made small allen keys and matching bolts might as well be round if you lean on them at all....

cheers