What threads for Dawes Horizon braze-ons?

[ed_b]

I was going to go for a ride but it's raining so I thought I'd tackle the snagging list.

Does anyone know what threads are tapped into the frame on a Dawes Horizon? The bolts at the mudguard stays (5mm Allen, end of fork) seem like they might be M6 - can anyone confirm? But oddly the low-rider bolts (4mm Allen, half way up the fork) seem to be different. Am I right? Bit annoying if so, can't see why you wouldn't standardise across the bike.

Other minor prob is it seems I've cross-threaded one of the ?M6 holes - any tips for retapping without an expensive tap, very welcome. Thanks!

Ed

[tooley92]

They should all be M5 unless anyone has drilled them out and tapped them for M6.

[fatboy]

What year Dawes Horizon are you talking about? They have made them for years! My 2004 one seems to have the same thread for everything (racks, low-riders, mudguards etc) apart from mudguard bridges. What size they are I never can tell. But I think that it's M5 (but don't quote me on it!).

[meic]

A cowboy method is to just put a bolt with a new clean thread through the existing hole.
If you have a few bolts then go part way, remove the bolt, bin it and continue with a new bolt.

Also do it from the other side of the hole so the bolt hopefully starts on some good thread.

This is more than likely to damage your threads irreparably, if it doesnt fix them and then you can put a bolt through and fix a nut on the end of it.

[ed_b]

Thanks for these. Horizon is 2010 model.

Thinking if they really are all M5, gonna buy me some extra bolts with 5mm Allen head, and swap out the ones with the 4mm head. Why would you put different heads in difft places?!

Liking the cowboy suggestion, and never thought of going from the other side. Good tip.

[tooley92]

I would change the ones that take a 5mm allen key to ones that take a 4mm allen key, it's far too easy to crank up the bolts too tightly and run the risk of stripping them with a 5mm key.

[531colin]

To make a "chasing tap" ie. a tap good enough to clean up a thread, make a hacksaw/file cut along the length of the bolt.
Screw it in a bit at a time, don't force it and shear it off. ....back it out often and remove the debris which collects in the cuts you have made.

[meic]

I forgot to mention,

dont do it dry, if you have no cutting compound then use some oil or grease at least.

[BeeKeeper]

If you want to do a proper repair then a local firm might be able to put a helicoil in for you but I guess it will cost a few pounds but you can also buy an M5 helicoil repair kit on whatsit bay for less than a tenner. Helicoils are ideal for stripped threads in aluminium but they work in steel as well.

[Trigger]

Why would you put different heads in difft places?!

So that numpties can't crank up bolts, designed for less force, with big allen keys.

[ed_b]

Well this numptie always uses a 10cm Allen key, so he might manage to strip the threads even with a 4mm head...

Thanks v. much for all the advice. I'm going with the DIY chaser tap, and I'll let you know how I get on.