Google has failed me or if anyone could measure one up for me that would be great.

bump

a pleading email to Thomson?

This kind of thing?

http://www.chainreactioncycles.com/Models.aspx?ModelID=14349

Sorry..A bolt for one of these little fella,s
http://www.chainreactioncycles.com/Models.aspx?ModelID=36479

It’ll be something standard like an M4 or more likely M5 bolt. If you struggle take the collar down to your local B&Q and see which bolt size fits. They might have the right length and head, or more likely not, but if you find that it’s an M5 for example then you can just Google ‘M5 30mm allen’ (or similar).

E.g. http://www.demon-tweeks.co.uk/Product.do?method=view&n=1591&g=240908&p=23013&c=215&utm_source=Google&utm_medium=Base&utm_campaign=Nuts%20Bolts%20&%20Washers

Or even better http://www.demon-tweeks.co.uk/motorsport/nuts-bolts-washers/pro-bolt-tapered-allen-head-stainless-steel-bolts

Ebay ‘thomson bolt’

Cheers for that gingerss .Thought some might know where i could get a genuine one before i went to my local engineering suppliers.
Thanks all…

no need for a genuine one. If you need to know the exact size and grade then give me a shout (and/or email) and I’ll dig mine out of my spares box and measure the bolt for you.

Mailed you Andy…Cheers.. 🙂

Hi Rob,

just dug it out and unfortunately it is a special bolt that has a rounded base to the head and one of the cupped washers fitted. It’s because it is a rotating barrel nut to stop bolt bending you get with other seat post clamps.

If you need to stick a normal bolt in then you need an M5 that is 24mm long total so about 18mm of thread left after the washer is fitted.

Cheers Andy…. 🙂