For some strange reason one of the three Gamut chain devices I own doesn't use a 5mm allen key on the lower jockey wheel- its slightly smaller suggesting its an imperial bolt.

Anyone help with what size it'll be so I can get the right size allen key? Not a 4mm so somewhere inbetween..

4.5mm will probably do it then

Like your logic there- but don't have one of those and I'm gussing its more likely to be an imperial size..

3/16ths?

Yup that seems about right, cheers.

If anyone has a spare let me know- nothing else uses that size for me.

My profile imperial cranks have an imperial sized allen key bolt to hold them on. I dont know what size it is in imperial terms, but a 5.5mm allen key works a treat.

r3g are you still after a 3/16" Allen key ?

Please 🙂

r3g mail me your address details and I will post it Sat. (12 hr days tomorrow :cry:)