I need some longer cleat bolts for my SPDs (don't ask). If I order metric M5 x 20 countersunk socket caps they'll do the job but I think they come to suit a 3mm hex key rather than the Shimano 4mm. Not a major issue going in but could be fun coming out 12 months down the line. There's also a Torx option but I'm not sure what size bit.

So…

Anyone know where I could find 20mm long bolts (overall length) with 4mm hex, or
what size the M5 Torx bit would be for a countersunk head, or
have a worthwhile opinion on whether a small Torx or 3mm might be better in the long run?

Cheers.

I'd ebay (m5 allen bolts countersunk), get a pack of 20 for about £3 copaslip them in and remember to change them when the heads started lookin iffy. (or just drill and throw away at that price)

You could just 'Dremmel' a slot in them & use a large flat bladed screwdriver to take them out when required

These and plenty of copper slip and you'll be fine.

I've gotta ask though, why?

Okay, I'll tell you but you have to promise not to take the p155.

My podiatrist told me I have a left leg that's 6mm shorter than the right. This is evenly split between the upper and lower leg. To compensate for this on the bike, I need to move the right foot forward 1.5~2mm and raise the left by the same amount. I've done this by cutting a spacer from an old Ikea chopping board.

To make matters worse, I also have a consideable forfoot varus angle on both feet. So, I mate two more spacers and then filed them down to make a wedge. All this looks like it should work quite well except for the fact that the cleat bolts don't reach the plates anymore! Hence the need for something longer. I've got a set og lemond wedges for the fine tuning but I need a good tilt for a starting point. I know a few mils and a few degrees don't sound like much but it's been messing me up for years it seems. Told you not to ask!

How on earth will you be able to walk off the bike? Won't the cleat sit proud of the sole?

yeah, they will a bit but not as bad as a pair of road shoes, only 1/8 inch at a guess. It's a small trade off for the benefit on the bike.

Hope your experiment works, I know moving my cleats back a few mm's seemed to cut incidence of leg cramp on longer rides.

Cheers, I hope it does as well. I asked my podiatrist about doing something professional for my cycling but he said I should try the above and adjust things on a suck it and see basis. Seems cycling is less precise that running and walking in terms of foot mechanics.