OK, so I’ve not ridden rigid forks since about 1995 (yes, I was late to front suspension) but I’m looking to put an old Chameleon frame back together as a single speed to go down the pump track and along the old railway line with the boy. But, I’d also like to use it occasionally in the woods/FoD when I’m feeling really masochistic. So, will I hate it and what sort of forks should I be looking at for ‘good value for money’…bearing in mind I may hate it? Also, am I right in thinking 450mm c to a is about right for 100mm suspension corrected? And why are only uber heavy jump bike forks available with anything resembling a secure axle system (as in 15mm or 20mm)?

A pair of carbons of the bay of fleas and you’ll be fine.
QR skewers are ok, what are you planning to do that requires big axles?

I’d look at carboncycles.cc and buy whichever suits. 440mm is a more common size a-c than 450, though.

Salsa CroMoto come with Maxle option, not sure what the A2C is on them though.

Rigids feel stiffer than suss forks anyway IMO, most of the flex in suss forks is due to the fact that they’re tubes that slide up and down inside each other, so they need bracing and through axles to stiffen em up..

The big axle thing just makes it easier in the garage, rather than swapping wheels – that was all.

440’s will be fine and I can easily fit a 29 front wheel in mine which I find better for riding in the summer when the grounds rock hard. I revert to a 26 in the winter but only because I’ve got a dynamo hub built into a 26 wheel. I didn’t get into any form of suspension until 98 but find rigid far better now than when I began in 86. Carbon forks and bars and wider tyres have improved things considerably and disks means my hands hurt less than when I was trying to stop with cantilevers. In fact so great has been the improvement that I don’t even need my Flexstem anymore!

The maxle option only comes on the 29er/ 470mm length Cromotos. (plus they are 1.2 metric shedloads more expensive)

I’ve got the 425 cromotos on my c.80mm corrected bike and they’re bob-on. Bike feels really good. 440/445 should be great for a 100mm corrected frame. If you’re looking at the A2C of your fork and going straight from that, remember that when you’re Just Riding Along, they’ll be riding at 25-30mm less than that as they’ll be sagging under your weight.