whats a good time/age for kids to start on spds? my son is driving me mad for some but to date thankfully not been able to find any shoes to fit him

Never!

My son uses them on the road. He has coped very well. But I wouldn't entertain them for him off road! He is 9.

I had always considered that it was something best left until adolesence due to a risk of damage to the knees but I have since learned that the kids down at the local track league use them at your lads age. What size is he?

I had toestraps/clips by the age of 11 IIRC.
I have knee problems now. I'm not sure if they're related.

why the hell not?

if he wants them, let him have them? i dont see how its any harder than you using them?

in FACT

its proven that kids are more resiliant to tumbles, they are designed that way (if yours isnt, i hope you kept the reciept)

he is lighter, and hasnt got as far to fall when he comes off ANYWAY so probably wont injure himself.

riding spds or not isnt going to change the fact that mtbers come off, sometimes in a big way.

whats the issue?

if he tries it and doesnt like it, youve gained a pair of pedals, and only lost the cost of the shoes…..

My 12 year old uses them off road, on road and for cross racing. However I do make sure to keep the tension wound back and they are shimano spd's so they do have float.

My son has been using them for the last year. He is 9 1/2 now. He races cross at under 10's and is a regular at the local go ride bike club. They are natural to him now, on and off road and just like anyone it took a little while to get used to them. They really help with foot positioning on the pedal as we see so many kids peddaling with their heals. Set the pedals on the loosest setting and I gave him an old pair of cleats and a worn pair of pedals as new ones are very stiff. The hardest thing was finding shoes small enough 36 was the smallest which were fine for him now looking for another pair.

British cycling (& possibly UCI)ban them for under 13's in BMX racing. Does not answer the question but thought I would share.