right, used spd's since they 1st came out.
used them on the road and on the mtb.
always take care fitting cleats, measure where they are and stick to the same position.
but over the last 2 months they make my knees and lower legs hurt.
to the extent that i have to get off the bike and walk/shake my legs till the pain goes.

help.

Try Crank Bros Candies or Egg beaters maybe?
There's more float & kinder to the knees.
YOu might be getting older. 😉

Saddle height,old age,combination of both ?

http://www.rivbike.com/article/clothing/the_shoes_ruse

Did you get new shoes recently?

I use several different shoes with the same SPD pedals and I've found I don't get on so well with types that have an raised "bulge" for one's instep built into the insole.

http://www.rivbike.com/article/clothing/the_shoes_ruse

What a load of $h!te.

Although pad pedal position and lack of float can induce knee pain but positioning, leg length, saddle position etc can affect it greatly 🙂

New shoes?

New bike?

Positions and stiffness can change. Or you got an injury somewhere else (even a little one) that is now being aggravated by the SPDs.

Loosen the float and see how you fair, and maybe try the multi release cleats. If that fails you may have to go Time…

Crank Brothers pedals sorted it out for me. Think the extra float they have makes a massive difference.

I do know a couple of guys that swear by Time pedals though too, never tried them myself. Again it's all about the float though.

Flat pedals would definitely sort you out, and you'd look the boy riding around on a road bike with some flatties on in a pair of Vans! 😉

Changing to time pedals from spd solved my knee problems too.

I'm sure you know this but sometimes just a reset of the cleats can really help. My natural foot position is way off straight (I found this by sitting with my legs dangling off a high chair) once I realised that my heels like to be more inboard than straight ahead and set my cleats up for that I've found my SPD's really comfortable. Might just be that over the years your foot position has moved a bit.

time here too, saves my old creaky/grinding knee a treat
spd's slaughter it

Time pedal's here everytime, but again I found the high collars on my MT90's caused me issues when I did the laces up tight on the collar section.

Time pedals here too, I've also had crank bros pedals in the past and found them similar in their ability to save my knees.
I've had shimano pedals in the past with same cleat position and shoe as with the Time/CB pedals and they did my knees in.
As above though, check they are set up right for how you pedal now.

I love that Rivendell article. Crocs and flats FTW. 🙂

Need to reset your ride position.

Obviously you haven't so go to LBS and get fitted.

Tony is it something to do with additional training, increased road riding etc. that you have been doing initially for the Keilder 100. If SPD's have been a constant feature over a number of years would it not be something that has changed recently that has started the aches and pains?

I had a bad knee for a stint and discovered one of my cleats had rotated slightly and was making my heel point in towards the chainstays.