Dan, you must be kidding surely ??
'S'truth, Pete. I eventually tried no fewer than
six different Shimano SPD pedal models, and it wasn't until I tried the T400/T700 with the tension dialed to minimum combined with their included multi-release cleats that the knee pain eased and eventually subsided. I never had it in 35 years with my Dettos and Pavarin cleats (up and back to release), but I sure did have it with the other SPD pedals that had stronger springs and required a heel-out lateral release, at least when used with my new Shimano MO88 shoes. I even had it when the tension was dialed to minimum and I used multi-release cleats.
The main component was the heel-out release, but the spring tension of the SPD pedals was a huge factor as well,
even with the multi-release SPD cleats. I've got to tell you, it
really hurt inside my knees, a deep bone-ache and
bad. I gave up entirely on them for a bit, then sat on the bike without riding and tried releasing from the pedals and after about three tries -- BAM! -- massive knee pain again; that seems to be what caused it. I gave up riding entirely for about three weeks, during which time my knees felt wobbly and sore when walking and getting out of a chair, about the way they did after the long-ago car accident, and it scared me plenty.
After resting from riding completely and returning to the T400s with the same cleat position as before, again no problem! As soon as I tried another of the other SPDs, the pain returned immediately, so I have to say that in my case and for my knees, I just couldn't stand to use "normal" SPDs even with minimum tension and MR cleats, and had problems until I discovered the T400/T700 pedals
also with the tension dialed to minimum on both sides of both pedals and MR cleats. Spring tension that is acceptable or minimal for others sure doesn't seem to work for me.
I'd never heard of others similarly affected till I read the product reviews for Shimano's SPD pedals on Amazon and various vendors' sites, the comments written by people with prior knee injuries or knee surgery or knee replacements reported finding relief in the T400/T700 line with those pedals' greatly reduced engagement/release tension. I guess I must fall into that same category, 'cos I sure had problems with standard SPDs that resolved entirely with the T400/T700 pedals (identical except for a few grams, cage shape, and an XT-level bearing/spindle assembly on the T700).
There's a good in-depth review of the T400s on BNA here:
http://www.bicycles.net.au/2013/03/shimano-click-r-commuter-cycling-pedals/The downsides? They look dumb to other riders (who won't mind telling you so) and they are *heavy*, though not as bad as one might think compared to others like the popular M324. REI actually weighs a range of samples then averages the results, so here's how the T-pedals stack up against other Shimano SPD pedals they carry:
315g - A520
346g - M540
380g - M520
383g - A530
398g - XTR M985
457g - T700472g - M424
507g - T400530g - M324
By the way, a new version is available with the T400/T700 pop-up, low-tension cleat on one side and a plain platform on the other and is called the Shimano Click'R PD-T420. See:
http://www.chainreactioncycles.com/us/en/shimano-pd-t420-click-r-pedal/rp-prod108681 They seem to be very popular among German bike-trekkers.
Best,
Dan. (...who thinks T400/T700 pedals aren't for everyone but sure worked for him when others hurt his knees)