I've tried off and on for many years to get used to clipless pedals. Doing better, but right now, after a few miles, i get a pain in my left knee, under the knee cap, a bit to the inside of my leg.
What do a need to adjust?

Which pedals, cleats and shoes are you using?

Do you have any aftermarket in-soles either custom ones or drop in replacements, e.g., Conformable, Superfeet, etc. ?

Has your saddle height and set back been checked either against the "standard" formulas (one size fits none) or by a good LBS?

What is your average cadence when cycling, i.e., do you spin at >90rpm or grind at <80rpm ?

Are you riding a geared bike or a fixie? If it's a fixie, do you do a lot of pedal braking and skid stops?

I've had them so long, not sure on the brand. I'll take a photo of them tomorrow and post it, so you can see what they are.
I think the shoes are more of a mountain biking shoe. I have a very wide foot and had trouble finding a shoe that was comfortable.
I think my saddle height is ok, and the front/back position ok, I've read how to do that, and believe it's were it needs to be. My knee never hurts when riding with the platform pedals.
Not sure on cadence, my odometer does not measure that.
I have a 21 speed mountain bike and an older 18 speed road bike. I live in a part of Arkansas where there are plenty of hills, not really mountains, just hills.

Click on "Search The Forums" near the top of the page and search for "knee pain" and read tons of info on the subject. And if you do that I guarantee your pain will go away because there is so much there to read you will no longer have time to ride your bike.

You could try pedals with free float, such as Speedplay pedals.

Assuming your bike computer shows speed, here's how I figured my cadence out. Go to the website below and enter your chainring and cog info and print it out. Go for a ride and get in the gear that you normally cruise in and note your speed on the computer. Look up that gear ratio on the paper you printed out and find the speed you were going and that'll tell you your cadence. https://www.hostelshoppe.com/tech_gearcalc.php

Adjust your cleat toward your instep and toward the toes, moving your foot out and back.

Or just get the cleats you have adjusted properly for you. This can take a good bit of trial and error.

Thanks for the reply

+1 Lol

I too have knee pains, but I found something that has helped immensely. My foot doctor even thought this was a good idea. Part of the problem may be the angle that your leg is put in using the clipless pedals. I use free-float Shimano SPD-SL road pedals so that helpes lower the torque you may put on your knee. I have started using the "Cleat Wedge." Made by the Kool Kover company, you can use these thin plastic wedges between your shoe and cleat. They can help to angle your foot so that the alignment between your foot and lower leg (through the ankle) is straighter. This in turn helped lower my knee pains dramatically. When you are using your platform pedals, my guess is that you're actually angling your foot a bit without thinking too much of it. These wedges are not expensive and have been a knee-saver for me. Here's the link to their site: https://www.koolkovers.us/thewedge.html
Good luck, I hope this helps!!

-CyclingCowboy