I'm going to REI to buy my first pair of clipless pedals. Do I get the M520 or M540 Pedals? Please decide for me...

Yes.

This is sort of another smart*** answer, but I think Crank Brothers Eggbeater pedals are superior to spd pedals. Why are you set on Shimano spd's?

I bought the M540's because I liked the color. I've subsequently seen diagrams showing that the pedals are essentially identical, so it's a good thing I didn't buy the more expensive ones for performance reasons! BTW, I really like mine for commuting even though I'm on a road bike. They are 2 sided so no looking before you clip and the clips are recessed so wen I get to work I can walk around with click-clacking.

I love my 520's.

I agree drbenjamin I have have the 540's and they work good. Just make sure you have the tension adjusted so that you feel comfortable clipping in an out of each pedal. My left is set to a higher tension than my right since I usually unclip my right foot and then my left but when I clip I clip my left first. So keep in mind having each one tensioned differently may be helpful.

Not always. You need to rebuild CB pedals a lot often than SPDs. SPDs are much more reliable too.

Do any of the CB pedals have a way to adjust the tension on the springs at all? One of my bikes came with CB Candy pedals on it. I had been using SPDs, but thought I'd give them a fair shake since there are so many zealots out there for them.

Eventually I pulled them off the bike and put on another set of SPDs. My foot could never find that "just right" spot to actually clip in, and when I could clip in, I could not clip out with out heroic efforts...like falling down, taking my shoes off and fighting to twist them out of the grip of the pedals. Granted this was on a mountain bike in the wilds of the Pacific NW with the only thing to hit was a tree, shrub, rock, log, wolf, etc. and not on a commuter bike. Your results may vary.

OP: I'd get the one that costs the least. I'd even recommend the Welboro knock-offs of the same pedals, I have them on one of my mountain rigs.

+1 Double sided for me. I can easily walk in SPD shoes. I use these on road bikes. It's not uncommon to see road bikes with SPD or egg beater pedals.

I recommend the 520, it's the better value and equally durable.

I agree. SPDs have better axle bearings, they're adjustable, and they don't treacherously spin underfoot when you're not engaged.

Have you considered the A530? I installed these this week and they are fantastic. I like that one side is platform and doesn't require a SPD cleat.

I've used 520's and 540's and couldn't tell a difference.

I've got Shimano PD-M540s on several bikes and they are great pedals. I got the 540s rather than 520s because the price wasn't that much more online if you shop around. The 520s might be every bit as good, but in my experience the more expensive (but not most expensive) Shimano parts have better bearings and last longer.

I've stuck with SPDs over the years because my original set of Wellgo SPDs are at least 10 years old with 10s of thousands of miles and still work great. They are great for commuting because they are double-sided and easy to click in. Tension is also easy to adjust.

I don't know about the Candy pedals, but the Eggbeaters don't have a spring tension adjustment. They don't need it. They are easy to both engage and disengage. You never have to look to engage them because they are 4-sided. Accidental pulling out under hard pedalling generally isn't a problem (at least not for me or that I have really heard about for others). I know a guy who is an extremely strong cyclist who gave away his spd's and switched to Eggbeaters on all his bikes. He hasn't been pulling out of the pedals unexpectedly. Overall, my Eggbeaters have worked flawlessly for probably a couple thousand miles. When not engaged, I haven't had more trouble sliding off the pedal than I previously did with spd's.

I have heard that some Eggbeaters need to be rebuilt more often than other pedals. I understand this has been corrected with the mid- and high-end versions. However, like I said above, my first pair has a couple thousand miles and is still going strong. I wonder if the critical comments in this regard are overstated, or maybe it's somewhat dependent on how they are used (mountain vs road, etc.).

Maybe your Candy pedals were defective. It really shouldn't be that hard to unclip - should be almost effortless.

Just to reiterate, in the case of the M520 and M540 pedals, there is no structural difference between the 2 in spite of the price difference. The exploded parts diagrams are here
https://techdocs.shimano.com/media/te...9830608616.pdf
https://techdocs.shimano.com/media/te...9830608614.pdf

and the only difference is part #2, the lock bolt.

I have one set of 540s and four sets of 520s. I can't tell the difference between the two, except that I can't use a 15mm wrench to remove the 540s. If these are your first set of clipless pedals, go with the 520s.

Yes I was initially drawn to Egg Beaters, but, after some research it seems as though the SPD's are more popular.

To OP: I don't think you'll go seriously wrong either way. I have an old pair of 520's on my commute bike and they are just fine, no issues, easy to snap into or clip out of; spin freely with zero maintenence.

By the same token (pretty much), I think you would be happy with the Crank Bros. Egg Beaters. I use them on my fixed gear bike just because the 4-sided-ness makes them an easy (albeit moving) target when clicking in. Again though, no problem snapping in or clicking out and no problems even with zero maintenence.

Rick / OCRR

M520s, they are almost always on sale at Performance.

M520's here too. Excellent budget pedal. 15 minutes worth of adjustments out of the box and I was on my way.

I was in the same dilemma: I had to choose between Shimano PD-M520 and Shimano PD-M540.

In order to decide, I looked at the diagrams provided by Shimano:
Shimano PD-M520 has a slightly different design than Shimano PD-M540, which shares the same design with the more expensive Shimano PD-M770 (Deore XT) and almost the same design as Shimano PD-M970 (XTR) - only the "body cover" has a slightly different design on XTR pedals. The difference between those 3 models (PD-M540, PD-M770 and PD-M970) is given by different materials on some parts and/or different finish on some parts.

Also, PD-M540 were only slightly more expensive than PD-M520 at the shop where I purchased them.

It was helpful reading through the responses, thank you. I'm going with the 520's, and might buy a light with the extra money....

My LBS made the decision - they had M540's in stock. I love 'em. I put 11,000 miles on my first pair before deciding my backup bike needed them - so I bought new M540's and put them on the "good bike" transferring the old pedals to the backup bike. No maintenance issues whatsoever. I keep the tension very loose, have never unintentionally unclipped but they released easily avoiding knee torque during crashes.

I recently went through the same decision as well. I went with the 540's myself. The price difference was not that much. Purchased a new set off amazon and they did include a set of cleats.

The difference in weight was not really noticeable when holding a 540 in one hand and a 520 in another, was not too worried about weight. Did prefer the look of the 540 and the axle was a smaller diameter.

I do have to note, the 540 is much better than me last petal. I was using a dual platform/spd m324. Much smoother and no worrying about having to turn the pedal to click in.

Go with the 520s. They're very reliable, super easy to use, easily adjustable, and generally better than most pedals that cost very much more.

(Disclaimer: I don't actually like any clipless pedal as much as a regular platform pedal. For commuting, I think they're a bit of a pain in the ass.)