Confused about clipless pedals - the 2 hole versus the 3 hole types
 

I have both a mountain bike and a road bike. Looking around, I have noticed that the mountain bikes use the 2-hole SPD style pedal while the road bikes typically have the longer 3-hole style. Why is that? Is there an advantage to using the 3-hole type on the road bike as opposed to the 2-hole type? I've heard that the larger platform of the road pedals is better, but if the entire shoe is stiff--doesn't the shoe sole become the pedaling platform?

the 2 hole cleats are SPD's and the 3 hole is look compatible.. Most shoes come with both of these as a standard.. The type of cleat used is dependent on the pedal system you use..

Right.

But I wanted to know if there was an advantage to using the Look/SPD-SL on the road rather than the SPD that is so ubiquitos on the mountain bike--for instance.

No, they don't. Most MTB shoes can only accommodate a recessed, 2-hole cleat (SPD, Crank Brothers, etc). There simply isn't enough room to accommodate a 3-hole Look-compatible cleat. Many road bike shoes include both 2-hole and 3-hole bolt patterns... but just as many don't.

To answer the OP's question: the idea that large 3-bolt cleats are better than their 2-bolt competitors is left over from the days before cycling shoes had really stiff soles. If you've got a good shoe, it almost doesn't matter what the cleat looks like. For the sake of simplicity, I use SPD shoes and pedals on all of my road, touring, and mountain bikes.

Here's my semi-newbie explanation, which should be good enough for the internet.

The 2 hole and smaller cleat for mountain biking makes it easier to have treads on the shoe so you can get traction when you have to walk or carry your bike. Road bike shoes don't need tread, so the bigger cleat is used. I was told the bigger cleat is a little more stable, even though the shoe is stiff, and less chance for hot spots on your feet. Yes, the shoe does become the platform, but it is not as stiff as the pedal.

I used campus pedals that came on my hybrid with the 2-hole cleats when I first bought cycling shoes. Later, I switched to the 3 hole bigger cleats and got shimano road pedals. I like the bigger cleats better. They do feel more solid, I think it is because the contact area is larger. And the big cleat, road pedals are easier to clip in my second foot without looking for me.

What I was told is that in theory the Road-style pedal allows for more torque to be applied, and for the pedal to be a bit more lightweight. MTB pedals are more designed to shed dirt/mud, and to be durable - so they're heavier.

Again, this is what I was told, and I also know several people who use MTB SPD's on everything, including road bikes. I'm a huge fan of the MTB SPD's, personally, particulary the Shimano PD-M520's.

When I asked this question the answer was:

The larger platform on the road pedals are more comfortable over very long rides as they spread the weight.

However another thing that comes into play is mud shedding which I presume smaller cleats are better at.

I moved from road pedals to mtb pedals coz i needed a better commuting pedal. I noticed a difference in transfer of power. I thought I wouldn't but I did. Not sure if this is down to different type of pedal, or a different type of shoe (my road shoe is a specialized bg comp, the mtb one is a bg sport).

Also, I'm not claiming there WAS a differnce in power, but it FELT like there was, and the feeling was noticeable.

Thanks Ben and MrClyde.

I was told that the larger platform allowed for a better transfer of energy, but assuming that the shoes are completely connected with little play, to me it didn't matter if the cleat size was the size of a wallet or the size of a dime.

The weight concern--ah...that makes sense to me (perhaps more sense if we weren't Clydes anyway).

I was pondering this because of the recent store sales, I was wondering if it would be a good idea to swap my M520's on the road to another style.

Daven--that makes sense assuming some type of flex in the shoe. But I have seen some really stiff SPD shoes with very little compliance that offered less flex than the road shoe.

Mustang--that very well may be, if the other responses are, indeed, true.

Thanks for the responses. With what I'm hearing, my experience is beginning to make better sense now. After a century, I couldn't wait to rip my shoes off. I'm wondering if the 3-hole types would allow for more comfort. Interestingly, their are some road-focused egg-beaters out there, and those have very little platform to begin with.

Shameless Hijack-----

Where do you ride your MTB around San Diego? I am planning on going to Elfin Forest this Saturday, and in the future Daley Ranch, Mission Trails, Lake Hodges. Any good spots not to miss?

Yep only if there is flex does it make a difference. I wear stiff although walkable MTB shoes with egg beaters and find no discomfort.

Again, I think you're listening to out-dated information: with current SPD pedals and a good shoe, I expect you're not going to notice any difference in torque/power transfer unless you're ready to participate in the Tour de France.

While road riders would like you to believe that their pedals are much lighter, there often isn't a lot of difference. My $35 Shimano M520 SPD pedals weigh 370 grams. $120 Look Keo Classic road pedals weigh 338 grams and $110 Shimano 105 road pedals weigh 322. If you spent a similar amount of money on an SPD pedal you could get something in the same ballpark, weight-wise (M540 @ $90 = 346g, for instance). And lets not forget that Crank Brothers EggbeaterMTB pedals are super-light (Eggbeater SL @ $110 = 266g)! You could spend $300 on road pedals (e.g. Shimano Dura-Ace) and still not match that weight...

Shameless hijack answer!

Lately, we've been riding around the easy trails in Chula Vista. I've heard some nice things about the Penesquitos trail and should be trying that sometime (assuming the weather cooperates).

You could. I wouldn't. But you COULD.

I spent $130 on Keo Carbons. They weigh 230g. What's your point?

Honestly, the weight difference is pretty insignificant in the scheme of things, but 'MTB' pedals, on AVERAGE, weigh MORE than 'road' pedals.

2-bolt SPDs are plenty capable. 3-bolt cleats have a wider physical structure and DO support the shoe sole better....that is...less lateral flex. With an extra fixturing point, theoretically they would also be less prone to slip or twist.

What are 'good' shoes anyhow? Are they shoes with absolute zero flex front to back? Side-to-side?

To me, 'good' shoes are comfortable, and when paired with my cleats/pedals....remain that way.

If you're putting enough lateral force on your SPD's to make the cleats twist then you're pedaling wrong.

I think it is like a lot of things in cycling, there may not be a scientific reason, but some things feel different than others. Using the same shoes, I used the 2 bolt then switched to the 3 bolt. The 3 bolt feel more "solid". By this, I mean it feels like more of the pedaling effort goes to propeling me forward. This was with the same shoe.

So I like the 3 bolt, and for me they are easier to clip in as well.

My point, which I thought was pretty obvious, is that pedals designed to work with 3-hole cleats aren't necessarily lighter than pedals designed to work with 2-hole cleats. There are quite a few heavy 3-hole/road pedals out there and, correspondingly, there are quite a few 2-hole/MTB pedals that are relatively light.

I, personally, can't tell the difference between my 370g M520 SPDs and the 270g Crank Brothers pedals they replaced so I'd suggest the OP not focus on weight as a deciding factor when selecting a clipless pedal system.

If I continuing being on the north side of 200 pounds, there is no way that the extra grams in the pedal would matter much to me.

I was just wondering if there was a functional difference among the pedals for the road vs offroad application.

I have Egg Beaters on all my bikes. I only need one pair of shoes that way, and mountain bike shoes are much easier to walk in when stopping to take a break on road rides. I do notice a difference between the stiffnes of the cheap shoes I started with and the pair I have now though.

I like mtb shoes and pedals but I can't keep up with the guys that wear road shoes and pedals so it doesn't matter.:D

i can't keep up with 5 year olds on tricycles so it really doesn't matter to me!

The biggest functional difference is being able to walk normally in mtb shoes.

Also for weight savings, I think most of the saved weight would be on the shoes and not the pedals.

One other advantage of the SPD pedals for a road bike is that there are quite a few pedals available that have an SPD mount on one face, and the other is a traditional flat pedal face, for use with regular shoes. That doesn't really matter on a bike that you will always ride fully geared up, but it is handy to be able to just hop on the bike with regular shoes on if I'm just on a short jaunt with my five-year-old.
(There may be similar pedals for look-compatible cleats, but I don't recall seeing them.)

I have found one brand of shoe that does have the 3 hole bolt pattern and a tread for walking when off the bike. I would buy it but they don't come in a wide size. This may be an option if you have a few bikes with look style pedals and don't want to replace all the pedals.