Condensed answer: Road and mountain bike pedals designed for adults have the same pedal thread (9/16” x 20 TPI). As a result, you can easily swap pedals between bikes.
There’s nothing wrong with using mountain bike pedals on a road bike. Some people even do it on purpose to enjoy the benefits of MTB shoes and pedals.
If you’re a serious road racer, however, road-specific pedals are considered optimal.
Technical Requirements For Installing MTB Pedals On a Road Bike
1. The Pedal Threads Should Match
If the pedals and the cranks have non-corresponding threads, you won’t be able to mount the pedals.
Luckily, most pedals have 9/16” x 20 TPI threads:
- 9/16″ (14.3mm) indicates the diameter of the pedal’s threaded part.
- TPI is an acronym for Threads Per Inch and shows the number of threads per 1 inch/2.54cm. In this case, the threads’ density is 20 per inch.
Note: The threads of some pedals are 1/2″ thick, but those models are usually restricted to low-end and children’s bikes. Nonetheless, it’s wise to read the information on the packaging before buying new pedals.
2. Proper Cleats
Clipless mountain and road pedals use different cleat systems. MTB cleats are recessed and mount via two bolts whereas road cleats rely on a three-bolt mounting system and have a different shape.
This leaves us with three main options for using MTB pedals on a road bike:
- Buy MTB shoes
This is the simplest but also the most expensive route unless you’re also an MTB rider and already have MTB shoes.
- Road-to-MTB Cleats Adapter
Another option is to install Road-to-MTB adapters on your existing cycling shoes. The downside of this approach is that you won’t get the benefits of MTB shoes.
In some cases, the adapters may be quite expensive to the point where it seems wiser to just go for MTB shoes.
- Use Multi-purpose Cycling Shoes
Some cycling shoes are designed to accept both MTB and road cleats. Unfortunately, those models are usually low-end. And since they have to work with road cleats too, the cleats stick out when installed.
Ultimately, you’re getting a cheap road shoe with extra holes for MTB cleats drilled into it. For that reason, hybrid shoes cannot classify as MTB and are not recommended for actual MTB riding.
MTB vs. Road Pedals For Road Use
The advantages of using clipless MTB pedals on a road bike are:
1. Easier to Clip in and Out
Most people have an easier time clipping in and out of MTB pedals than road ones primarily because MTB pedals have a mounting system on both sides.
Conversely, road pedals are one-sided, and you may have to flip the pedal over to clip in.
2. MTB Shoes Are Better Suited For Walking
The cleats of MTB shoes are embedded deep into the sole and do not stick out. This property makes walking in MTB shoes a lot easier and preserves the cleats because they aren’t in contact with the ground.
In addition, MTB shoes have treads designed for walking on off-road terrain.
In different, the cleats on road shoes stick out. As a result, walking becomes very uncomfortable and damages the cleats which are usually made of plastic that can’t fight against the asphalt.
You can definitely use MTB shoes on a road bike, but the opposite isn’t true. Road shoes and pedals installed on an MTB will result in massive underperformance on the trail and may even cause an accident.
If you have two bikes (MTB + Road), and you want to make things simple, installing MTB pedals on both machines and relying on MTB shoes exclusively is the most efficient and convenient strategy.
4. Casual Look
MTB shoes blend in with a sports outfit. Conversely, road shoes are attention grabbers (not in a good way) and look their best only when in use on a bike.
5. No Need For Two Pairs of Shoes
If you have to engage in a non-cycling activity before, after, or during a ride, you will have to bring another pair of shoes if you want to walk safely and comfortably.
And as we all know, cyclists don’t like to carry lots of stuff, especially when doing mundane tasks.
6. Better For Commuting
If you use your bike for commuting, MTB shoes win because they allow you to walk normally. This makes running errands on a bike with clipless pedals a lot easier.
Also, if your bike breaks down, and you can’t fix the issue on the spot, MTB shoes will make it easier to get help because you will be able to walk efficiently.
Conversely, walking multiple miles in road shoes is detrimental to your health due to the stress on the joints and the possibility of falling.
7. Better For Bike Messengers
If you’re a bike messenger and want to use a clipless pedal system, MTB pedals + shoes make the most sense. You will have a much easier time getting off the bike and walking to an establishment to deliver a parcel.
That said, most bike messengers use either flat pedals or flat pedals with straps because those combinations make it possible to ride with all kinds of shoes.
Some people switch to MTB shoes during the winter for extra warmth.
9. Durable Cleats
MTB cleats seem to last longer than road models.
The disadvantages of running MTB pedals on a road bike:
MTB clipless pedals are heavier than their road equivalents.
The table below contains the weight of popular MTB and road pedals:
|Shimano DXR PD-MX70 SPD||414g||Shimano Ultegra PD-R8000||248g|
|Bontrager Comp||316g||Shimano Dura Ace PD-R9100||234g|
|Shimano Deore XT PD-T8000||392g||Time Xpresso 7||198g|
|Shimano PD-ME700||540g||LOOK Kéo Sprint||280g|
|Shimano PD-M520||380g||Shimano 105 PD-R7000||265g|
|Shimano PD-M64||568g||Exustar E-PR200BK Pedal||244g|
|Shimano Saint PD-M820||586g||LOOK Kéo 2||260g|
|Shimano Deore XT PD-M8100||342g||Exustar E-PR50 Pedal||262g|
|Shimano PD-ED500||450g||Campagnolo Record Pro-Fit||266g|
|Shimano Deore XT PD-M8120||432g||XLC PD-R04||285g|
Conclusion: Road pedals are substantially lighter. However, the heavier MTB models on the list are designed for downhill and enduro and have a larger platform.
If you want to save weight, you can go for slimmer MTB pedals. In that case, the weight difference drops to 100-150grams – a number that a recreational cyclist wouldn’t notice.
2. A Smaller Platform
Apart from enduro models, MTB clipless pedals are slimmer than their road rivals. Some people consider that a negative because a greater contact area improves comfort and increases power transfer.
3. Lack of Efficiency on The Road
MTB pedals require MTB shoes. The combo is very effective, but road bike pedals + road shoes provide slightly greater efficiency when cycling on the road.
The difference may not be huge, but it matters to serious cyclists who want to get better times. For that reason, professionals stick to road-specific equipment.
But most people aren’t and will never be on that level. The extra seconds that one saves from using road pedals + shoes do not outweigh the discomfort that road cleats create.
What About Flat Pedals?
If you want, you can install flat MTB or BMX pedals on a road bike too.
Flat pedals have the following benefits:
- No learning curve
Clipless pedals aren’t “natural” and require some time to get used to them. Many people fall before perfecting the technique which is why it’s recommended to ride at a deserted place when trying clipless pedals for the first time.
Flat pedals are the polar opposite. If you know how to ride a bike, you know how to use flat pedals.
- Shoe “Freedom”
Flat pedals allow you to ride with all kinds of shoes.
The cons of flat pedals for road riding are:
- Inefficient power transfer
Clipless pedals attach your foot to the pedal and give you the necessary connection to insert maximum power on both the downstroke and the upstroke. Flat pedals are inefficient on the upstroke because you can’t pull the pedal as much.
Therefore, if maximum speed and efficiency are your goals, flat pedals are technically sub-optimal.
Under real-world conditions, however, flat pedals can be surprisingly effective for non-racers.
If you combine grippy flat pedals with good shoes (e.g., Five Tens), you will get plenty of grip and the gap between flats and clipless will be minimized.
Summary: What You Need To Know
1. If the pedal thread matches that of the cranks, you can install any pedal you want. Most pedals have a 9/16” x 20 TPI thread.
2. MTB pedals have two-bolt cleats whereas road models use three-bolt cleats. For that reason, you can’t use road shoes and MTB pedals.
3. MTB shoes have a great number of benefits such as:
- You can walk in them – a quality that makes MTB shoes superior for recreational riding and commuting.
- Casual look allowing you to combine them with basic clothes
- Large tread for grip on off-road surfaces.
- The cleats are recessed and last longer.
4. Road shoes maximize power transfer on the road, but the gains are too small to matter to recreational cyclists.
For that reason, some people believe that road pedals should only be used by racers whereas the rest of the road crowd should go for MTB pedals and shoes.
5. You can install flat MTB pedals on a road bike too. If you get a grippy model and combine it with a good shoe, it will be surprisingly efficient.