Why is racing on a 10-speed bike faster than racing on a mountain bike?

Question

I know my question "outs" me as a newbie, but I never understood why mountain bikers ride slower than those on 10-speeds in races. Also, I race on a 10-speed, but I ride as slow as the mountain bikers. I'm in great shape but I can't understand why I lag behind the group in races. I'm sure it has something to do with the gear shifts, but I never learned how those worked. Can someone help out this first-timer?

the race in question was a triathlon.

Answer 1

What type of racing? Mtn, road, cyclocross?
Thanks, The main reasons mtn bikes are slower in this type of racing is gearing and tires. The other differences between the two types of bikes that keeps mtn bikes from being as fast are bike weight and a poor aerodynamic rider position, but tires and gearing really limit the speed of a mtn bike. Concerning your statement that "I'm in great shape but I can't understand why I lag behind the group in races" just being in great shape does not mean you are in great biking shape. In a triathlon you need to be in great overall shape, which means you will might excel in one discipline, but not all three.

Answer 2

Gearing:
For a road bike used in triathlon, a good "average" gear would be 52 tooth front ring and around a 14 tooth rear cog (which means you're on the big ring near the pedals, and about the third smallest on the rear cassette). Typically, they're turning their feet over pretty fast as well ... like 90 rpm.
Add in the tire size (700 mm diameter) and we have ...
(Speed) = (Cadence) * (front / rear gear) * (3.14) * (tire OD)
= 28942 inches per minute = 27.4 mph

Now ... same cadence (foot speed) on a mountain bike (26 inch tires, 44 tooth front ring, 15 tooth rear cog) ...
Plug everything into the same formula and you get
(Speed) = 21564 inches per minute = 20.4 mph

Stronger cyclists can maintain a higher foot speed (cadence) at more effort (higher gear ratio). If you're in a lower gear or can't move your feet, you're going to be slower.

Part of the perceived effort is related to aerodynamics - and a road bike puts the bike and the rider in a more wind-friendly position. Another part fo the perceived effort is actually accelerating the weight of rider and bike ... so a lighter bike and/or rider will tend to go faster for the same amount of energy output.

Depending on how you "feel" the best on your bike, you fall into one of two categories. You could be a spinner ... who moves feet rapidly (cadence = 95-110) but generally choose one or two gears easier than the others. Or perhaps a masher ... who moves feet slower (cadence = 75-85) and use higher gears to make up the difference. In the long haul, a masher uses more energy than a spinner, particularly with strong headwinds and/or climbs involved.

I know there's no "drafting" allowed in most triathlons. However, if you can find a group to train with that ONLY rides bikes, you'll be able to use drafting to your advantage. You'll find that as you ride farther (and faster, since a group will almost always travel faster than an individual), you'll build up your own technique and strength, plus pick up technical tips to make you a better cyclist. Who knows? Some of those cyclists may also be triathletes (or at least involved in something other than just cycling) ... and you can glean more details from them regarding other sports.

Answer 3

Firstly, there is the weight issue. Mountain bikes tend to be heavier, since they have suspension and sturdy components, which add weight.

The next thing is role resistance. Mountian bikes have thick tyres, which run at a lower pressure than road tyres. This means that your tyres grip the road, but also slow you down a little.

MTB wheels are usually 26", although there are some 29" versions. Road bikes have larger wheels. These are slower to get going, but once you are up to speed, you are faster.

Finally, the gears are set up differently. Think about a road car vs a 4 wheel drive. The 4 x 4 has more grunt and low down speed, whereas the road car will have smoother acceleration and top end, since it is not envisaged that a road car will need to cope with boggy fields and dirt tracks. The same happens with a mountain bikes gear ratio. The MTB is responsive and nimble on single tracks and can climb up rocky dirt tracks, but on tarmack, where the lighter design and skinny tyres count, the road machine will be faster.

Luck

Answer 4

Lots of small reasons, that add up to a big difference.

But the 2 main factors are:
-heavier wheels / tires / knobby tread = slower on pavement
-mtb's have a more upright position = more wind resistance

The gearing may be an issue but only at the very top end of the speed range. Once you figure out how the shifting works, and how to keep your pedal cadence in the most efficient range, that won't be an issue.

Also - remember the rest of the group is _also_ in great shape.

Tips: either get a road bike if you're serious and have the cash, or at least switch your mtb to "slick" skinny tires.

Good luck
Scott

Answer 5

For the same reason that a Ferrari goes faster on the street than a Hummer. Road bikes are built for pure speed, and everything on them is built for efficiency. From the 120 PSI tires with tiny contact patches for low rolling resistance to the aerodynamic rims and frames to the higher gearing that allows higher speeds without spinning out.

Mountain bikes have lower gearing, a more upright position, more weight, higher rolling resistance and poor aerodynamics.

If your bike doesn't fit properly, you will be inefficient. Learn your gears well, and you can always be in the proper gear for the terrain you're on, also.

Answer 6

There are many reasons a road bike is faster than a mountain bike:

1. Gear set - the gear ratios offered on the different types of bikes allow for different speeds and/or climbing leverage.

2. Wheel size and tire width - larger, skinnier tires on road bikes provide lest friction resistance against the road.

3. Geometry/body position - Road bikes allow a more aerodynamic stance that provide for less wind resistance.

Both types of riding are fun. I personally ride a flat-bar road bike, which gives me the larger, skinnier tires and a a wider gear cassette so I can ride fast but climb easily, but do not have to hunch over so much (which allows me to see more of the traffic on my commute). Have fun and ride often!

Answer 7

The idea that you called them "10 speeds" outs you as a newbie. They are actually called road bikes. No road bike has 10 speeds anymoreand haven't been for almost 20 years. I have three road bikes: 2 with 20 speeds and one with 30 speeds.
Anyway, in response to your question, road bikes are designed for speed. First off, the position of the rider on a road bike is aerodynamic for the lowest amount of wind resistance. They are quite a bit lighter with stiffer frames and the thinner tires equals less rolling resistance on paved surfaces. These factors make the road bike the most efficient device ever created. You can go fast with minimal effort because of this.

Mountain bikes arre designed for rough terrain. You wouldn't want to go road bike speeds on loose, dirt terrain that isn't necessarily a controlled environment- unless you ride a specially designed downhill mountain bike. Mountain bikes tend to be a lot heavier and the fat knobby off road tires are designed to go off road- not on. When used on the road, the wheels spin loudly and wear out faster than road bike tires. because they are designed to grip the surface- great for dirt; horrible for asphalt.

The reason why you are riding as slow as the mountain bikers is because you don't have enough time in the saddle- you lack experience. The more you ride, the more in tuned you will be with your bike and the faster you'll ride especially if you are trying to ride fast all of the time.

If you are riding an actual 10 speed bike, you have a bike that is way behind in technology- meaning you will have to work harder to ride this bike as fast as you would with a newer lighter road bike. Newer models are lighter, easier to ride fast and have closer gears that are much easier to shift than an old 10 speed.

Your weight and the weight of your bike does make a difference in how hard you have to work to maintain a high speed. There's more to riding a bike than just getting on and pedalling somewhere. Most people are inexperienced even after years of bike riding. Buy some books on cycling or go to the library and read some. Another good option is to go to your local bike shop and get their advice.You may find that your feet are positioned on the pedals incorrectly or that your seat or handlebars are the wrong height. Maybe you're riding the wrong frame size. A bike should fit you like a well-tailored suit. Good luck.

Answer 8

This Site Might Help You.

RE:
Why is racing on a 10-speed bike faster than racing on a mountain bike?
I know my question "outs" me as a newbie, but I never understood why mountain bikers ride slower than those on 10-speeds in races. Also, I race on a 10-speed, but I ride as slow as the mountain bikers. I'm in great shape but I can't understand why I lag behind the group in races....

Answer 9

This is not so simple as it first seems.

As scott.braden points out, for mechanical reasons Mountain Bikes are usually slower on asphalt. But, just try to ride a "10 speed" on a rough/muddy/dusty/rocky track and the results would be reversed. The bikes are made for different condition and each is good for its specialty.

Then there are other factors that make it tough too.

Riding in a group is not just about pure fitness but also subtle skills and abilities. You must learn to ride close to others to "draft" and reduce wind resistance, this takes time and coaching to get the hang of it.

Road riders tend to change pace more than Mountain Bikers and Time-Triallists. The constant variation in speed that you get in a group can be difficult to cope with when you are not used to it.

I know folk who just can't handle the higher speeds and pace changes of "bunched riding". On their own they superb athletes, nearly as fast as a group but lacking in bike-sense/handling and confidence. Stick them in a "chain-gang" and they just dangle off the end of the line like a yo-yo, puzzled why slower riders can stay with the group but they can't. In the end that's just as tiring as being on their own but they are going 3 -10 Km/h faster. Eventually the 'elastic' snaps and the rider is dropped from the group.

Modern gears are so good you lose very little time shifting and the higher gears on road bikes are there because they go faster, you need them to maintain speed, just as MTB gears are very low to cope with rough/steep ground.

You will get better if you practice and train regularly with a road club/team. Try to find a coach who can teach you the ins-and-outs of group riding.

Give it a go- you can only improve!

Answer 10

If you were to do a mini time trial, with each of the bikes the MTB bike would take more energy to get it down the road at the same speed - why - Its about 95% tires.

if the MB guys are beating you, their just in better shape than you are.