Speed advantage of roadbike vs mountain bike
 

I just started bicycle commute to school. I didn't want to spend a lot of money or worry about my bicycle being stolen, so I just purchase a cheap ($70) used mountain bike. It has a few minor problems, but it works for my purpose of commuting. I have been doing this for almost everyday for about two months and it has been worked out fine, especially with cool weather. But many times, I notice cyclers on roadbikes passing me with fairly quick speed.

Couple of times, I had to ride when I had cold. It made me sweat quite a bit and if I had to go to class right away, it was quite uncomfortable. I am beginning to worry about summer commute as I live in Southern California. I try to ride vigorously, before I start sweating (I sweat a lot), and I was never passed by other cylcer than on roadbike. Now it makes me want to purchase an entry level roadbike that is setup up properly for me. And the bike road in my area is setup quite nice so I don't think riding roadbike 100% of the time would cause me any problem.

So my question is, if I get an entry level bike from a bike shop (to have it setup properly and learn to ride correct/set up machine correct), how much of speed advantage would I get? I think I average 15~20 mph unless it's contiously uphill, which at that point I slow down not to sweat. So if I average 15 mph, how much of speed increase could I expect on a roadbike compared to the same work done on my crappy mountain bike? Also how much should I expect to spend on a roadbike from a local bike shop? Thanks in advance for any input!!

What kind of mountain bike is it and how is it set up? What kind of tires does it have? Does it have a suspension fork? How many teeth does your largest chainring (gear in the front) have?

Not sure if the bike makes that much of a difference. I have a nice road bike and get passed all the time. Sounds like you need to concentrate on the clothes with the right layers and go at a pace to arrive a school without a lot of sweat. Don't worry about the other cyclists - just pay attention to the traffic so you arrive in one piece. If anything, some higher pressure better tires. Unfortunately, a new road bike will probably be quickly stolen at your school even with a good ulock.

Visit your local bike shops and try out a variety of entry level ($500+) road bikes. Eventually you will want two bikes - one for commuting to school where if stolen won't be a big loss and a nicer road bike for longer rides on the weekend.

Have fun!

I have on old MTB I ride to work on days where there is no safe parking. Some days I'm lucky and the Kindergarten is fenced or I can park inside. Then I take the nice bike. Its really worth having a bike that rides nicely, but is inexpensive and really boring to look at. If it does get stolen you aren't out of pocket more than $150 or so. :) Also in summer sweat is unavoidable. I wear cycling clothes and just take along my work clothes in a bag along with a towel and baby wipes. The wipes take care of the sweat and you towel down for the rest. Only takes 5 minutes or so and all you need is a bathroom where you can get changed into clothes you can wear for the rest of the day.

On road bikes... they pass me on my mtbs all the time. I don't worry. I'm riding to my best ability and if they are faster, then I need to train more.

I just recently bought my first roadish bike (its a cyclocross bike), I used to ride exclusively on an old front suspension mtb. I use the mtb as my commuter and the cross bike as my fun ride. My average pace on the mtb is 15-16mph. Just recently I rode the same route with my cross bike just to see how big of a difference it makes and here is what I found. On the cross bike my average pace is 20mph and I work less to maintain my pace than I do on the mtb. Here are a few of the likely reasons for the increase. The mtb's front suspension absorbs some of the power from the pedals making it less efficient but more comfy. The mtb has smaller wheels 26x1.75 vs the cross bikes 700x33. The cross bike is lighter as well, it weighs 22lbs and the mtb easily weighs 30+. And the last reason I think my cross bike is so much faster is that it has clipless pedals and the mtb uses flats. SO in conclusion how much speed gain you will have switching from your mtb to a road bike depends on a lot of factors.

First of all, the road bike won't make you sweat less. What will make you sweat less is slowing down, not speeding up.

Second, before considering the possible speed advantages of a road bike, set up you MTB for speed. Putting on slick road tyres will make a big difference. Lock out any suspension.

Once you've done that, the advantages offered by road bikes are aerodynamics and weight. The former is the more important, riding in the drops saves a significant amount of power for a given speed. Weight matter most on hills, very little on the flat, and maximising the benefits costs a lot of money. Generally speaking, light=expensive. And at the end of it all, the difference in the speed of your commute won't be huge. On my most recent commuting route, which was about 16 miles, if I took the touring bike with panniers containing clothes, laptop etc. - about 45lbs in all - it took me 65 minutes. If I took the full carbon road bike, carrying nothing - about 17lbs in all - it took me 55 minutes.

Pay attention to the tires. If you have knobby tires, you can replace them with road type tires, on the mountain bike. This will be a significant reduction in resistance on roads. You can get new tires for under $20 each, look at models for road use that are 26", at ones on sale from online stores.

I ride an Mtb with 2,1 tires, a CX bike with 1,4 and several roadbikes with 23 or 25 mm racing tires. My commute is only 4 miles but the difference in speed is significant. My advice is (stingy retrogrouch): Get a good quality japanese roadbike from the eighties on CL. My 87 Team Miyata is as fast as my CF bike and in some respects a nicer ride.

Yep, that's why I first got a road bike. Not so much questioning are the road bike riders really faster than I am, but why not be as fast as your own potential?

Honestly though, the speed advantages for road bikes mainly lie in the wheels and tires, and in the aerodynamics of the rider position, and to a lesser extent less weight. From that base we wouldn't be wrong to say you can get close to the same speeds by changing the wheels, tires and rider position on a mountain bike to emulate that of a typical road bike. For a low end mountain bike only weight is the real downfall.

By the same token, unless it's an advanced cyclist he won't see much speed gain from the road bike.

There are two things that keep you from going faster: mechanical resistance, and wind resistance. Mechanical resistance increases linearly with speed, while wind resistance increases with the square of the speed. For an average bike, with a moderately upright riding posture, the mechanical and wind resistance are about the same, when you are travelling at 4 mph. This means that at 15mph, the wind resistance is 4 times as important as mechanical, and at 20 mph wind is 5 times more important. Very quickly, the only thing that really matters is the wind resistance - therefore, the key to increasing your speed is to present less wind resistance, which you do by moving your body lower, and more horizontal. You can do this on a mountain bike by hunching down and putting your chin on the handlebars, or on a road bike by moving your hands into the drops, the main thing that a road bike is doing for your speed is making it easier for you to maintain a more aero position. - If you really want to go fast, get a 'bent!

Road bikes are/can be profoundly faster than mountain bikes on roads with nice pavement. And they're lighter, transfer power more efficiently (especially if you have a shock absorber on the MTB), and they're much nimbler, they handle better. But they're not usually cheap. It might be a better use of your funds to set your current bike up to be as fast as possible, and then work on the engine.

But then the required beard slows you down, so it's a wash.

I think speed depends more on cargo than other stuff, I used to have a speedy bike and a sluggish workhorse and the more load I transferred to the speedy bike the more of a sluggish workhorse it became. Now I have a roadbike w/ no rack so I cannot have cargo creep (unless I go from a shoulder bag to a backpack I guess). The other 2 sluggish workhorses, well, one is pretty redundant but it does have some features making me keep it around for a while longer.

To attempt to answer your question, on one sluggish bike I can maintain 14-16 mph, on my new (to me) road bike I can push 17 mph sometimes, but not too often; w/ traffic and lights over 7 miles that's like a 1-2 minute savings. On that same road bike I can exceed 18mph average over much longer fun rides w/ no cargo and few lights.

Commuting is just different, so a 'properly set up road bike' will give you a max speed on long ride conditions that you will pretty much not be able to approach while commuting. And if you load your road bike the same as your mtn bike your speed will probably be identical.

Hahaha! Good one! That made me laugh out loud at work.

Commuting is just riding your bike to work, school, or some other place you need to be. Some folks enjoy bringing everything but the kitchen sink with them; that isn't a commuting thing, it's a personality thing. I mean, if you're a computer programmer, you don't really need to bring a bivvy sack and a lathe to work in case you get lost or have to produce a new spoke...

I commute in the clothes I'll wear, lock my bike up outside, and work at the computer that's waiting on my desk. The only 'cargo' involved is the spare tube and CO2. This is a lot like a recreational ride, only shorter.

But the required bent aerobelly negates the wind resistance of the beard.

If the MTB has knobby tires that will hurt speed far and above anything else for street/highway riding.

Don in Austin

A guy like me riding a road bike can blow by another guy like me riding a mountain bike like I'm standing still.

What does this mean in terms of my commute time? Actually, not that much difference. 3 to 5 minutes maybe over 6 miles. In a race losing by 3 to 5 minutes more than likely means that you're are well back of the leaders. For commuting? It's up to you whether that amount of time is important.

A shorter commute with a lot of intersections or other places you need to slow down will make the difference between a road bike and a mountain bike less noticeable. A long commute on open roads will be more favorable to a road bike.

Your not going to turn a 60 minute commute into a 30 minute commute by switching to a road bike. I think you'd be lucky to shave 10 minutes off. That's not an insignificant amount of time, but it may not be what you were hoping for.

I can ride my mountain bike just as fast as I can ride my road bike.

But I do a lot less work on my road bike.

Emergencies?

He bought it used, two months ago. How is he going to return it?

You tend to make wild and very presumptuous suggestions to people.

Hmmmmmmm ......... so just for the sake of argument, lets say you get that entry level road bike.

Now whats your next move when someone passes you on a carbon fiber mountain bike?

Correct. But that's what trolls do.

Enough already! I really hope some of the other posts in your 10 post per day average for the last two years are a little more of a positive contribution to the forum!

First off, it is much more the motor than the bike that makes speed. Of course all things being equal a road bike is faster than a MTB based commute bike, but there is a blurry area in the middle.

That said, my commute bike is an old 1980s Specialized Stumpjumper I got at a yard sale for 20 bucks. Of course I proceeded to put a bunch of money and time into it, and I do store it inside at work, but it is still ugly. The single largest improvement in speed (besides me loosing 80 pounds over the last 4 years or so) was going to 26x1.5 slicks that can be pumped to 100psi. My commute is around 5 miles one way, with an 800 foot climb. I can take 5 minutes off my commute up on my road bike easily, but, on our crappy roads in commute traffic I feel much safer on the dedicated commute bike (plus I'm not wearing out one of my treasured road bikes just getting to work).

Yard sale and/or Craigslist are great places to pick up a good starting point for a commute bike.

Enough of what?