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-   -   Mountain Bike Century (https://www.bikeforums.net/general-cycling-discussion/96431-mountain-bike-century.html)

Portis 03-31-05 03:41 PM

I have never really spent much time on a Road Bike. I am aware of the stated differences between a MTB being geometry, weight, tires, gearing etc. However, I know that the engine is pretty important as well. My question concerns the DEGREE of difference between the Road Bike and the Mountain Bike.

If I were to do a century in exactly the same weather conditions on an entry level Mountain Bike with 1.4 Slick tires how much slower would I be than if I rode an entry level road bike. I just want a general answer as i know there are other variables such as gearing on the respective bikes.

I just want a general idea. How much longer would it take to do the 100 miles on the MTB?

hillyman 03-31-05 03:53 PM

I would think difference is more aerodynamic than anything unless you can push a 52 tooth alot.

LordOpie 03-31-05 04:00 PM

Isn't the diameter of the wheel a factor? If so, then a road bike would be 27/26 times (4%) more efficient (plus whatever other factors), right?

EDIT: but the mt.bike would allow you to do an off-road century and that's mas macho! Like White Rim in Utah.

snowy 03-31-05 04:07 PM

Maybe you should look into getting an inexpensive road bike and do a century. Then you can really test and see if you want to invest more into a roadbike. I never thought I would get on a roadbike, but I love it now and my mountain bike is getting dusty. Try it and see if you like it.

spindog 03-31-05 04:21 PM

I rode my first six centuries on a mountain bike. Two with knobbies and the last four with slicks. Each ride, I managed to ride with roadies and they were amazed that I could keep up. I didn't know any different and had no idea why my ride should be more difficult than theirs.

When I finally switched to a road bike I felt weightless. How much faster was I? I never had a speedometer on the mountain bike, so I'm not sure. But I do believe that riding the heavier bike and spinning my butt off to keep up with the roadies helped me to develop a real efficient pedal stroke and made me a stronger rider.

The one thing that sucked about riding the mountain bike with slicks was that the wide suface was a magnet for every little particle of road debris and flatted WAY too often. (advice - never ride a century in the rain with mtn bike slicks)

My guestimate for speed loss/gain with equal effort would be -for example, if you comfortably rode a century averaging @ 17 mph on a road bike, the mountain bike w/slicks, given the same effort would be more like 15ish mph. (But you'd crank on the downhills!!)

Sorry for the babbling - Of course, I have no scientific or measurable answer for your question.

telenick 03-31-05 05:30 PM


Originally Posted by LordOpie
but the mt.bike would allow you to do an off-road century like White Rim in Utah.

White Rim in a day.

It's an annual event every October two weeks before the 24 hours of Moab. Kind of a team pow-wow and to see who has legs.

It takes us 12 hours at a gentlemanly competitive pace. But you gotta haul all your water from the start. I take 1.5 gallons.

Woof!

SpiderMike 03-31-05 05:32 PM

I did my first metric century on old beater Mt. bike. I had used it for city commuting primarily. I had changed out the chain rings to something like 48/38/28, the cassette was 13-34. I had put some dyno fireball balloon cruiser tires on it. For the most part I kept up with the roadies. At one stop, a group looked at my bike, and told me it was a torture device.

There was only one sketch part. At the beginning of the ride was the Fred Hartman Bridge. http://www.bayareahouston.com/Home/P...LaPortejoinsP/ Going up was ok. Going down was another story. I had max out my gears on the way down, and the bike started getting the high speed wobble. 5 minutes after the bridge I came up on a roller bladder that looked more stoked than I felt.

LordOpie 03-31-05 05:44 PM


Originally Posted by telenick
White Rim in a day.

It's an annual event every October two weeks before the 24 hours of Moab. Kind of a team pow-wow and to see who has legs.

It takes us 12 hours at a gentlemanly competitive pace. But you gotta haul all your water from the start. I take 1.5 gallons.

Woof!

Am I to understand that you drink 16 ounces/hour? I think I'd need nearly double that? No aid stations, huh? Someone should organize a supported White Rim event.

DCCommuter 03-31-05 05:58 PM


Originally Posted by LordOpie
Isn't the diameter of the wheel a factor? If so, then a road bike would be 27/26 times (4%) more efficient (plus whatever other factors), right?

The importance of wheel diameter is way over-rated. The reason road wheels are 700c is that's the size that road wheels come in. Tire selection and wheel construction is much more important than wheel size, and it's much easier to find wheels and tires built for speed in the 700cm size. I've recently read about two trends. First, MTB manufacturers are now pushing "29ers" with so-called 29" tires that use 700cm rims. Second, road bike manufacturers are now pushing bikes with 650cm rims -- 26" for those of you on imperial units. It seems each side is convinced the other side is right!

It would be a good thing for the industry to move away from rigid standards. It's silly not to have wheel size scale with frame size. Short riders in particular suffer -- it's hard (some would say impossible) to make a bike with acceptable geometry and 700cm wheels for someone under 5'4". Smaller wheels might help you get a better fitting bike if you are smaller than average.

Ken Kifer has a great riff on the subject:
"One of the oddest tales, and also clear proof of how us cyclists let ourselves be pushed around, is the story of tire sizes. When I started riding as an adult, all the bikes had 26-inch tires. My first "10-speed" (6 useful gears) came with 27-inch tires, forcing me to buy tires at bike shops (which are hard to find on a tour). A dozen years ago came a "great" improvement created by shifting from 27-inch to 700 cc tires. Article after article raved about the improvement. The only difference I can see is the need to stop at a bike shop rather than Kmart. Then came a new shift, where to? -- the 26 inch bike; only the tires on this bike are a different size from the old 26 incher. Can't you tell you're being flimflammed? Slight differences in the diameter of the wheel have no noticeable effect. The whole purpose of the different tire sizes is to force you to buy tires from one company rather than another or at a bike shop rather than a discount store."

telenick 03-31-05 06:13 PM


Originally Posted by LordOpie
Am I to understand that you drink 16 ounces/hour? I think I'd need nearly double that? No aid stations, huh? Someone should organize a supported White Rim event.

Yeah, kinda sparse hydration. Lugging 1.5 gallons ain't no piknik though.

We actually ride from Potato Bottom to Island in the Sky Ranger Station where we have water and food stashed. So, that's 80 miles with 1.5 gallons plus a lot of hydrating on the first 20 miles.

HaagenDas 03-31-05 06:26 PM

Some people have money :D

HaagenDas 03-31-05 06:34 PM

I'd settle for those neat plastic tassles that come out of the ends of your handlebars. :D

cdale56 03-31-05 06:35 PM

This year I have done two centuries on my heavy low end MT bike with knobbies and two on my road bike and I have seen about a 2 mph difference, but the rides were all different with different variables. (temperature, wind, road selection, terrain and other intangibles)

Blackberry 03-31-05 07:58 PM

I would say that the fat knobby tires of any MTB vs. the narrow slick tires of even the most entry level of road bikes would make for a pretty significant difference in rolling resistance. Not only would your speed be affected but the amount of work you have to do to cover the mileage would be impacted pretty heavily.

khuon 03-31-05 08:10 PM

I used to do offroad centuries on my MTB although I will say they were considerably slower than road centuries on my RB. Go figure. I never really did a pure road century on my MTB though but have ridden some half centuries with it. I will say that I probably average 2-3 MPH slower on my full-suspension MTB when compared with my RB.

Portis 04-02-05 10:08 PM

thump.

Machka 04-02-05 10:20 PM

I have done quite a number of centuries on my mountain bike, and also my first 200K brevet.

The mountain bike centuries do take longer, but not necessarily by very much. It depends a lot on weather conditions.

My mountain bike centuries are done in the winter, often in sub-freezing temperatures. They run about 9 - 10 hours depending on how cold it is, or if there is snow or freezing rain, etc. My road bicycle centuries, usually done in the summer when the weather is much better, and I'm in better shape, range between 6 and 8 hours.

However, I can tell you about my 200K brevets:
2001 - 12 hours - done on my mtn bike
2002 - 13 hours - done on my road bicycle
2003 - 10 hours - done on my road bicycle
2004 - 10 hours - done on my road bicycle

2001, 2003, and 2004 all had pretty good weather; 2002 included over 100K of an incredibly heavy headwind. So I guess, given similar conditions, over 200 kms, the mtn bike takes me a couple hours longer, than a road bicycle (about 3 km/h difference).

khuon 04-02-05 10:50 PM

I just want clarification for the continuance of the thread... I think we need to make a distinction between 100 miles with a MTB over offroad terrain vs. 100 miles on a MTB on the road.

Machka 04-02-05 11:23 PM


Originally Posted by khuon
I just want clarification for the continuance of the thread... I think we need to make a distinction between 100 miles with a MTB over offroad terrain vs. 100 miles on a MTB on the road.

My mtn bike centuries were always on the road. I rarely use my mtn bike in off-road situations unless the trails are covered in snow.

monogodo 04-02-05 11:52 PM

I did Hotter 'n Hell on my MTB twice. Once the full Century, once I sagged at 60 miles due to a flat. I actually enjoyed it more on the MTB than on any of my road bikes because my MTB is fully suspended.

http://photos4.flickr.com/7362322_6c10ce8e56_m.jpg

With barends, I had multiple hand positions, plus I tend to set up my MTB and road bikes so that I'm in the same basic position on both. I tend to stay in the small ring (39T) on my road bike, unless I'm going downhill, and in the large ring(42T) on the MTB (when on paved roads). With the slightly taller gearing, plus the 175mm (mtb) vs 170mm (road) cranks, I was actually able to maintain a faster average speed on my MTB than on previous rides on my road bike.

Doctor Morbius 04-03-05 12:09 AM

All I can say is I'm jealous as Hell of all of you. I've had a nasty case of bronchitis and on top of it I now have caught a cold. Have only had 2 rides in almost 3 weeks! :mad: <cough> <cough>

I had such high hopes for this spring and a century on my MTB was one of my goals. As of tonight I feel as though I've lost all of the fitness I'd worked for since the first of the year 700 miles ago. :( The worst part of it is I've been taking medication for about 2 weeks and it isn't doing any good. $90 for a 30 day supply of Serevent and it isn't making a dent.

Diggy18 04-03-05 12:20 AM

Don't know about a century, but my average speed on my knobby-tired MTB is about 12.6mph for a metric century. It sure feels like slicks and a more aero position would help in the long run. And also high pressure tires.


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