dokterd1

If I put some slick tires on my Trek 800 can I expect similar speed as a road bicycle for commuting purposes? I figure the decreased rolling resistance will help alot.
Thanks

elvez

It helps a lot but I doubt it would be as fast as a road bike.

gitarzan

Gearing isn't the same, is it?

neil

A mountain bike is still going to be heavier than a true roadie, so it'll be slower on starts, and the gearing and weight will also keep your top speed down. Slicks on MTBs are usually still lower pressure than a road bike, so will have more resistance to overcome. If there's any suspension, that's again adding extra weight and an energy suck.

A mountain bike with slicks is probably more in line with a touring bike, or possibly a cross bike, but again, the gearing is still different, and any suspension will reduce the speed.

Tundra_Man 

You'll be faster, but not as fast as a road bike. Mainly due to the more aero position that a road bike puts you in versus the upright position of a mountain bike.

I have four different kinds of bikes. My average speed increases about 2 mph between each bike:

Knobby tired mountain bike: 14 mph avg or less.
Smooth tired hybrid: 16 mph avg.
Road bike: 18 mph avg.
TT bike: 20+ mph avg.

Loose Chain

The answer is no, it will be faster than it was but not nearly as fast as a road bike or even a cyclcross bike. I have all three types and have answered that question for myself, the answer is no, not even close.

I get almost exactly the same results as Tundra man above, a 2mph increase from:

mtb with knobbies -----> mtb bike with slicks ------> cyclecross with smooth center tires -----> roadbike on 25mm Conti GP40000 tires.

Yeah, I go from a sustainable 8 to 10 mph to a sustainable 16 to maybe 18 mph (unloaded).

wunderkind

Commuting is not always about pure speed.

groovestew

I've been doing my 10-mile commute in about 35 minutes on my road bike (23mm slicks), but this morning on my MTB with 1.5" semi-slicks, it took 44 minutes. There were other factors that slowed me down, but even if all else was equal, a proper road bike is definitely faster for me. That said, I've never tried 23mm slicks on my MTB. That would look silly.

Gearing I think is less relevant, isn't it? Unless you can spin out in top gear on your MTB, there's still a full range of gears. The differences between gears may be greater on a MTB cassette, so maybe there's a few seconds lost here and there with less smooth transitions, but I'm not sure that different gearing will make as much difference as tires, weight, posture, pedals, etc. I actually have road gears on my MTB now, and don't find they make me any faster. I just put them on so that the difference between gears is less jarring.

groovestew

It is for me!

tjspiel

Not all road bikes and MTBs are created equal. In a race if I had a choice between a 40 lb. Schwinn Varsity and lightweight, rigid framed MTB designed for racing that had street tires on it, I'd take the MTB. I know people who've bought 30 year old, low end 10 speeds to do a triathlon when they may have had a better bike already sitting in the garage.

If the idea is to shave time off your commute, the shorter the distance and the more intersections you have to deal with, the less difference it will make as far as which bike you choose. If your commute is lengthy with more significant open stretches, then the differences from one bike to the next will become more pronounced.

If you just like riding a fast, responsive bike, then a road bike can be a lot of fun regardless of distance.

mijome07

Please take me to school. What is a 'true' road bike and what is a 'fake' one?

AlmostTrick

Exactly. Unless you are going down a big hill, standard mountain gearing will not be a limiting factor. "Posture" can also easily be made into an almost non issue, by removing spacers and/or flipping your stem. Doing this will put you in the same position as most drop bar riders with their hands on the hoods, which is where most spend most of their time anyway. Unless they use the drops, they are in no more of an aerodynamic position than someone with properly set mountain bars.

plutonium83

I remember the first day I put on slicks on my MTB commuter, I fell in love and bought a hybrid roadie 6 months later.

electrik

nowhere near as fast, the road bike's advantage is not the tires but the aerodynamic positioning of the rider.

agarose2000

I doubt a typical mtn bike gearing has enough gears to go 21+mph, let alone 25+.

wunderkind

Must be referring to hybrids with curve handlebars...

no1mad 

Or the lack of rack/fender mounts?

tatfiend 

Most MTBs have a high gear of about 104 gear inches with a high gear of 11/44, figuring 26" O.D. tires. At a cadence of 100 this is over 30 MPH in high gear. The speed limitation is more air resistance and rolling resistance than gearing.

With road slicks on the MTB the wheel diameter might be closer to 24.5" but that is still a 98" high gear and 29 MPH at a cadence of 100 or 23+ MPH at a cadence of 80. A cadence of 80 should be obtainable by virtually any cyclist and a cadence of 100 is readily obtainable with a bit of practice.

MK313

Agree with the above posts, it won't be as fast as a road bike, but it will make a big difference in your commute. I used to ride a mountain bike to work & can still remember when I wore out my original tires & switched to slicks, it was like Christmas. If the Trek 800 is going to remain your main commuter, there are few things that will make as big of a difference in speed/$ as adding slicks.

nashvillwill

I'll let you know tomorrow. I have a Schwinn MTB (2000 Frontier). Over the long weekend, i switched from 26x1.95 knobbies to 26x1.25 slicks. On tomorrow's commute i fully expect an enjoyable experience. It's a heavy bike, with mountain gearing, so i'll have to get back to you. Also, i went from 45 psi on the old tires to 80 psi on the new (psi range is 65-100 so i might experiment).

For the record, i'm not really looking to add speed, just hoping for an easier ride when it comes to resistance.

P.S.-First post!

dokterd1

Thanks for all the replies. I do not want to commute on my road bike because leaving it locked to a rack for an extended period of time is not something I am comfortable with.
Any suggestions on tires? I have heard that its a mistake to cheap out on tires.

aley

The gearing differences between my MTB and my road bike account for a lot of the speed difference for me. On my road bike, I have a close ratio cassette (12-24 9-speed, so it's something like 12-13-14-15-16-17-19-21-24), and on my MTB I have a wide ratio cassette (11-34 9-speed). The road bike has just the right gear for pretty much any speed I care to go, so I can keep my cadence in the mid-90s, or if I'm feeling feisty dial it into the upper 90s, and go whatever speed gives my legs the workload they're comfortable with. On the MTB, there are huge gaps between gears, and often I'll find myself going slower than I want because I can't spin fast enough in the gear I'm in to go the speed I'd like, and if I upshift I'm spinning too slowly to be comfortable. I end up hunting between gears, and eventually slowing down a bit to keep my cadence in my comfort zone.

tjspiel

Not sure I understand what you're saying. Lots of road bikes have rack and fender mounts. High end racing bikes typically don't but they're only a subset of all road bikes. Between my wife and I we've owned 4 different road bikes in the last few years and everyone of them has had rack and fender mounts including my Specialized Allez (though that only has rack mounts).

Sixty Fiver

103 gear inches on mine...

mustang1

On a commute, where you're not bombing from one set of traffic lights to the next, and in rush hour traffic, I'm guessing your speed will be pretty similar to a road bike. Ultimately, rb will be faster due to it's more aggressive geo but for a commute, doubt it'd make a bunch of difference.