renaldo

Is a BMX faster than a Mountain bike over 100meter

grubetown

Interesting question

JonathanGennick 

I'm going to edit my response to say that the answer probably comes down to specific bikes and rider. I don't think it's possible to generalize. There are so many variables: flat ground versus rollers, gearing on the BMX bike, quality and weight of components and frames, tire choices, and I think in the end the answer is always going to come down to what a specific rider can do given two bikes to play with. Change up the bikes or the rider, and you'll get a different result.

OldsCOOL

If you are the only variable, my money is on the mountain bike due to the multiple gearing.
I know if it were asked of me which I am faster of the two, I’m grabbing the MTB and hammering out the 100m sprint.

renaldo

Why would the BMX go faster or why would the MTB go faster, reasons pls....

FBinNY 

It really depends on the gearing and engine. A BMX bike will be lighter (usually) meaning faster acceleration off the line, and if the rider has enough top end RPMs, that advantage may carry for 100m. Of course, with greater distance, being able to shift to a higher gear settles the issue.

fietsbob

Out of the gate, like at the Olympics, Moto Cross bicycle races.. Moto also being the name for each round of elimination,

the Light, specialty bikes for those events will have pretty light wheels , Not to be confused, they dont see the abuse of X games type half pipe Stunt events ,

and so those little wheels accelerate quickly.. as you may have seen the races are like sprints over an undulating course with corners.. they're over very quickly

In the 80s there was classic technology applied to the track racing moto-cross.. Sew Up Tires glued to special 20" rims (like 451 rim size)..

tread like the larger Cyclo-cross racing patterns..

fietsbob

whole course (UCI length between 300-400m) in a little over 37.5 seconds

LesterOfPuppets

As I mentioned in other thread, I'd go with MTB assuming SS BMX and multispeed MTB from a standing start. 100m is a long ways to go in one gear, starting from a dead stop.

For the MTB, pick something rigid and light. Take something like this 15 lb hardtail and put a rigid fork on it.



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Win!

JonathanGennick 

BMX racers are _fast_ in one gear. The ones I know, it would slow them down to be shifting in the first 100 meters.

I don't think the question as stated can be answered. Too many variables. Impossible to generalize.

LesterOfPuppets

Yep, I think BMXer or SSMTBer would be hindered by the standing start. If a rolling start, then they could choose a higher GI and get in their zone before start line and keep it for all 100 meters.

Even the best SS rider is gonna be hurt by having either too high a gear to get a good start or too low a gear to finish well.

Also the MTBer would need some test runs to determine best launch gear and how many times to shift. I would guess two shifts tops. It would probably be advantageous to make a custom cassette with a 20% jump between launch gear and finish gear, then only do one shift. Typical shimano cassettes these days have 12-14% jumps and that would encourage too much shifting, I'd imagine.

A downhill start gate would help the SS rider, but I'm just assuming a 100m flat run. On a football/soccer field, perhaps.

I reckon in a race between one pro BMXer on SS and one pro BMXer on 2-speed, the 2-speed guy would win.

SS guy might have a chance up to 60 meters or so.

pickettt

At 100 meters, BMXer all day everyday. Increase the distance and the odds go toward an MTBer. I've raced both extensively.

LesterOfPuppets

I should go down the soccer field with my rigid dirt jumper and HT MTB, and see what I'm faster on.

If I put some lighter tires on the DJ, they would both be 25 lbs, so even-steven there.

I've gotta pull the 18 cog and get the 16 back on there to have a chance on it, though.

I'm pretty good at spinning from riding fixies downhill, so might be a semi fair fight.