Ross520

Hi guys,

So, I'm not exactly sure how the topic was broached, but myself, and a buddy of mine ended up getting into a friendly argument yesterday over which one would win in a short sprint (eighth or quarter mile). He's adamant that he would be able to beat me on his BMX bike, however, I don't agree with that assertion.

I believe that he would pull off the line quicker due to having smaller wheels (not sure what sprocket or cassette he's running), but that it wouldn't be long before I pulled on him.

I think key would be making sure I start off in the correct gear. The only way I foresee myself losing would be user error.

BTW, we have placed a small wager of $40 on the race.

So, what does everyone else think?

Elvo

Whoever is in better sprinting shape

aclinjury

in my books, "sprinting" is anything 300m or less. Quarter-mile is pretty damn long to be sprinting all out.

Having said that, I think you buddy will beat you in anything less than 200m. Many BMX racers can generate very good anaerobic power, we're talking 1500-1800w. Your buddy may not be a true bmx racer, but he'll have good power, so I wouldn't under estimate him if it's 200m or less.

Ross520

That would be me. Between the long hours he works, and his wife and kids, I don't think he rides much anymore.

Out of curiosity, all things being equal conditioning-wise, which bike do you believe has been the advantage?

Ross520

He's a bit out-of-practice, but he was quite fast years ago. And wow, that's pretty serious power.

burnthesheep

Yup, lots of bmx racers can sprint a lot better than generic roadies. All about that hole-shot.

If it's actually 1/8th or a 1/4... push for it to be the 1/4....your buddy is toast if you aren't a total Fred. That's simply too far for a bmx bike's gearing to work out.

An 1/8 mile is 300 meters. So, you may be toast if it is 1/8 mile or less.

Video please. Results please, with data. Give your boy a spare gps to throw in his pocket also.

Also, consider a double-nothing bet on swapping bikes for a second race. If you trust each other and have similar shoe sizes.

msu2001la

I don't know that much about BMX bikes, but according to google if they're set up for racing, they run gears in the neighborhood of 46t up front and 16t in the rear.
Assuming it's a 20" BMX bike, at 130rpm cadence that's just a little over 20mph max speed on a flat road.

I get that BMX bikes are fast off the line, but over 1/8 or 1/4 mile that advantage disappears pretty quickly. Unless I'm missing something, it should be pretty easy to take his $40. I doubt you'd even have to sprint very hard.

pickettt

Specifics are everything; it can be swayed either way by just tweaking any one factor. I’ve raced most disciplines of cycling, and I would say in 1/8 mile or less, I would be faster on a BMX bike than myself on a road bike.

Wilfred Laurier

I used to commute to work with a chum who rode his BMX bike while I rode my road bike. He was stronger than me, and he was faster than me.

If the two riders are of similar strength and fitness, I would give the edge to the road bike for anything over ~200 m. The riding position of aa BMX doesn't lend itself to cranking out power for any length of time, unless the rider is a training fanatic.

subgrade

1/8 mile is 201 meters actually, and I agree that over that distance BMX might win. It's not just about gearing and wheel size, but also frame and handlebar geometry which in case of a BMX bike is better suited to standing starts.

surak

This reminds me of an evening commute last year where I rode into a bmx vs road bike race. I already had 14 miles under my tires at the point where I rang my bell to indicate that I wanted to pass a group of teenage bmx riders noodling around the MUP. One decided to take off sprinting. I caught up in less than 10 seconds and blew by him. Granted, I wasn't starting from standstill, but I don't think a bmx has a chance once its speed tops out.

Edit to add: I think I probably caught up in about 5 seconds, and I didn't get out of the saddle to sprint either, just spun up to pass him nonchalantly.

Loose Chain

I do not know but I usually pass BMX bikes like they are dragging an anchor, even on my commuter converted Rock Hopper. If I am on a road racing bike with a decent spread of gearing I would smoke him no matter how many Watts he puts out. The little teeny, weenie wheels can only go so fast on a fixie/SS BMX. But the I do not know part is passing up teeny boppers on a BMX might not be a good test of a strong adult rider. Most strong roadies can push 30 MPH and 25 miles in one hour is kind of a bench mark for some. Is there any reports of a BMXer covering 25 miles in one hour? I think it more likely he will boink out at about 16 MPH and you will catch him about or just before the 1/8 mile finish doing about 22 MPH. And from there on out it would be a fool's match for him.

burnthesheep

I say you take on Shirtless Keith:

ljsense

I agree with everyone who pointed out the huge difference here between quarter mile and an eighth mile. 100 percent difference.

Will you start with one foot on the ground and struggle to clip in while he's standing on his platforms like he's up against the gate?

Also, what's the course like? I'm assuming flat and straight, but who knows? It could have a jump or something, or a flight of downhill stairs with a rail to grind on. But even just a normal uphill would take away advantage from the road bike, since it will help him avoid running out of his gear.

You've got to hit 30+ mph and have enough track left for that to put you ahead.

If he shows up with a small brown gremlin like creature in his milk cart front basket, you're toast.

Rajflyboy

Pro level BMX riders are going as fast as 45 MPH to clear the first double off the start ramp (they pedal to the launch point).

Those boys and and girls are bad ass riders.

pickettt

I was a Pro XC MTB racer, and I’d bet against myself vs. a pro BMX racer over 1/8 mile.

Ross520

Thanks for all of the replies, folks!

As far as the distance is concerned, we have now agreed on an eighth. Both of us felt that a quarter would favor me too much, as many of you mentioned earlier.

As far as pedals are concerned, I'm not sure. I tried clipping-in quickly on my ride yesterday, and while I didn't miss the clip, I still found myself wondering if throwing the flats that came with the bike (sans toe clips) on might be a good idea. His only chance is getting me is off the dig, so I doubt he will agree to a rolling start or letting me lean against something. We shall see...

The course will be a straight, flat stretch of road.

Regarding his fitness, at one time, he had excellent conditioning, but I don't believe he rides much anymore. Definitely not pro or even amateur BMX racing level. I'm pretty new to road cycling, but had a decent level of fitness before hand from kickboxing and weight-lifting. He will definitely be a lot lighter though, as I'm 6' 3", 200lbs.


Also, that "Shirtless Keith" fella looks pretty quick. I wouldn't like my chances against him 😜.

I'll try to get this done this week, and will post video, as well as GPS, as one member requested.

Updates to follow...

bakerjw

Running the math.
With a 20" tire and 46/16 gearing, a BMX at 130 cadence would give about 22.25 mph.
With a 29" tire and 34/17 gearing, a road bike at 130 cadence would give about 22.4 mph. (the compact chain ring on my road bike is 34T)

Of course crank arm length doesn't come into play and I have virtually no knowledge of BMX bike so I cannot make any call on that.
With crank lengths being equal and the road bike set 34 in the front and 17 in the rear, the cadence/speed is almost identical.

With flat pedals on the road bike removing the clipping in delay, I'd have to give the edge to the road bike.

With the crank arm length taken into account, I am certain that there is a road bike ratio that would match the (Torque In)/(Torque Out) ratio.

Caliper

Except that by 130rpm, most riders power is falling off, a road bike could start at a 34/19 to get better torque at the start and then just move through the cassette up to a 30mph+ terminal speed, while the BMX tops out at 22-25mph. Given fairly equally matched riders, I'm backing the road bike for the win.


If this is a full standing start, I would still opt for SPD pedals over flats to give better foot control and position. If you can go from an extremely slow roll/trackstand, then road cleats.

subgrade

You did not take into account that the wider handlebars ona BMX lend a better counterbalance (counter torque) when pushing hard on the pedals, thus the rider is able to put down more torque.

aclinjury

I want to see an as "fair and square" match as possible, so here's my suggestions:

1. to eliminate your slow clipping in, both of you start from a track stand (while you're clipped in). You only need to track stand for 1 second.
2. do not pick a distance where gearing comes into play! It's a wussy way to win if the other bloke runs out of gears.

Ultimately, this is a sprint contest, so own up to it and allow it to be a sprinting contest. Nobody cares about BMX and endurance, we want to see balls out sprinting.

ljsense

Go get 'em. Should be a race -- looking forward to seeing the results.

Are we supposed to make bets?

Rajflyboy

BMX racers clip in now a days

Rajflyboy

This

Loose Chain

No, not this. The OP was a road bike vs a BMX and most BMX are single speed and most road bikes are geared. I do not see why the road bike fellow would have to give up a major advantage. But, that said, I will bet a fixie or SS over a BMX still. I would rather see two equal sprinters on the two very different bicycle types.