Drag bike

[highspeedcycle]

I was just thinking, what could I do to convert a wal-mart mtn bike into a bike to be used to go from 0-20mph really fast. lol i know it sounds stupid but i wanna try to do it.

What should i add/remove? I know the front gears and deraillaur(spell check) lol

What kinda tires and wheels?

anything else?

thanks
http://www.NickReynolds.net

[Brian]

Depends on how strong your legs are, and how fast you want to spin. Someone should come to your rescue with the math for the gearing. In the meantime, you will want to remove an excess weight.

It is not our place to ask why, only to help you achieve your goal, as dubious as it may seem. :D

[Stacey]

You might want to look in to energy storing mass such as a flywheel. Spin the flywheel up, engage the rear dirve and off you go.


Don't forget to hang on!

[Rincewind8]

I was just thinking, what could I do to convert a wal-mart mtn bike into a bike to be used to go from 0-20mph really fast. lol i know it sounds stupid but i wanna try to do it.

What should i add/remove? I know the front gears and deraillaur(spell check) lol

What kinda tires and wheels?

anything else?

thanks
http://www.NickReynolds.net
I don't know what exactly you want to do. Do you want to just want to go from 0-20mph and then stop or do you want to keep going at 20mph. What kind of surface are you planning to do that on, closed parking lot with smooth pavement or bike trail or...? In general, to make a bike accelerate fast, get fairly narrow high pressure tires and small diameter wheels. Possibly just one gear and possibly the gear range, so that you just not spin out at the highest speed you want to reach. There is a pretty good gear calculator here:
http://sheldonbrown.com/gears/

[Sir Lunch-a-lot]

Maybe add on some sort of a fairing to cut down on wind resistance.

[wearyourtruth]

find a steep hill ;)

[jeff-o]

get two very large, industrial-sized elastic bands......

[biodiesel]

You need one of these.

An xtracycle without racks. You can't possibly wheelie this thing and will almost never endo. On a rig like this you look like a drag racer. Then you just need a can of NOS.

[Eatadonut]

for the gearing, I would use probably a 34-25. That's the granny gear on my roadie, and if I remember correctly it gets to 20.4 mph at about 150 rpm, and I can spin it up pretty quickly.

I'm liking the flywheel idea. How do you rig up a clutch for your bike, though? Think about the usefulness in traffic situations. No more angry drivers when a red light goes green and you're working to get to speed.

[highspeedcycle]

FLYWHEEL, omg, why did i not think of that. i love it.

Lets work on this now!... What parts should i start with and whats the basic design, i love it.

thanks
Nick

[Stacey]

Gee, all I have is concept, and that's free. You want design? That's $250 an hour :D

Seriously. I'm thinking of the flywheel from an old Schwinn Excersize bike. Drive it from one of the sprockets on one of those old Front Feewheel systems Schwinn used on their gaspipe lightweights. Use the other sprocket to drive the rear wheel. With the bike up on a drop stand (back wheel up while you get the mass up to speed)you crank the snot out of it, the ffs will let the rotational mass spin without the cranks beating the crap out of your legs. Just a starting point. :)

[Brian]

Flywheel? Chainguard. When that chain snaps, it's going to be dangerous.

[Eatadonut]

why would the chain be any more likely to snap than a normal chain, also, why would it be more dangerous?

[Brian]

With a flywheel? Stored energy + bike chain = accident.

[Eatadonut]

...much like dropping the clutch at 8k rpm in a truck. I gotcha. That's why you gotta keep the chain spinning as you release the clutch.

Also, remember that there's no way you'll be applying more force to the chain this way than a fixie would skidding.

[MnHPVA Guy]

Also, remember that there's no way you'll be applying more force to the chain this way than a fixie would skidding.How so? Weight transfers off the rear wheel on decelleration and onto it on accelleration.

Regarding gearing for drag racing to 20 mph;
Most of the recommendations have been for a single gear.
I entered a double elimination 50 meter drag race a couple of years back at an HPV event. Most of the 12 other racers used one or 2 gears. I used 155mm cranks, a 34t chainring and 5 gears in the rear, shifting every couple of seconds. I think the cogs were 24-21-18-16-14. I never stood on the pedals, just sat and spun.

None of the runs were even close. I was always able to ease up before the finish to conserve energy for the next run. I needed to because at 57 years old I was at least twice the age of the average competitor.

"Old age and treachery always overcome youth and strength"

[highspeedcycle]

did you beat everyone?

[Brian]

Of course he did, he's old and treacherous.

[Hal Hardy]

You might want to look in to energy storing mass such as a flywheel. Spin the flywheel up, engage the rear dirve and off you go.


A low racer recumbent would be a good platform. The link has an extreme example. It's the third bike down. I wonder if anyone's learned to ride it yet?

http://www.dclxvi.org/chunk/meet/outside/index.html

[cranky]

How about a Trebuchet Bike? Using the same principle of storing energy into a flywheel, only you put it into a weight. Pedaling in a low gear with pulleys lifts a heavy weight, release the weight to propel the bike.

[icithecat]

Then you just need a can of NOS.
Or a chilli burritto. :eek:

[Eatadonut]

How so? Weight transfers off the rear wheel on decelleration and onto it on accelleration.



True. Obvious solution: someone try it, and we want pics!

[Stacey]

A low racer recumbent would be a good platform. The link has an extreme example. It's the third bike down. I wonder if anyone's learned to ride it yet?

http://www.dclxvi.org/chunk/meet/outside/index.html


That's exactly what I'm talking about.

[duckliondog]

You need to be able to put all your energy into the rear wheel. Including arm power. (http://www.bodybike.org/home.htm)

[2manybikes]

You mean a bicycle that is a dragster ??