Crystalyte 5303 72v+ EV? (Looking for speed!)

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Cowled_Wolfe
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Crystalyte 5303 72v+ EV? (Looking for speed!)

Howdy there. I'm looking to scratch-build a non-pedal EV, but I'm posting it here because I'm looking to use a Crystalite 5303 Racer hub on a 26" bike wheel for the drive system.

I've got a few questions about performance, but first I'll post my general design info to give ya'll a picture of what I'd like to be running.

First of all, the frame will be a home-made carbon fiber/foam/aluminum construction. There will be a swing arm rear suspension assembly made of carbon, but with lots of steel (I intend to build in some very strong mounting points for an overbuilt motor torque arm -- this will be rear wheel drive). The front fork will be a downhill racer type with in-fork suspension. The frame/body is to be of a feet-first/seated design and will feature aerodynamic fairings (fiberglass) to improve efficiency and improve the experience of riding in wet weather. I'd like to use 26" wheels front and rear.

A front disk brake is a must. :)

Estimated frame weight is around 20-30LBS with fairings, seat, etc. Total vehicle weight (with batteries and motor) is estimated at 80-100lbs. Rider is 210lbs, but is trying to reduce that to around 180. ;)

If I go through with this, it will be equipped with proper lighting and mirrors, then inspected by the State Patrol so I can register as a motorcycle.

... Questions:

1.) What top speed might I expect with a 72v system driven by two 37v 10AH LiPo packs in series? I'd like to keep up with 55-60MPH traffic for roughly 5-10 miles. My commute is on level ground with moderate winds.

2.) What would I be able to expect using 4x 25.9V packs in series? (Assuming I upgrade my controller to handle it.)

3.) Am I an idiot to even attempt this? Would I be better off using some other drive system?

Cowled_Wolfe
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Re: Crystalyte 5303 72v+ EV? (Looking for speed!)

I forgot to mention... I'd like to use a "front" wheel in the rear. I won't have pedals, so I don't need any provisons on the wheel for gears/freehubs. I'll be making the rear swing arm, so the narrower width is not an issue.

dogman
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Re: Crystalyte 5303 72v+ EV? (Looking for speed!)

Good idea on the no peadles. It would be funny to see you trying to peadle at 50 mph. But I don't want to see your crash on youtube. Use some motorcycle stuff to look for speed. There is a big difference between hitting 50 on an short downhill ride and sustained 50 mph speeds on shitty roads. One good pothole or half a semi tire in your lane and you are dead. On top of that, the cars will never see you when they kill you if the thing is low slung like a recumbent. Basicly bike rims and tires are simply not made for the kind of use you describe. Motorcycle stuff is, so use those rims and tires and just power em with a chain drive motor. The bike idea is cool, but not on regular streets. Keep that for a dry lake or racetrack and lotsa leathers.

Be the pack leader.
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swbluto
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Re: Crystalyte 5303 72v+ EV? (Looking for speed!)

I have to agree with dogman.

The amount of energy you need to dissipate through the disc brakes is the square of velocity; Since those disc-brakes are designed for an equivalent of 30-40 mph(50 mph downhill is not even comparable since the traction is definitely not as great as asphalt), stopping at 60mph would dissipate 4 times the amount of kinetic energy than a bike at 30 mph and the extra weight would also increase your bike's kinetic energy by about 1.3 times, so you're looking at 5.2 times the amount of kinetic energy you'd need to dissipate, which bicycle disc brakes are not designed for. Have you seen how burly those motorcycle disc brakes are? The extra mass(and area) is needed to dissipate the heat effectively enough so disc fade doesn't become an issue and you don't want your brakes fading in an emergency stopping scenario!

Also, you want dual suspension with plenty of travel and a frame that can absorb the impact of a pot-hole at 60 mph. As far as I know, no bicycle that I know of meets those requirements. You're far safer modifying a frame designed for the extra speed. Look at motorcycles.

(I've hit "bumpy roads" at 28 mph on a hardtail and... stability went out the window as the back kept jumping around(I didn't crash, though!). I can't imagine what would happen at 50.)

Cowled_Wolfe
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Re: Crystalyte 5303 72v+ EV? (Looking for speed!)

Thanks for the responses. I've decided that for the moment, I'll shelve this project until I can do a full-scale, motorcycle based platform.

For now, I've changed my goals to an E-bike which looks normal enough for me to place on our local bus system's bike racks... 35+MPH @ zero amps, mwahahaha... :)

Cheers,
Wolfe.

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