45mph bike under 2000usd?

[cwah]

Hello,

I have a friend of mine who wants an electric bike that runs at 45mph and do 15 miles distance for about 2000usd budget.... all included.

He doesn't have a bike yet.

That does seem quite a stretch in term of budget. He wants to get a cheap montain bike but I'm not sure it's going to work out.

Any idea what's the best way to have what he wants?

 

[MadRhino]

You can start with a pretty good bike if you check the adds on Pinkbike in the coming month. I'd say 500$ for an old Specialized Big Hit for an example, then another 1000$ for a good motor and controller, and 500$ of RC Lipo. See, with this low budget you can build a powerful bike that will ride safe and fine. Of course there will be some extra money to spend on charger and misc. hardware, but you can cut a lot on the price of motor-controller combo if the budget is really tight.

 

[ambroseliao]

Any idea what's the best way to have what he wants?

http://goo.gl/l5SGjY :wink:

2 out of 3 ain't bad.

 

[cwah]

Which motor/controller combo to get?

And no, no bomber it's way out of budget

 

[sacko]

24s lipo
Crystalyte 4065
18fet controller
Specialized Big Hit

 

[Hillhater]

At 45 mph he isnt going to be pedaling, so to keep that speed ( on the flat) he would need 3kw approx. ( more to accelerate up to speed & hills )
So if his 15 miles takes 20 mins ( say 30 for stop/starts etc),.. he will need at least 1.5 kWhr of battery ( better 2kWhr in reality ! )
I think that will be half the budget on battery alone.
Maybe he should rethink his speed requirement ?
30 -35 mph would only require half that power & battery

 

[amberwolf]

Any idea what's the best way to have what he wants?

http://www.endless-sphere.com/w/index.php/I%27m_a_Noob_and_I_Wanna_Go_50MPH

 

[mvly]

I would say it is not possible.

If he wants to do 45mph continuously, then he would need around 2KWh like other members are saying to do it comfortably given how lilo voltage goes down as you drain it.

Even 2KWh lipo is expensive. Not taking into account mounting process.

The only motor that can do it comfortably would be the TC-80/TC-100, x54, or the cromotor. There are middrive that can do it for less wattage, but to sustain 45mph is the difficult part.

Also can a bike frame safely handle the stress of day to day rides.

Finally, he would definitely need to run 74V minimum. Most likely 88V or more would be better.

Then you ate looking at a hefty price on a reliable controller to handle that voltage and power.

My calculation on my setup that can comfortably sustain 45mph:

TC-80- $800
Kelly controller- $600
88V30ah limn- $700
Mountain bike- $500

And this is not counting all the misc stuff such as wires, connectors, CA, etc.

Even if he finds these parts used, it will still be more than $2K IMO.

 

[wesnewell]

http://endless-sphere.com/forums/viewtopic.php?f=2&t=53119
For 15 miles@45mph you'll need about 1kwh of battery. About $450 using 20c 4s hard case packs as 24s3p for 1.33kwh.

 

[Geebee]

A couple of ways to lower power requirement at speed would be a road bike and ride in a tuck at speed, or a recumbent bike and ride in comfort.

 

[cwah]

Guys,

What about this configuration?
http://www.bmsbattery.com/controller/607-s06-250w-imitation-torque-square-wave-controller.html
http://www.bmsbattery.com/ebike-kits/529-q11-48v1kw-front-driving-hub-motor-e-bike-conversion-kit.html
http://www.bmsbattery.com/ebike-kits/528-q11-48v1kw-front-driving-hub-motor-e-bike-conversion-kit.html

Dual Q11 + Dual controller = 700USD shipped. Probably 800USD total with customs?

For the bike... not sure which one yet. (I'm located in France)

 

[dogman dan]

That could work. two of any cheaper dd hubmotor gets you 2000w per motor, so it would not melt in 10 miles like one would.

But at 72v, the winding might limit speed closer to 40 mph. 40 is plenty, tell him to build for 40 mph, at least at first. Try one motor first with a 40 amps controller, then add the second if truly not satisfied.

A pretty strong bike is needed, with good brakes. It could be a cheap used one as long as it has a very stiff frame and v brakes or disk, but a big hit or equivalent will be better.

When I built a bike that went 47 mph for a shorter distance, I went with 100v to get that speed. But the cheaper motors could not hack that for very long at all. Mo bettah build 72v and have 40 mph.

 

[cwah]

Yeah I'm trying to see if they have 2*36V model so it would be able to reach the required speed.

Currently on their website they only have the front and rear 48V which may only be good to 40mph...


What motor did you use for 47mph?

Cromotor seem to be difficult to get a hand on in europe I think

 

[dogman dan]

I did that with a cheap muxux, 2807 or 9x7 winding. On 26s. But again, it was getting way too hot immediately at that voltage and 40 amps. At 72v 40 amps, you could get a reliable 8-10 miles before it would be melty hot. You'd hit 40 mph briefly, and then cruise out the ride at about 37 mph.

But two motors with 100v and 30 amps, each one should only be pulling a very reasonable 20 amps each to be hauling ass. 2000w each, it should work with even the cheapest motors and last the 15 miles. How you carry enough battery beats me. I'd call it close to impossible as the power needed goes exponential as you speed up. 4000w continuous means you carry about 2kw total for that distance. That's huge even for lipo, and battery alone + charging will cost a bundle even if you figure out a way to carry it all that doesn't suck.

You gotta build a honking good torque arm to run 2000w or more on front forks. I welded tabs to my steel fork for a bolt on TA. No way you can run hose clamp torque arms at that power level.

Build for 35 mph, 40 mph max. It will cost about half what 45 mph, 50 max will cost.

 

[speedmd]

"Build for 35 mph, 40 mph max. It will cost about half what 45 mph, 50 max will cost."

+1 on that. Add the benefits of not getting hauled over and it will save tons of headaches for a commuter. 1200 -$1500 realistic for a reliable 35mph build. Add $1000 min for the faster heavier build. Plus motorcycle reg and insurance issues once you get caught.

 

[cwah]

Yeah I tried to advise him on that and recommanded him 30mph max speed for decent cost.

But he does some motorbike and that's why he wants something with closer performance...

 

[dogman dan]

I just think you will end up over 2k because of the battery + charging system costs if you build for a 45 mph cruise of that distance. A bike I would ride for that distance at 45 mph, on regular rough streets, would retail in the $1000-$2000 price range new. Even used, $800 for a decent bike is likely. One of the main problems is simply how to carry enough battery to go that far. Oh sure, you can strap it on, but is it still rideable at 45 mph after that? Likely not!!!!

He needs to get a reality check, either on the speed or the money. But 55 kph is pretty easy, especially if you can dig up an old 5304 motor someplace.

Tell him to build for slower now, or get the money for the newer frames that can carry serious battery, and a cromotor or something with an wide stator. Maybe even do a John in CR style build. Check out his cannondale, with the scooter motor in a custom swing arm. I think he still has the motors for sale.

45 mph cruise, I'd be looking at motorcycle or scooter frames to convert. By the time you get the motorcycle rims and tires on your bike, there you are. But your frame is just to weak.

 

[MadRhino]

Well, building a bike that can ride 45 Mph does not mean it will be doing that top speed continuously. Most likely it will ride about 80 % of its top speed half of the time, and the other half sometimes very slow, sometimes WOT.

You have to build the bike for the speed that you will ride. If riding 45 Mph continuously, it has to be capable of 55 and that is a very different budget.

 

[dogman dan]

Perhaps I misunderstand, I read 45 mph and 15 miles distance. To me that meant 15 miles at 40 mph at least. That's assuming you get 45 mph at top of charge, but lots of the ride is up to 5 mph slower. Too far for the budget 40 mph build with the cheap motors to pull that distance without melting. Can be done by vented 5304 perhaps. Or, as discussed, two cheap motors. Not sure I wouldn't just prefer one big motor though.

Change that expectation to just hits 40 mph, and able to cruise 32 mph for 15 miles, and it's a lot easier and more affordable. 10 mph less for the 15 mile run takes a shitload less battery. Now you have a chance with regular bike tires and rims, and carrying the battery is quite possible even on some pretty cheap bikes. Look at Wes for how to do those criteria on the cheap.

I just found that 5 mph more than 40 was really costly. But hits 40 and cruises 30-35 is quite cheap and easy.

 

[cal3thousand]

My bike is costing well over $2000 and I put A LOT of time into saving money (used frame/fork). Even built my own wheels and made my own pack with LiPos. It's only going to do 43mph at the top with 35mph being the norm. To get the bike in the category that you are asking would require at least $1000 more (IMO) to be safe. That would include a $300 brake upgrade, and a Crown motor and selling my HT3525 just to make the difference.

$3500 to do it comfortably and safely. $2000 is just about possible, but that $1500 savings might cost you elsewhere.

 

[wesnewell]

Get a Cycle Analyst and a Multimeter, you're still a noob if you don't have at least one of each.

Guess I'll always be a noob then as I have no desire or need for a CA with over 10,000 miles without one.
My bike cost under $700 if you don't count the seat. new wheels, and windshield. It'll do 40+ mph on 10ah 24s lipo. I could pretty much guarantee 45mph for 15 miles for under $2000. All I would need would be a bigger (or dual) motor and another 5ah of 24s.

 

[jimw1960]

It might be cheaper to find a used motorcycle with a blown motor and convert it. A bicycle properly equipped to go 45 mph will cost over $1,000 after you upgrade brakes and suspension. I see good motorcycles with blown engines on craigslist all the time for $500 to 1,000.

 

[jansevr]

if youre talking about getting a crown...you might as well just get a cro motor...

sure it'll be a better/ safer bike with another $1000 but a $2000 budget is a pretty fair place to start. also $300 for brakes sounds pretty pricey...ive always had great braking power with my avid bb7s and they were only $100 for the set (and $50 for 230mm rotors). usually a good downhill bike will have decent brakes already. i agree with what a lot of other people have been saying...45mph top speed but a more realistic cruising speed is 30-35. not only will it be more efficient/use less power for the distance its also safer and cheaper to build. i guess it might depending on where you live/the roads you travel but to me, 45mph cruising sounds fast.

this is what i would recommend (some of which has already been pointed out):

$500 for a used downhill bike
$500 for 4s turnigy hardcase
$300 crystalyte hs3540
$120 cycle analyst
$120 24fet greentime controller http://www.aliexpress.com/store/pro...oller-sensor-sensorless/313864_522263950.html
$210 (2x Hyperion EOS 1420i 550w = 1100w total) http://www.amazon.com/Hyperion-EOS-1420i-Net3-Charger/dp/B004E7MQ3Y
$65 power supply http://www.ebay.com/itm/261329043167

with that charging setup it would take just over an hour to charger a pack slightly larger than 1kwh - not bad!

that leaves about $185 for misc. parts/hardware/wiring...or more money to spend on a bike.

depending on your climate it would probably be in your best interest to drill cooling holes in the motor but as long as your total load is under 300lbs you should be able to manage 35mph continuous for your 15 miles. investing in a large chainring like so you can pedal at 30-35mph would also be a good idea so you can still provide some input to save battery power (and so it still looks like a bike :lol: )

 

[cwah]

It does feel like motor like the crown are overpriced... for now, the double Q11 seems to be the most abordable??

For the motorcycle conversion it might take too much effort to do that? A good DH bike should be about the same price I suppose?

Jansevr, I'm not sure the HS3540 is up for the job. Checking ebike.ca/simulator, at 45mph constant it burns under 10 mn :lol:

My friend does really not have any clue about ebike, so if I have to tell him to be careful about lipo then not using top speed for long etc... I'm not sure he'll be disciplined enough to not burn either the motor or kill the batteries.

 

[jansevr]

like i said, 45mph seems a bit fast...the hs3540 could do 30-35 for that distance. also i dont think the simulator takes into account air cooling if you were to drill holes (which should help a bit). if you really want 45mph continuous speed then i would say you NEED a cro motor. so add $300...with the other parts i recommended thats only like $100 over budget. its pretty much the best hub available and motors like crystalyte can't even compare.