I need some advice on upgrading from 1000w 48v

[chris-b]

Hi guys,

This is my whistle miwok 1384d. I'm currently running a 48v 1000w cheapy Chinese kit that after 700 miles of abuse I'm still very happy with. Well, apart from when I'm on a long straight! 30mph just isn't enough! Behind mine is my friends denzel gross 3000w 72v bike. Unfortunately he won't sell me his motor and battery, and I'm pretty sure he would notice if I swapped them over when he wasn't looking.

So my question is, what would you recommend to increase my top end to at least 45mph? And what kind of battery will I need? I really want to keep it within the triangle part of my frame. I'm not too worried about massive range, 20 miles will do. I'm looking for the cheapest way possible as I only use it to go to work and back and the odd short journey when it's not bloody raining here in the UK.

Thanks!!!!

 

[dogman dan]

You can put a 72v 40 amps controller on that motor, but the catch 22 is that after 10 miles of full speed riding you will be about to melt it.

You need 20 miles? At 40 mph that is a battery that won't fit in your triangle. But if you need 10 miles, you can get er done with some RC lipo, and a good triangle bag from EM3ev.

So if you can ride 10 miles, then cool the motor while you charge a few hours, then do the other 10, you can go with 72v 10 ah lipo pretty cheap. But more than that, you'll be in melt your motor territory.

 

[wesnewell]

If you truly want 45 mph, you'll probably need to go to 24s lipo (that's what I run mine on), but like DM says, you can't run that motor much over 30 mph continuously. And 45 mph takes ~80wh per mile while 30 mph only takes ~40wh per mile.

 

[999zip999]

Think 35mph with that frame. A 1,500 leaf motor 4t and 72v 20ah triangle battery em3ev.First make a box out of cardboard for mock up to see if it fits. Then a 40amp controller sinewave is the way to go.
What type of terrain ? How tou weigh ?
Or just use that unlocked bike behind you.

 

[chris-b]

Thanks for all of your replies!

I'd really prefer not to run any more power through the motor that's on there, it starts to whine even in a strong headwind (and knocking off a valuable 10mph!). I'd also really like to keep it 'stealthy' hence keeping the frame I've got. Handling is also a priority as I'm throwing it about a lot when I'm on it. I'm about 80kg and the bike before I put any electrics on it was 16kg. Terrain consists of mainly road with bits of soft off road, jumping up and down kerbs etc...

I think the next step is to mock up a cardboard cutout of my triangle (it's quite big, 21' frame) and see if an aliexpress battery seller can knock me something up that will fit. Although I am now aware that I'm going to need twice the battery capacity to go the same distance at 15mph faster (that right?). I think it will be alright as I only use 1/3 of my battery per journey to work.

I keep seeing these 3000w motors on gold rims on aliexpress, but they seem quite expensive, are these any good? And what are the benefits of a sine wave controller over a non sinewave?

Thanks again for your help and advice, even though I'm a car mechanic at heart, this ebike business is a lot more complicated than I first thought!

 

[dogman dan]

Go ahead, bump it to 72v as long as you don't try to do 20 miles at a time on it at that speed. Eventually, get the bigger motor. Or right away, after you enjoy the fun of melting it down.

But the thought of hauling ass like that being stealthy makes the morning coffee fly out my nose as I laugh my ass off. :lol:

Re the battery, only the RC lipo has anywhere near the c rate to handle 40 amps controllers, with only 10 ah of size. Come to the dark side, if you want cheap high power. Best of all, a smaller battery will prevent you being able to ride long enough to melt er down.

 

[chris-b]

Ok, ok maybe a 45mph mountain bike isn't that stealthy
We have stupid laws here in the UK regarding electric bikes, big brother is very quick here to kill your fun. Current laws say it has to be under 250w and pedal assist only, no throttle allowed. Segways, hover boards etc... are all banned.

I'll give melting my current motor a go first then, so rc lipo batteries are a must, also is there a particular controller you guys in the know, prefer? Maybe I could get 2 batteries and make them hot swappable.

 

[wesnewell]

have lvc set to 66-70V for 20s rc lipo
http://www.aliexpress.com/store/product/72V-1500W-50Amax-BLDC-motor-speed-controller-15FET-IRFB4110-Mosfet-52V-LVC-brushless-sensored-sensorless/313864_936095185.html

 

[999zip999]

At minimum you need a strong battery. A real battery. 60volt or 72volt then a controler 40mps. Yes they do make batteries for your triangle.

 

[chris-b]

Thanks again everyone, time to order a battery!!

 

[jokr]

Ιf I had your bike will not go over 35-38mph...45mph is too much.

Personally i like this controller
http://kellycontroller.com/kls7212s24v-72v120asinusoidal-brushless-motor-controller-p-1348.html

Small and will last in time.

 

[robocam]

What about that bike makes you want to limit it to 38 mph? I'm just curious.

Ιf I had your bike will not go over 35-38mph...45mph is too much...

 

[dogman dan]

The bike will tell you it's speed limit. If the frame tubes are very thick and torsionally stiff, it will handle 50 mph. If it's not, you'll get wobbly somewhere above 35mph.

Also, above 35 mph with a hard tail, a bump you don't see in time can make you do a front wheel stand. Very interesting, doing a stoppie at 40 mph with a bike tire. It's the tires that make really going fast so challenging. It's kid of like getting out of a car going 50 mph, and trying to keep up by running. You immediately realize tennis shoes are not built for 50 mph. Stuff you know how to do on a motorcycle is very different with a bike tire.

The naked bike may be fine for 50 mph, but the bike with motor and battery weight added might be different.

 

[chris-b]

I regularly hit 39mph on a certain hill and it still feels spot on. I use the widest stickiest slicks I can get. I've also upgraded the brakes as much as I can, and also regularly make sure the wheels are straight and true, and all nipples and spokes are tight. Bearings are cleaned and regreased also. I'd be happy going 50+ all day long tbh. I know what you mean about tyres, I tried 1.5' slicks and it just didn't feel stable enough. Now I'm on 2.2 and i can almost get my knee down :lol:
The stopping power this thing has got even with the heavy battery and rider is unbelievable. I strongly recommend upgrading brakes to the best you can get on any ebike. Saved my bacon a few times so far!

 

[chris-b]

Sorry, these new city jet tyres are 2.1in not 2.2

The frame also does look a little on the weedy side in the pic, but the tubes are wider than they are tall, plus it's a pretty big frame overall. The only thing I'd be worried about is where the motor bolts to the frame. That will have to be made stronger.

 

[jokr]

robocam:
Hardtail frame-fork-tyres.

chris-b:
As i see your fork is spring loaded with 28mm sanctions and definitely you need 32mm stanchion with air-oil fork.
Two torque arms...



Personally i have a gt karakoram 29er.
Fork changed from spring to air-oil with 32mm stanchion.I also want to upgrade my brakes to 4piston but the fork must have at least 34mm sanctions.
45mph/72kph is very fast to stop in time.
Hardtail and high speed isn't match 100%.

My next tuning is rear rim from 29" to 26" or 24" tubeless and match a tyre for comfortable riding over bamps.

I understand a fast bike is awesome but what about safety?

 

[chris-b]

Jokr:
I have some twin yoke/triple clamp (whatever you want to call them) forks I was thinking about putting on, but they are a bit too big. I'm going to get rid of those and get some thicker rockshox air/oil forks. The suntours that are on there now are holding up quite well for cheap crap, although I can notice very slight flexing under heavy braking.

I love my hardtail frame for the handling and manoeuvrability. As I said before its mainly road riding with very little soft off road. I'm not going to be going over bumps and holes at 50mph. Believe me I would love to have a stealth bomber type bike over mine, but the police will notice that straight away! Unless I get it registered to pay tax/mot/insurance etc... which kinds defeats the point of the totally free transport I have now with my stealthy hardtail.

As for safety, I always wear protective gear. I'm also a motorcyclist so I know what other road users are like. To be honest if riding was 100% safe I probably wouldn't do it.

 

[dogman dan]

I wasn't planning to hit that manhole cover bump at 50 mph either. But it was interesting.

But like I said, the bike will tell you when it's too fast for it's current load out. I think it will do ok as long as the battery weight remains under 15 pounds, located in the center. It's when you try to really load up with 25 pounds of battery that frame limitations start rearing up. Hard tail will actually be stiffer usually, so that helps.

 

[chris-b]

Indeed, an experienced rider can tell when there's something not quite right. Moving the battery to the center made such a massive difference, it was almost unrideable with it hanging off the back.

BTW if anyone's interested, I used an aluminium metre stick from my local hardware shop and bent it to fit around the frame then used a nut and bolt below the saddle and another bolt and wing nut by the battery to clamp it in. It's loosened in the pic so I can get to the charging plug. A bit of grinding to round off the ends and a bit of carbon wrap to finish it off! Battery doesn't budge no matter how much abuse it goes through. I also find a suspension seat post helps with the hardtail.

 

[jokr]

Here is my karakoram 48v/hs3540.
I use it almost every day.

Haven't decide yet if i keep it or tune it that is why it is naked.

 

[chris-b]

Did the bike come with 29ers? That back wheel looks like a really tight fit!

 

[jokr]

Yes 29er.
The Back wheel dimensions are 29x2.10 and has a bit more space left. In my opinion a hookworm 26x2.50 could be fit properly.