My first DIY e-bike

[John84]

I am considering building my first e-bike (MTB) and was looking for advice on what kit to get and from where. The bike is strictly for off-road usage on privately owned land so speed limit is not an issue.

From what I have read, I could get a 3000w motor (maybe the MXUS hub motor) with a 80v controller and a large battery pack (at least 1KW).

Any suggestions?

 

[tommie]

Wouldn`t be my choice, it will turn out a big heavy bad handling contraption and go through your battery in no time.
One of the mid-drive 1kw options coupled with a 52v 17aH battery will give you all you need.

(off road, private land and all that drivel, of course )

 

[RobF]

I am considering building my first e-bike (MTB) and was looking for advice on what kit to get and from where. The bike is strictly for off-road usage on privately owned land so speed limit is not an issue.

From what I have read, I could get a 3000w motor (maybe the MXUS hub motor) with a 80v controller and a large battery pack (at least 1KW).

Any suggestions?

Buy a petrol motorbike.

 

[danielrlee]

What's your budget?

 

[John84]

@danielrlee I could go as high as a little over 1K (GBP)

EDIT: 1K for the battery, motor and controller.

 

[John84]

@RobF If I wanted a petrol motorbike, I wouldn't have posted here.

 

[Trevormonty]

@RobF If I wanted a petrol motorbike, I wouldn't have posted here.

Given your specification, a electric motorbike is what you are after. Petrol ones are better value.
Once you start going over 500-750w then you are getting into motorbike territory.

 

[Deleted member 4366]

I am considering building my first e-bike (MTB) and was looking for advice on what kit to get and from where. The bike is strictly for off-road usage on privately owned land so speed limit is not an issue.

From what I have read, I could get a 3000w motor (maybe the MXUS hub motor) with a 80v controller and a large battery pack (at least 1KW).

Any suggestions?

That's a lot more powerful than the sort of things we deal with here. I can tell you that £1000 might just about get you a battery, so you need to increase your budget a lot. Basically, you need a good spec downhill bike, which will cost you a lot more than £1000 before you start. It needs to have good hydraulic brakes and fairly wide tyres. You need to think about how and where to install the massive battery and controller. You'll also need a Cycle Analyst or similar to control the power.

You'd be better off asking your question on Endless-sphere, where they regularly build such bikes. You will be able to see some examples of what you'll be aiming at.

 

[John84]

@d8veh OK, I will go bother them.

£1000 for a battery? Sounds steep. What capacity is it?
I have seen these bikes where the battery and controller are attached to the frame, between the rider's thighs.

 

[wheeliepete]

D8veh is right in his suggestion to look on ES. It's the place where the big boys play and it will give you a much better idea of what is involved in building a good and more importantly safe high powered ebike. When you start playing with 80v+ batteries and high amp controllers you need to have a degree of understanding, which with respect, I don't think you have. Keep reading and learning, post your ideas on ES and with luck you will end up with a bike that will scare the sh#t out of you.

 

[Deleted member 4366]

I have seen these bikes where the battery and controller are attached to the frame, between the rider's thighs.

They won't give you 3kw. They can only give about 1kw max.

Typically, they're 500wh. If one could give the necessary power, it would last for about 7 minutes at 3kw.

 

[danielrlee]

@danielrlee I could go as high as a little over 1K (GBP)

EDIT: 1K for the battery, motor and controller.

I think you'll need to double your budget for the type of build you're thinking of and that's before sourcing a suitable frame.

What are your expectations when it comes to top speed, range, bike weight and type of riding?

 

[John84]

@danielrlee

In regards to top speed and range, the more the better.

I read somewhere that a 3000w MXUS coupled with a 72v sinewave controller and a large battery pack (say 72v 20ah) can reach even 50mph and have decent range (at lower speeds).

I looked into crank drive motors (BaFang middrive?) by their are not DIY-friendly for newbies so it is better to get a rear hub motor (like the MXUS)

 

[danielrlee]

@danielrlee

In regards to top speed and range, the more the better.

I read somewhere that a 3000w MXUS coupled with a 72v sinewave controller and a large battery pack (say 72v 20ah) can reach even 50mph and have decent range (at lower speeds).

I looked into crank drive motors (BaFang middrive?) by their are not DIY-friendly for newbies so it is better to get a rear hub motor (like the MXUS)

Your budget is totally unrealistic. You're looking at around £3000 all in for a reliable build based on the spec you describe. The battery alone will cost you £1k.

The difficulty you have is that such a spec requires a battery almost impossible to mount on a regular FS bike frame. As stated previously, you're essentially wanting a lightweight electric motorbike. Although way over your current budget, have you considered something like this:

https://em3ev.com/shop/?prod_cat_=ebike-packages

EDIT: If I were to offer you sensible advice, I would advise to aim lower for a first build. You should be able to build a decent bike using a BBSHD for £1500.

 

[John84]

@danielrlee

I found these online.

3000w MXUS Rear hub motor : 380 EUR
72v/25AH Battery pack : 650 GBP

Am I missing something? How did you get to £3000? Plus the battery above is triangular and can probably fit in the frame of a standard MTB (which I buy new from Halfords for around £500)

 

[danielrlee]

@danielrlee

I found these online.

3000w MXUS Rear hub motor : 380 EUR
72v/25AH Battery pack : 650 GBP

Am I missing something? How did you get to £3000? Plus the battery above is triangular and can probably fit in the frame of a standard MTB (which I buy new from Halfords for around £500)

Firstly, don't buy a new bike as it'll be a waste of money. As soon as you start to modify it, the warranty will be worthless. You'll need a decent full suspension bike which you should look for used. Even then, you'll struggle to find one with sufficient space to mount such a large battery.

Although it would probably just about do the job, IMO that battery isn't powerful enough for what the motor will really want. Minimum 80A continuous for £1K is a more realistic figure:

https://em3ev.com/shop/em3ev-72v-20s10p-rectangle-battery-pack-24-5ah-29-5ah/?currency=USD

Controller £2-300
Cycle Analyst £160
Suitable bike £500-1000
Miscellaneous costs £200

You should also seriously consider using moped rims & tyres at these power levels, since bicycle wheels & tyres are not built for the task. Add another £300.

Add another £150 for a full face helmet and the same again for additional protective gear.

It all mounts up.

 

[DynatechFan]

This thread/idea is way out of my ebike experience but a 9kg wheel and direct drive - that doesn't sound fun - and I can imagine the potentially really high torque could wreck a rear frame hanger, especially once you cut away metal to fit the 16mm axle in that hub

 

[wheeliepete]

Ok, so to get 3000w from your MXUS motor you will need to run it with a min. 50 amp controller. Your battery is spec'd to supply 50amp continuous, great, BUT the cells in the battery are only spec'd to supply 8 amp max. current. This means that you will be maxing that battery out most of the time, it will get hot and fail or catch fire. You need a battery pack made of cells that can deliver 20 amps con. Give Jimmy at BGA a call and he can spec. you a battery that will do the job. Prob. around 1k.

 

[danielrlee]

a 9kg wheel and direct drive - that doesn't sound fun

It does when supplied with 6kW+

 

[DynatechFan]

It does when supplied with 6kW+

I'll get my coat . . .