E=FreeRide

[OCD]

Hi all!

Been busy with other things lately but Don from Sunahme Bikes in Ladysmith invited me out for a group ride and loaned one of his super high powered electric mtb. I was hooked. That meant another bike build was needed, a mountain bike is one thing I've never tried to build before. I used the frame from an older Norco Atomic I had, put it into the jig to transfer it's measurements, relationships and angles. After all, Norco likely spent a lot of R&D money to come up with those numbers.

To start, I'll be using a QS Motor 205 series 30H hub motor which are conservatively rated at 1500 watt continuous, but easily take 5K watts for extended periods. It'll be running 72v 22.5ah x 80amp controller for about 6000 watt output. It also has a functional 7 speed cassette for 'human assist'. Should be about 90lbs of fun when finished. The frame and shock weigh 25lbs



Like many of you I usually like to begin a project with a bit of CAD. You will note I was originally going to put the controller under the front downtubes but realized after I could fit it inside the triangle if the battery and shock were dropped down.


Here's the beginnings of the base of the project

 

[LukeTheJoker]

I'm always a fan of the scratch builds!

Luke.

 

[Fruttolo]

Nice build, but if I can give you some advice, the rear suspension is not gonna work good. You have too weak progression in that geometry, you should raise the swingarm shock mounting point an inch or two to get better geo's and avoid always bottoming out.

What's the intended use of this? Real freeride or just light duty stuff?

 

[OCD]

We will see what the bike can take as it was built as an experiment anyway. In retrospect I agree that the shock ratio is now off as you can see it was originally planned to be about 2" higher with the battery along the top tubes. I made an unresearched change and decided to drop the battery/shock down to fit the controller inside the triangle.

I'm hoping with the 600# spring I have on order, it won't bottom out too regularly. Currently with the original 450# spring it doesn't bottom when I bounce on it but that's not the same as riding over rough terrain. With a hub motor in the back wheel there won't be any big air taken as the wheel wouldn't survive long term. I haven't finished the bike and already I've learned a lot.

 

[OCD]

Finished the bike and had a couple of test rides today. After a 20 minute blast around the neighbourhood, a friend called and suggested I come out with them and put the bike through some off-road action. Even with the 48 volt 30 amp BMS pack I had on hand it really did well considering it will be getting a 72 volt one soon.

 

[LukeTheJoker]

Looks awesome, love the white.

Luke.

 

[Fruttolo]

May I ask how much would the electric components cost?
I'm looking into a non exactly bike project I would electrify with a front wheel hub motor and I'd like to get 60-65km/h max speed for 20-25km, is there a "ready" kit you would get for a similar application?
(No pedal power, just electric motor and "throttle")

Thanks and sorry for spamming your thread further

 

[OCD]

No problem Fruttolo, forums are the perfect place to ask question of those that have already done something you're thinking about and the best way to eliminate costly mistakes.

I will quote prices in Canadian dollars but basicly in USD subtract 25%. If you run 48 volt you will only get 54km/h so you will need 60 volt to get 70km/h and 72 volt will give you about 80km/h in a 26" with a med/fast motor winding. The price of the battery is largely based on the number of cells so, whether you have 48v 30ah or 72v 20ah it should cost about the same as they both have 130 cells and will have similar range because the total watt hours are the same. The pictures show a couple of temporary batteries but I put the proper battery in today.

I bought a high discharge 48v 30ah battery from EX-battery.com which cost $1600 by the time it arrived in my hand. I sell QS Motor hub motors which I hand build with a double walled rim and butted spokes for $500cdn. I'm using an 80 amp controller which will work with 48 - 72 volts for $225cdn, throttle is about $20cdn and a few bits of wire, some connectors and that's about it. I also use a Cycle Analyst monitor for speedo and e-fuel gauge which is about $140cdn, it's an amazing instrument that will tell you more that you thought you needed to know. I hope that clarifies things. Please feel free to ask any question about things your're fuzzy on.