What do you guys think of this ebike setup for off road use?

[Tom]

Hi guys, I am looking to build an ebike for mountain logging road use. I don't care about speed, just something that will get me up 4 miles of 10-15% grade hills with some pedal assist. Here's my current thinking:

Hub: BMC geared hub (rear wheel) from ebay or evtech w/ 25a controller ~$600
Battery: ebay duct tape 36v 20ah LiFePO4 ~$400
Bike: 2002 Giant Rainier (already own)

What do you guys think about the bike I plan to use? It's what I use currently use for biking logging roads, it's light, has decent components (including disc brakes) but wasn't cheap by my standards and I'm wondering if it would be smarter to get a cheaper dual suspension bike with a stronger frame and not risk ruining my current non e-bike?

I have the option to spoke the rear wheel with 12ga or 10ga. Is 12ga strong enough? Or should I go with 10ga?

I plan to go with the ebay duct tape batteries because I need lithium, they fit my budget, and my usage won't be that frequent so I think it makes sense for me even if they aren't the quality of LiFePO4 costing twice as much.

 

[deecanio]

Hi Tom,
your setup seems good for your use.
the bike looks ok for modding, all your measurements will be ok on that type of bike and it has a big triangle to hold your packs should you choose to use it.
I thought i would also say from experience that if you ride and enjoy the bike as is then keep it as is. you can get a second hand complete bike for reasonable money and it also gives you the chance to "pick for purpose" rather than adapt" - in my experience there's not much in it financially between buying a second hand bike and getting nickle and dimed to convert another.
i say this as i had a similar bike and chose to convert that, the problem is if the bikes not running then you dont ride at all!!
As of last week im looking for a new frame to mount the kit so that i can put the mtb back to just that my 28lb mtb, then if my ebike is off the road i can still go for a ride using my legs alone.
That said it will still collect dust once my new bike is built up hehehhehe


cheers


D

 

[Drunkskunk]

Sounds reasonable, but I would go with a 40 amp controller, and 48 volts or more for better climbing abilities

 

[Freddyflatfoot]

Have you thought about a BB drive, with say a Unite MY1016, running at 36v?
Lightweight motor, able to keep current gearing with right freewheel crank, and at 36 v, 20A controller, plenty of grunt.
The benefit of the chain drive, can get your power down to really low speeds for hill climbing, especially over rough ground and obstacles.
maybe even Safe will chime in here with his thoughts.
BTW, I'm running a similar setp on a Jamis hardtail, and still have my 9 speed cluster, but only have two chain rings at front, one for road use, and one for off road use (28t).
System works really well, but at only 24v, does run out of puff a bit too easy, Would definitely be better at 36v

 

[yoyoman]

I bought a 36V scooter for parts for $25. It really just needs a new chain, but I'm thinking I'd rather repurpose it for an electric bike.

Are there any plans, parts lists, or good photos for how I could use this motor (MY1016 36V 500W) on my mtb? Conquering hills is more important than going the distance, so I think this is the better route for me.

 

[dogman dan]

Re, the original post, A cheap full suspension mtb has the advantage of steel rear swingarm. I personally feel its pretty important, and nowdays they are coming with disk. The forks arent much good, but could be upgraded. keeping your favorite bike as is , is wise in the long run. I just bought such a bike at a garage sale for $40 and it still has the nubs on the tires. Weight won't be so important once powered.