Thinking about DIY eMTB'ing my Diamondback Recoil 29er

[dunksalot]

Here's a pic of what I have to work with: https://www.amazon.com/Diamondback-Recoil-Suspension-Mountain-29-Inch/dp/B008O2FXCG

I would like to electrify my Diamondback Recoil 29er which I use for trail riding (nothing more than moderate difficulty). I've seen a lot of motors out there that are rear or mid-drive. Bafang would be super fun but that's a bit costly. I just want something that can hit 20 mph (I want a throttle) on flat land...basically something that can help me on hills so I can keep up with my teenage son.

Some helpful background: I want something that isn't fragile, is preferably less bulky and if the ECR is built into the motor that's even better, and I am comfortable doing drilling and soldering but if I need to go find a machine shop that's where I get lazy and this project gathers dust. Easy-to-build is worth more points than difficult in my decision cycle.

 

[Clyde]

Looks like a really nice starting point. You might look at the 750w Bafang BBS02 if the 1000w HD stretches the budget too far. The rear suspension and small triangle may present a challenge when mounting your battery, but it can certainly be done. Don't skimp on the battery!

 

[dunksalot]

Looks like a really nice starting point. You might look at the 750w Bafang BBS02 if the 1000w HD stretches the budget too far. The rear suspension and small triangle may present a challenge when mounting your battery, but it can certainly be done. Don't skimp on the battery!

Thank you Clyde. I can make budgets work but at some point it gets high and then I start to stare at the Luna X1 Enduro and drool. How cheap do you think I can get a kit w/battery? Also, I am indeed concerned about limited triangle headroom...not much available.

 

[indianajo]

You can't go front hub because this bike has a suspension fork.
If you go rear hub, the most you can have is a 7 speed sprocket cluster. This bike has an 8 speed sprocket cluster which with motor would be too wide for the fork dimension.
You can put a dd rear hub in for ~$200 + battery. Battery price goes by capacity. I get 30 miles out of 17.5 ah 48 v I paid $620 for, but I may have more short hills than you do. Sn Diego has access to the sierra. Don't try to ride from the sea to the sierra with a geared hub, even though the performance is better. More than 1000' rise in 15 minutes they will overheat. Direct drive hubs are cheaper, cool better on steep grades, but chew up the watthours uphill at slow speed. Geared hubs are more fun, accelerate faster, and don't drag unpowered except the GMAC.
The hard part of installing a hub drive is rigging a torque arm. I made mine, but you can buy them. SS hose clamps do not provide sufficient torque reaction IMHO. I made my clamp out of solid sheet metal and #10 machine screws.
I find hub drives are more maintenance free if you double nut the axles. For most cheap hubs the 2nd nut can't be bought. You may have better motorcycle shops in SnDiego than we have here. The online bike supplies I deal with think nuts come with only 1 dimension, which they are not clear whether it is the inside measurement or the outside. I bought some (refunded) where no dimension was 14 mm. I made my 14 mm x 1.75 nuts with a tap I bought.
ECR built into the motor subjects drive components to the heat of the winding. Go-Swiss drive went broke doing that, I don't suggest anybody search for that bad plan. My controller is mounted on the seat post on a clamp, the seat keeps the rain off.
Mid drive requires more machine work. I'm no expert on that. If you go that way, bafang requires you to run the motor all the time or drag the motor with your feet. 7/8 speed chain would last better than 9 speed or 11 speed chain but may not be compatible with some mid drives
You'll need a good terminal crimp tool to wire up the battery. some batteries come with solder connections, the XT90 joints I make are not reliable at 30 amps. The shop one on the battery is fine, but you have the make the one for the bike side. Dorman/t&b/ideal/panduit/3m/TE connectivity crimp terminals are reliable at 30 amps. The ****ese substitutes melt out. I used insulated .250 flags or .157" bullet connectors on the ebikeling motor. Swap male & female so you can't plug cables in backwards. I used a 30 amp AGC fuse in a littlefuse holder.
Think about battery security if you are ever going to lock up & park your bike. Mine is captured in angle aluminum with inaccessible screw heads. Thieves have had 2 tries at it while I was shopping, failed. A snap on battery bag is quick, easy, and pops under the theives arm in seconds.
US battery sources I trust are lunabike & ebikeling. Shicks says california ebike has good batteries, I haven't tried them. I got 2 piles of trash from Amazon bttrbattery & ebay sun-ebike . Don't bother.
Happy shopping & installing.

 

[harryS]

Nice thing about the BBS02 and BBSHD is the simplicity of the wiring. The controller is in the motor housing, All you do is run a 4n1 cable (it has display, two brake wires, and a throttle) to the handlebars. Sure, 25 mph is there with 48V and the BBS02, The top speed varies with the size of the chain wheel.

Some of the hub motor kits are available with a 4n1 cable from the controller, but you still have to put the controller somewhere, and not much room on an FS bike, Only the heavier hubmotors, like 15 pounds, have the controller in the hub, That probably ruins the handling of any bike unless it's in a straight line on the street at 30 mph.

Geared motor kits are running around $300 these days. The BBS02 is about $100-200 more?

 

[JRA]

There is also the TSDZ2 which is comparable power wise to the BBS02 has an internal controller but with a torque sensor as opposed to cadence sensor. I have two bikes converted with them that see use in harsh environments, think snow to sand, My newer motor has firmware that gives you very similar info to that of the manufacturers in a less clunky case than the stock that allows you to fine tune the assist levels for your needs as well as it has a throttle. re-cycles is who I use as one of the principals has led the way in tweaking them since their introduction here in 2016.

You might fit a small 10/12 Ah HL case in the triangle which would be your best bet overall. Quality is hard to discern as an expensive battery might be no more than a mid priced one. I have a 12ah HL case battery I paid $450 dollars for shipped that has the newer 21700 cells and was assembled in the USA by a reputable company. $400 for one with 18650 cells is I feel a good pricepoint to look for and most importantly how fast will you get it as it usually takes awhile, unless from Grin, to get things out.

 

[Clyde]

Another vote for the TSDZ2. Had a look at them while considering a more lightweight build, and they look like quality units which are easy to mount if your downtube curves out and then up from the bottom bracket. Torque sensing is a feature I wish the BBSxx drives had.