Looking for Recommendation for BBS02 Configuration

I have next to no experience with middrive kits, so if anyone could offer some suggestions for a BBS02 or BBSHD configuration? I'll be ordering from em3ev.

Bike:
2007 hard tail mountain bike, 8 speed cassette

Requirements:
Daily commute is 700ft elevation, 3 mile hill.
Needs to be able to survive 1400ft 6 mile climb occasionally
Ambient temperature can be as high as 90F in the summer here
I don't want anything faster than 40km/h, slower is fine.
I don't mind peddling, as i currently do this with no electric assist.
I'm not interested in a throttle, I would like this bike to simply just use PAS
I'm interested in Having a reliable system, over one that will potentially overhead, or cause excessive drive line wear.


Questions:
What chain ring size makes sense for this type of hill climbing, is the bling ring a better choice?
Can i get away with the BBS02 instead of the heavier BBSHD, and save some weight and cost?
Controller at 18amp or 25amp setup better for this? 36v or 48v?
Has anyone used the optional gear sensor, does it help with shifting etc?
Do these motors have temperature sensors, with auto shutoff or throttle back, so they will not self destruct?

Thanks.

I think how much weight you will be pushing, your rear gear ratio you want to run (wide/narrow gear ratio) and how fast you wish to climb hills is going to be a large factor in your decision and would need to be taken into consideration as well.

Once you figure out speed and power requirements you can go with the correct gear ratio. Here is a site that takes tire sizes, pedal speed, and gear ratios and determines max speeds for any gear.

http://www.bikecalc.com/gear_speed

We have the tdsz2, it is a less powerful and a little lighter than the bbs02 at 750w max but it has a torque sensor that adjusts power output to how hard you are pedaling and not by just moving the pedals.

Maybe my situation will help you figure out what you want. I originally designed my bike to do 30mph at 90rpms. I have a 42 chainring and 11-32 8 speed cassette and 27.5 plus tires. This gives me 10mph in 1st gear at 90rpm, which means I should not drop below 8mph for motor longevity. I ride with my dog and together we are 220 lbs. With a full battery we can climb maybe 8-10 percent grades without pedaling at 8mph. But I have found 8th gear is only needed down hills, I cannot ride over 25mph on flats without wiping myself out in short order.

I just ordered a 34 tooth sprocket, that will drop my top speed to around 25mph at 90rpm and 8mph in 1st gear so I can climb hills safely at 6.5mph. I also plan on swapping my rear cassette for a wide ratio 11-40 which will allow my top speed to remain but reduce 1st gear to 6.5 mph and allow me to ride up hills as slow as 5mph safely.

I think it is important to find your top speed that you need to commute and then give yourself as much power as you can for climbing hills. This way you can climb steeper hills and when you are climbing less steep hills you can be in a higher gear or you can use less power and conserve battery power.

I have only had my bike for a couple of months but this is what I have figured out so far. We have a lot of hills and help climbing them is what is most important to me.

Speaking from experience, Im currently running a BBSHD on a 29er MTB with a 52v, 14Ah battery, hot-rodded programming (1500w), 36t Luna One chainring in conditions similar to yours (It gets over 100 here), Im 185 lbs, bike weighs 63.
Last night I went for a ride in our local State Park, climbing some rocky, steep trails. Some of these trails are so steep that I couldnt ride up them without power behind the wheel. Maybe a pro could, but not me. I think the BBSHD could climb a wall if gravity wasnt an issue in my lowest usable gear (24t rear). Anyways, after my ride I still had 50% left on my battery and I had started out at 75%...12.4 miles with an elevation change of +/- 1642 ft (gps verified). I was beating it to death. At the top of the mountain, I checked temperature of the motor the old fashioned way, barely warm. I feel really sorry for my back tire though.

With the 36t/11t gearing on a 29er I can reach 30 mph pedaling like Lance in a time trial, but on average Im running around 23 on the street. Sounds about what you're looking for.

BBS02 vs. BBSHD. Reliability in question right there. I have no experience whatsoever with the 02 but Ive heard some not so great things about it if you are planning on beating your motor like I do. The HD has bigger windings so It can handle the heat better, the 02 has/had a bad grease issue that has to be taken care of pre-install. (not sure if its still like this).

36 vs. 48 vs. 52. I wouldnt even want a 48v battery but Im spoiled after riding 52. I think with a 36v you'd have to have a high amp controller just to get any kind of speed out of it at all. When i run down to 48v on my battery Im swearing at the bike but it still gets me there, with gusto.

Gear sensor is a must. I tried it without it and I'm surprised I didn't wreck the chain or teeth even though I consider myself careful. Its worth the cost. Cuts out the motor INSTANTLY upon shifting (sometimes if Im not, over rocky ass terrain) as it detects the subtlest of cable movement. Cuts out for about 2/3 of a second and youre back on the power. Works wonders.

Temp sensors, Nope they dont. But I have read a web article about using a $5 amazon digital aquarium thermometer poked inside the control wire area for that. Although if you keep the cadence high (80+) I doubt you're going to generate much heat.

It all comes down to your ride. Is it paved or dirt? 700 ft elevation in 3 miles, that's not exactly what I would call steep by any means (4%) I frequently do a 250 ft climb in less than half a mile in 36/24t no sweat (street) 9%. I could probably go 25 up that hill without stressing the motor too badly. Besides, these mid drives are internally geared (dont know the ratio) so if your pedaling 100 cadence, the motor is spinning several times faster, probably like 800+ rpm, way faster than a hub motor, therefore more heat efficient.

Im not rich but I saved the extra money for the HD just for the reliability factor. Luna was great, I recommend them.

bbs02

34t chainring

42t granny

Thanks for all the suggestions. the tdsz2 actually looks really interesting, but hard to get full info sifting through the 80 plus pages. Sounds like some people have trouble with stripping the blue gear, but maybe can be fixed with software update? Not sure if that is easily installed or available.

Any reputable sellers of tdsz2 to Canada?
Does the TDSZ2 support gear shift sensor, maybe it does not need it as much, as it uses a torque sensor?
Any way to have the TDSZ2 not start until a few revolutions of the peddles, to avoid stripping the gear on take off, or any option drastically slow down power rampup on start?
Any option for ebrake sensor, to also avoid stripping gear?

biketrix.com. based in canada.

wpenner said:

Thanks for all the suggestions. the tdsz2 actually looks really interesting, but hard to get full info sifting through the 80 plus pages. Sounds like some people have trouble with stripping the blue gear, but maybe can be fixed with software update? Not sure if that is easily installed or available.

Any reputable sellers of tdsz2 to Canada?
Does the TDSZ2 support gear shift sensor, maybe it does not need it as much, as it uses a torque sensor?
Any way to have the TDSZ2 not start until a few revolutions of the peddles, to avoid stripping the gear on take off, or any option drastically slow down power rampup on start?
Any option for ebrake sensor, to also avoid stripping gear?

Click to expand...

We bought ours from pswpower, it was $355 shipped. It arrived in about 10 days and we have been happy with it.

I read through that whole 80 page thread before buying ours. The blue gear is ok if you shift correctly. Keep the motor in the upper 75-100% of rpms and it should last a long time. The people that beat on those blue gears buy metal replacement gears, but they require more lube and they are supposedly noisier. I guess if you pedal and brake simultaneously it could be an issue but that is something I never do, however if you buy the motor with the throttle it does have e-brake levers for mechanical brakes included. There is currently no gear sensor however a member (casainho) is working on possibly implementing one in the future. The throttle is also nice to use as a clutch though, when riding in assist mode if you push the throttle 1/4 second before you shift it will stop the motor for a smooth shift. When pressing the throttle while riding in assist it pauses the motor for about a second or two before kicking back in.

There is a way to calibrate the unit on startup. If you turn it on and peddle around for 20 seconds or so at say 15rpm then the motor won't kick in until you get over 15rpm (whatever speed you peddle at when calibrating at startup is apparently set to zero speed. Also the motor goes by torque and not peddle speed. You can actually peddle and not have the motor kick in if you are not applying any force to the pedals. I do not think this is necessary though, I think the real issue for the blue gear is steep hills below 75% max rpms or peddle/throttle while braking hard, and the biggest issue is probably starting from a stop in a high gear.

Another nice feature about the throttle is that you can ride in eco mode where the motor will only apply about 1/3 the force that you apply from peddling, but when you reach a hill you hit the throttle for full power climbing. This should help to ensure long blue gear life.

We don't have a way to update firmware/software yet but casainho has been working on creating a program to edit the firmware settings. A new 52v version just came out that allows you to use 52v batteries, I would suggest getting that one if you decide on the tsdz2. If you have any questions just post them in the 80 page thread, there are lots of helpful people watching there