Gear shifting technique

[Statesman]

I currently am using a Reid Cycles Urban X2, with a BBS02 750w M/D motor. It has a 9 speed Shimano gears. I have just had surgery on a knee injury, making my usual pedal assist ride, a throttle only, for the first week or so, setting the PAS to 0 and using just the variable throttle.

I assume that using throttle only, you travel thru the gears 1-9 just like as if you were peddling?, Would you burn out the motor if you just left it in say 3rd or 4th? My other question is the technique that should be used to change up and down in throttle/no pedal mode. Do you let off the throttle, change then reapply the throttle or do you just keep the throttle steady and shift?

I would assume that either way is going to place strain on the drive train/chain etc, but just wondering which method, or any other, is least damaging to the drive train

Many thanks, Chris

 

[dogman dan]

Back off the throttle would be easier on the chain. But it depends on how much power you have on at the moment whether you really need to back off to shift. I don't think you need to back off to no throttle.

Just bear in mind, full power is like a sprinter at full effort. I'd say the low gear shifts when you are going 5 mph are harsher than the shift from 15 to 20 mph.

Use your judgement, if the shift sounds really harsh, surely it is.

 

[Statesman]

Thanks for your quick reply! TBH, I have never had the throttle any where near its maximum. I seem to be most happy at the quarter to half position. I do notice when I I go from a standing start in 1st, the bike does accelerate quite rapidly.(Throttle mode only) and I'm unsure when I should be shifting up (A rev counter would be handy, LoL)

So if I was to just leave it in first say, from a standing start, two things will likely happen. The motor will over rev and explode (if its not protected*) or the bike will only get to a certain road speed? To increase the road speed at a given throttle value, 2nd gear must be engaged, just like a regular bike?

*I am not sure if the BBS02 has "Over Rev" protection

 

[Ykick]

BBS02 will not overspeed.

For it to be in the “happiest place” it should always run out to it’s max RPM. Use a lower bike gear than you “think” you need. In fact, install the smallest chainring you can find.

With my 52V BBS02 that works out so that my legs provide little to no actual pedal input. But, my battery power consumption is at it’s lowest. Installing a a power meter (even if temporary) is a good way to better understand how the motor power backs off considerably at higher motor RPM.

My technique for shifting is to select a lower level 1-5 PAS but ride using the throttle. When shifting I let up on the throttle, make the shift and reapply throttle. The lower PAS level backs off motor power when lifting throttle and greatly reduces stress to the shifting mechanism.

If cruising along, I often bump up to level 9 and let the PAS keep max motor RPM applied to whatever bike gear's needed for the road speed.

Lately, I pretty much just use level 1 and level 9. I don’t bother with the levels in between anymore.

 

[Statesman]

Thanks yKick,

I think this is where Im getting confused. I have been told to set PAS at 0 (I have 0,1,2 and 3) if no pedal input. As I wont be peddling at all, (for the time being) that seemed to make sense. If I used PAS 1 and 3 (not peddling), what are the benefits to the motor efficiency/longevity, as against leaving it on PAS 0, (not peddling)?

The throttle will work on this bike @ PAS 0, 1, 2 and 3)

Sorry for all the questions

 

[Ykick]

No worries about questions, 'sorry I'm not a better writer.

I never use level 0 although my Luna BBS02 is programmed to allow throttle with level 0. Not sure why someone bothers with 0? 1-2 reduces power enough to make a gentle shift when letting off throttle.

But as I said, allow the motor to wind up to max RPM at any and every opportunity. That will deliver the best electrical efficiency while reducing heat in the motor/controller and strain on the gear internals.

I like 1-2 PAS for riding slow mixed in with pedestrians or in many cases here in NYC, between lanes and stopped cars. I don’t want a lot of power or speed under those conditions which is why I don’t use any throttle at those times.

But moving with stop & go traffic I tend to use only throttle. I leave the PAS in 1 or 2 just for when I might need to slow to a crawl speed and of course, reduce strain when shifting.

When I want more of a “cruise control” I usually bump up to 9 and let the PAS keep me powering along in a low enough gear so that the motor is barely pulling much current/Amps.

I was much more experienced with hub motors and in the beginning I didn’t like the BBS02. But since I’ve reduced the size of front chainring and learned the techniques described above, I’m quite fond of it now.

 

[docw009]

Statesman, if your display supports it, try going to more PAS levels. When I only had 3, PAS 1 allowed me to pedal up to 18-20 mph, which made it too hard to keep a slower pace with non-powered bike friends.

I always roll off the throttle when shifting, same as I did on motorcycle or with a stick shift car. Power shifts are rough on the drive train. Unless you have a BBS02 gear sensor that does this automatically, I think it's a good habit.

I don't believe the PAS level has any effect on the motor speed available thru throttle. On my BBS02, throttle works in PAS 0, which is different from some other ebikes I have ridden where it does not. Not sure if all BBS controllers allow throttle in PAS 0.

I've also read the advice about keeping the BBS drives spinning fast, but I use mine more for assist. I just try not to lug it in high gear.

 

[drew12345]

+1 on the gearsensor

 

[Ykick]

Statesman, if your display supports it, try going to more PAS levels. When I only had 3, PAS 1 allowed me to pedal up to 18-20 mph, which made it too hard to keep a slower pace with non-powered bike friends.

I always roll off the throttle when shifting, same as I did on motorcycle or with a stick shift car. Power shifts are rough on the drive train. Unless you have a BBS02 gear sensor that does this automatically, I think it's a good habit.

I don't believe the PAS level has any effect on the motor speed available thru throttle. On my BBS02, throttle works in PAS 0, which is different from some other ebikes I have ridden where it does not. Not sure if all BBS controllers allow throttle in PAS 0.

I've also read the advice about keeping the BBS drives spinning fast, but I use mine more for assist. I just try not to lug it in high gear.

True. At least on my Luna programmed BBS02 throttle provides full motor speed no matter what PAS level is selected.

 

[MikeSSS]

Interesting thread!

Is there any throttle delay, when increasing or decreasing throttle, with the BBS02 or BBSHD?

Also, to shift, just back off the throttle, same as on a motorcycle, and shift. Back off completely and pedal or back off to very low power, is either OK?

Reason for asking is that I'm considering the BBS02 or BBSHD for my full suspension bike.

Thanks

 

[WoodlandHills]

One thing to keep in mind so that we are comparing oranges with oranges: a Bafang with 3 PAS levels has levels 1,5 and 9 available compared to one with 9 PAS levels. When ykick is in PAS level 9 he is in the same level as your PAS level 3, until you either reprogram your display or get another with 9 levels of PAS, ykick's level 2,3,4,6,7 and 8 are not available to you.

If you backpedal the tiniest bit just as you shift and then immediately resume pedaling the delay in restoring power when in PAS will allow you to roll the chain up onto the next cog under muscle power before the electric power hits again. This lowers shock loading considerably as well as saving the cogs. You can also achieve the same result with judicious use of the throttle. And for long motor life: gear it like a two stroke that needs to be run at redline to make power. A Bafang makes torque at any rpm but it's happiest when it's wound out: unlike an ICE an electric motor gets hottest at low rpm so keep it spinning to keep it cool.

 

[Statesman]

Thanks for all your replies. As per my OP, this question refers to Not peddling at all. I understand that PAS, regardless if is calibrated from 1-3 or 1-9, offers motor assistance whilst peddling only (with my bike, up to 25km/h). Using the throttle provides motor power regardless of whether peddling or not

I now understand that its wise to slightly reduce the throttle input whilst shifting, but my question still remains. If the BBS02 likes higher RPM/Less Load, why not just leave the bike in 1st gear?

As for the chosen PAS level (1-3 or 1-9), I see this being as not applicable, as you are not peddling?, therefore the bikes motor will perform as well at PAS 0, as it would at PAS 3 (or 9)?

 

[dustNbone]

I don't use PAS on my BBS02 at all, it's been disconnected since the first time it pissed me off. If you can, make sure the throttle is set to Current mode in the programming software as opposed to Speed mode. This will allow much better modulation of power via the throttle.

There are two ways that I shift, for a slow shift I throttle off completely as roll the pedals one slow revolution and shift simultaneously. Then get back on the throttle before you're finished turning the pedals, this avoids the lash of the freewheel disengaging and engaging. This method might work with the throttle in Speed mode, but not as well.

The other way, for a quicker shift, is to slack off the throttle just to the point that it unloads the driveline, but doesn't stop turning, shift, and get back on the throttle. The key is to not let things come to a halt, avoiding the driveline lash I mentioned above. It takes a bit of practice but once you nail it you'll do it by nature. This method will not work with the throttle in Speed mode.

The BBS02 is way more efficient running at high speed, I tend to keep it running in the zone where the current is tapering off close to the motors upper speed limit. If it starts to fall below this zone, the current (and torque) increases quite fast and that will pull me up a moderate hill without needing a down shift. Also in this zone the RPM is low enough to alow me to assist it with the pedals, at a high (for a human) cadence. If this cadence drops to a comfortable (for a human) one, it's time to downshift.

 

[dogman dan]

You would leave your bike in 1st gear, if the max speed of 1st gear is your desired max speed.

I agree with Ykick, upshift only for the purpose of going faster. Don't cruise slow in a high gear. Electric motors are at max efficiency when they are at max rpm. It's just totally different from any gas motor. wind that sucker out.

The shifting advice I see just above sounds good,, I never said get 100% off the throttle. Just back off enough to make the shift sound normal to you. if you are not pulling a lot, you may not need to back off at all.

Do avoid the temptation to just put it in a high gear, and then leave it there,, if you do that, it is harder on the motor.

 

[Statesman]

Thanks for all your replies. I'll practice the shifting technique and leave it at PAS 0 and see how I get on. Once I start peddling again, in a few weeks, then I can go back to using PAS. Many thanks, Chris

 

[MadRhino]

The whole idea of shifting gears is to keep the motor running within its optimal RPM efficiency scale at any speed that you ride. It is simple but not that easy when the riding conditions are extremes. Sometimes, keeping the motor happy is making it hard on the drivetrain. Sometimes, the riding conditions are not letting you shift gears when you would want to.

That is why I prefer a hub in the mountain trails. The theory would make a mid drive a better choice, but the reality of the terrain is making a hub much faster, and reliable.

 

[d8veh]

Firstly, anybody that hasn't got the gear sensor should get one. They make a massive difference.

Using the throttle only, you have to keep the motor at its optimum speed for best efficiency, which is about 75% of its maximum RPM. If you run the motor in too high a gear with full throttle so that it's running at less than 50% of its maximum RPM, it'll run inefficiently, heat up and burn out. That's why you need gears. If you left in in one of the middle gears all the time, it would be just like a hub-motor, but why would you want to do that when a hub-motor is cheaper, more efficient and a lot easier on your drive train?