Question about Tongsheng PAS levels and smooth pedaling- SOLVED!

[freckles]

SOLVED!!!! The clunky pedaling was due to the 52T front chain ring. I put the original 42T back on, shortened the chain (stock bike was 52T) to fit and it works beautifully with no clunky pedaling no matter the cadence! Thank you all for your suggestions!!!!

I added a Tongsheng mid drive to a Tern Short Haul bike- its a 20" wheel, changed to a 52 front chain ring and 155 mm straight cranks. Not using speed sensor or brake cut offs.

This is my first ebike, first mid drive.

Noticed "clunky" pedaling from the start. The best I can describe it is- some resistance then feels like it slips when pedaling=clunky, on PAS 1 and 2.
At a higher pedaling cadence, it improves somewhat but still feels a bit "clunky".

I thought this is how it just is but very recently tried PAS 3 and 4- what an amazing difference! No more clunky pedaling no matter the cadence. Just smooth pedaling and incredible bionic legs!

I understand PAS 1 is minimal assist and imagined I would mostly be at PAS 2 with occasional 3 and 4 for boosts but the pedaling is so smooth at the higher PAS levels I don't want to go back.

For those with stock Tongsheng experience- do you experience some pedal clunkiness on PAS 1 or 2 too and just ride at higher PAS levels?

 

[Catalyzt]

TSDZ2B on one of my two bikes, pro install, filled with grease, no sensors or cutoffs. Experimental build, 29'er, 42 pounds, very wide bottom bracket, very wide gear range, chain line issues so 1st gear (52t) is not usable, the crank is 42t. I may wrench on it some this weekend, the builder (Pedaluma) and I have a crazy idea for moving first gear further outside.

No clunky pedaling 'from the start,' and certainly none at PAS 1 or 2. It's generally smooth and very efficient-- I had over 37 miles of range with well over 2,000 feet of vertical on the last charge-- but it does have some odd quirks.

To speak to your specific situation: I did notice, on one ride only, clunking at the same cadence as crank rotation. However, this was at max assistance and max pedal pressure. It sounded like a sound that was coming from 'inside' something. Repeated the same ride the following day, rode the same way, and no problems.

PAS 1 is pretty weak. There is no resistance from the motor while coasting or ghost pedaling, but as soon as the toque sensor engages the motor, it feels like there is some kind of resistance somewhere, so PAS 1 is not much different than 0 PAS. It's like it's +30%, but I've got 20% friction canceling it out, so it's maybe +10%. Note that I probably only recognized this because my other bike has a Shimano E5000 that seems to have no friction in any situation. On the Tongshen, PAS 2 is more usable, probably +50%, PAS 3 close to 100%, PAS 4 is much more powerful-- and there seems to be a 'super power' mode that only engages in low gear when I'm applying a lot of human torque.

So it's funny-- feels like a 50nm motor in most situations in 1 and 2, maybe 60nm in 3, 80nm in PAS 3, and 90+nm in Mystery Climbing Mode.

Pedal will probably chime in... knows a lot more than me. Right now, I'm wondering about your cranks. And to me, 52t is a ginormous chain ring, but there are huge hills where I live, so of course I would think that!

 

[EMGX]

I added a Tongsheng mid drive to a Tern Short Haul bike- its a 20" wheel, changed to a 52 front chain ring and 155 mm straight cranks. Not using speed sensor or brake cut offs.

This is my first ebike, first mid drive.

Noticed "clunky" pedaling from the start. The best I can describe it is- some resistance then feels like it slips when pedaling=clunky, on PAS 1 and 2.

For those with stock Tongsheng experience- do you experience some pedal clunkiness on PAS 1 or 2 too and just ride at higher PAS levels?

Not at all. Both of mine deliver completely smooth and natural feeling assist in all levels with or without speed sensor (no advantage running mine without speed sensor and some disadvantages to not using it).

 

[harryS]

You're waiting 10-15 seconds with no weight on the pedals after power up? That is for the controller to calibrate the torque sensor. Hopefully, this is what causes your lack of even torque response.
.
I am guessing it's a torque sensor issue. On my first one, the sensor must have had a low output signal, because it barely worked in Eco and Tour, the first two levels. At the highest level, it was somewhat uneven. I modified it with third party firmware to get more boost at lower pedal pressures.

.There's a hidden menu setting to show you what the controller is seeing from the torque sensor, but I never got it to work.

 

[freckles]

You're waiting 10-15 seconds with no weight on the pedals after power up? That is for the controller to calibrate the torque sensor. Hopefully, this is what causes your lack of even torque response.
.
I am guessing it's a torque sensor issue. On my first one, the sensor must have had a low output signal, because it barely worked in Eco and Tour, the first two levels. At the highest level, it was somewhat uneven. I modified it with third party firmware to get more boost at lower pedal pressures.

.There's a hidden menu setting to show you what the controller is seeing from the torque sensor, but I never got it to work.

Yes, I bring my bike out, flip the kick stand and turn it on. While its booting up I'm locking my door, putting away the stair ramps...not timing it but I'd guess its at least 10 seconds?

 

[freckles]

Not at all. Both of mine deliver completely smooth and natural feeling assist in all levels with or without speed sensor (no advantage running mine without speed sensor and some disadvantages to not using it).

Are you riding stock or with osf? How's the assist feel on PAS 1 and 2? I can hear motor turn on when pedaling immediately but with that odd clunky pedaling on PAS 1 and 2.

 

[EMGX]

I bought mine (a 48v 750w and a 36v 500w) from eco-cycles. I think they might tweak the settings but I'm not sure about that. I'm not interested in trying to program them myself, they have worked fine right out of the box. Not clunky, level 1 is low assist but definitely helpful on hills, I mostly ride in level 1 or 2 (or no assist when able) which provide all the assist I usually need, occasionally use level 3 on steep terrain, rarely use level 4 (or level 5, my 48v has a C3 display with 5 levels of assist). Your description sounds like something is off. Why don't you try with the speed sensor hooked up to see if that makes any difference?

 

[Catalyzt]

I bought mine (a 48v 750w and a 36v 500w) from eco-cycles. I think they might tweak the settings but I'm not sure about that. I'm not interested in trying to program them myself, they have worked fine right out of the box. Not clunky, level 1 is low assist but definitely helpful on hills, I mostly ride in level 1 or 2 (or no assist when able) which provide all the assist I usually need, occasionally use level 3 on steep terrain, rarely use level 4 (or level 5, my 48v has a C3 display with 5 levels of assist). Your description sounds like something is off. Why don't you try with the speed sensor hooked up to see if that makes any difference?

I would be interested in the results of that experiment (as I am too lazy to conduct it myself!)

With my motor, I feel no need of restriction to comply with the law, at least. My fastest speed on flat terrain-- and to be fair, the only flat streets here have stop signs or lights every two blocks at most-- is about 22 MPH. It may have to do with the 42t front chain ring or something, but it feels like physics is not going to allow me to go much faster than that-- like on a runway or drag strip, maybe I could do 24 MPH.

If this is actually true, it's definitely worth it for me to experiment with the smaller narrow-wide 38t chain ring. On paper, in 10th gear, I should be able to hit close to 30, but it may turn out that the real world top speed on flat terrain is 25 with the 42t, and would be more like 27 with the 38. I might have the leverage to maintain a higher cadence.

To keep up with traffic, on a slight downgrade, I can get my bike up to about 25 or 26 MPH, and it is nice that the assist is still stable when riding in traffic. @EMGX, how much does your bike weight? (Sorry if you posted this elsewhere.) I'm also confused-- does your bike actually have five levels of assist, or does it just display five? What happens if you are in level 5?

Thanks! Hopefully, on Tuesday, I'll get a chance to try some crazy sh*t with the rear cluster to improve the chain line. If I could get into first gear, I could use level 2 and 3 more.

 

[EMGX]

The c3 display provides a true 5 levels of assist for the 48v which is all I've used it on. Level 5 on the 48v 750w version provides about the same feel of assist as my Yamaha pw-se equipped gravel bike. 36v 500w version has less max assist but still good. If I had to choose between my two tsdz2 I'd go for the 48v version. I've used them on 6 different bikes ranging from 20" folder to 24" folding dahon briza (wife's) to 26" folding dahon jack to 700c schwinn avenue hybrid to a couple others. Weight depends on battery but the bikes I've weighed after conversion have been 40+# including battery. Prior to conversion 26-28# depending on which bike. For comparison my BH Rebel Gravel X with the yamaha weighs ~41#.

 

[harryS]

I've found that mid drives seem to run better with high gearing and a brisk cadence. They're not happy with slow pedaling and a low gear. Maybe with a 52T front gear, Eco or Tour, the motor is stalling out with the allowable assist levels.
,
I get this watching the brightly dressed riders that pass me, spinning at 60 bpm, with neither of us really going that fast, Seven years of riding cadence ebikes, I was quite used to staying in the smallest 11T gear in back, and pressing harder on the pedals at low speed.

 

[freckles]

TSDZ2B on one of my two bikes, pro install, filled with grease, no sensors or cutoffs. Experimental build, 29'er, 42 pounds, very wide bottom bracket, very wide gear range, chain line issues so 1st gear (52t) is not usable, the crank is 42t. I may wrench on it some this weekend, the builder (Pedaluma) and I have a crazy idea for moving first gear further outside.

No clunky pedaling 'from the start,' and certainly none at PAS 1 or 2. It's generally smooth and very efficient-- I had over 37 miles of range with well over 2,000 feet of vertical on the last charge-- but it does have some odd quirks.

To speak to your specific situation: I did notice, on one ride only, clunking at the same cadence as crank rotation. However, this was at max assistance and max pedal pressure. It sounded like a sound that was coming from 'inside' something. Repeated the same ride the following day, rode the same way, and no problems.

PAS 1 is pretty weak. There is no resistance from the motor while coasting or ghost pedaling, but as soon as the toque sensor engages the motor, it feels like there is some kind of resistance somewhere, so PAS 1 is not much different than 0 PAS. It's like it's +30%, but I've got 20% friction canceling it out, so it's maybe +10%. Note that I probably only recognized this because my other bike has a Shimano E5000 that seems to have no friction in any situation. On the Tongshen, PAS 2 is more usable, probably +50%, PAS 3 close to 100%, PAS 4 is much more powerful-- and there seems to be a 'super power' mode that only engages in low gear when I'm applying a lot of human torque.

So it's funny-- feels like a 50nm motor in most situations in 1 and 2, maybe 60nm in 3, 80nm in PAS 3, and 90+nm in Mystery Climbing Mode.

Pedal will probably chime in... knows a lot more than me. Right now, I'm wondering about your cranks. And to me, 52t is a ginormous chain ring, but there are huge hills where I live, so of course I would think that!

Thank you! I'm hoping PedalUma will chime in as well- he is the TSDZ2B expert!

I had the original 170mm cranks initially and the same clunky pedaling. I switched to 155mm straight cranks b/c the stock angled cranks wide q factor and offset right crank was too wide and uncomfortable. Plus my other 20" bike has 150mm cranks- I'm short and the smaller cranks make for easier pedaling.

The PAS 1 is almost nothing and honestly, just kept it at PAS 2. PAS 2 I feel something and hear the motor but I have to pedal super fast to try and overcome the clunky pedaling which makes it feel like I'm not getting any assist at all if that make sense.

PAS 3 and 4 I found the assist to be smooth and powerful no matter the cadence.

Maybe I'll try swapping out the 52t for the stock...

 

[freckles]

I've found that mid drives seem to run better with high gearing and a brisk cadence. They're not happy with slow pedaling and a low gear. Maybe with a 52T front gear, Eco or Tour, the motor is stalling out with the allowable assist levels.
,
I get this watching the brightly dressed riders that pass me, spinning at 60 bpm, with neither of us really going that fast, Seven years of riding cadence ebikes, I was quite used to staying in the smallest 11T gear in back, and pressing harder on the pedals at low speed.

So confusing- I thought mid drives, especially with the TSDZ2B's smaller motor, likes high cadence low gearing to avoid overloading and stripping out the blue now white gear?
My bike has 9 gears and I down shift to 2 for stops and spin as fast as I can while shifting up to gain speed and to try to overcome the clunky pedaling at PAS2.

But when on PAS 3 and 4, again- all smooth and easy to gain speed.

 

[PedalUma]

Hi, I just stumbled onto this thread with some of my favorite folks.
A 52-T chainring is large and 155 crank arms are small, so @freckles is not getting much leverage. One would think that down shifting would help but I suspect that the torque sensor is not getting the input it needs from the cranks at lower power levels on that build. One thing to experiment with is pedaling backwards while starting the display on the Short Haul. Or rolling the bike backwards at start. Freckles went with a 52 because the wheels are small on the Short Haul. The TS-b does like higher cadence and delivers maximum power at 80 rpm on the pedals. Also, do not focus on pushing down on the pedals. Focus instead on pulling back at the bottom and pushing forward across the top. This will avoid spiking the controller twice per revolution. Ideally pedaling should feel like swimming with scuba flippers and not stopping with clod hoppers. This pedaling technique takes practice. Down shift and rev up before up shifting to a faster gear when accelerating. It is a cool bike.

 

[freckles]

I just came back from a 40 minute bike ride after recharging battery to 80%, about 8 mile total urban riding (potholes, uneven pavement, construction, stop signs, traffic lights, cars everywhere!) so lots of stops/starts, grade going slightly downhill and then uphill on the way back.

I feel the clunky pedaling when I start to pedal or am in too low a gear (and just spinning, need to shift up). When I shift up, it goes away until I hit the max of that gear and am spinning but not fast enough. More noticeable on the slight downhill and needed to shift to higher gears faster to avoid the clunky pedaling.

I noticed this in PAS 2,3 and even slightly in 4. I can overcome it by pressing down a bit harder on the pedals and shifting to higher gear. This gives me smooth pedaling. And I can pedal a bit slower (but still greater than 60) being in a higher gear.

Going uphill, less clunking b/c I'm pedaling a bit harder and reach the max of each gear slower.

 

[freckles]

Hi, I just stumbled onto this thread with some of my favorite folks.
A 52-T chainring is large and 155 crank arms are small, so @freckles is not getting much leverage. One would think that down shifting would help but I suspect that the torque sensor is not getting the input it needs from the cranks at lower power levels on that build. One thing to experiment with is pedaling backwards while starting the display on the Short Haul. Or rolling the bike backwards at start. Freckles went with a 52 because the wheels are small on the Short Haul. The TS-b does like higher cadence and delivers maximum power at 80 rpm on the pedals. Also, do not focus on pushing down on the pedals. Focus instead on pulling back at the bottom and pushing forward across the top. This will avoid spiking the controller twice per revolution. Ideally pedaling should feel like swimming with scuba flippers and not stopping with clod hoppers. This pedaling technique takes practice. Down shift and rev up before up shifting to a faster gear when accelerating. It is a cool bike.

View attachment 164359

Hello PedalUma!
I will try starting the display while pushing the pedal backwards or rolling bike backwards and report back.
Might swapping the 52T to original help too? I thought I wanted a 28mph capable ebike but now second guessing the safety of riding at 28mph on 20" wheels on crappy LA roads...

I posted earlier that I noticed when I pedal a bit harder in higher gears, the pedaling is smooth, no clunk. I'm not stomping but am pushing harder than flipping ankles. But maybe I'm just in the right gear vs too low a gear?

I've been practicing and consciously try to flip my ankles while pedaling but when I'm in too low a gear, I get no traction so I'm practicing shifting to higher gears faster on my ebike. I find it easier to flip my ankles and shift on my regular pedal bike for some reason???? It maybe b/c the feedback is immediate with no filter (assist).

PAS 4 is amazing and the torque is super powerful- At gear 2 at a stop light, it felt like the front wheel came up a little at the start of pedaling!

 

[PedalUma]

That is cool when you catch a little air launching a cargo bike! If you try the 42 ring, first try it in the lowest gears. If that looks, feels promising, then remove links from the chain and try it in all gears. I think you are right about doing 28. The idea sounds better than it is in reality. 18-22 mph is nice. I saw a collision speed/mortality chart for pedestrians hit by cars. The same would apply to hitting a curb, parked car, or USPS mail box at speed. I don't want to be in an emergency room. My buddies go 40 down hill on rural roads with rusted barbed wire at the side of the road.

 

[PedalUma]

I just received this photo that you folks might enjoy. @Catalyst, I have been thinking about your battery. I think that you could charge to 100% just before a ride about once per quarter to balance the cells, given how much your ride. The photo is from Mount Tam where modern mountain biking was invented. It went from downhill clunkers in '78 to bikes like this 1982 Ritchey that could climb.

 

[Kayakguy]

I added a Tongsheng mid drive to a Tern Short Haul bike- its a 20" wheel, changed to a 52 front chain ring and 155 mm straight cranks. Not using speed sensor or brake cut offs.

This is my first ebike, first mid drive.

Noticed "clunky" pedaling from the start. The best I can describe it is- some resistance then feels like it slips when pedaling=clunky, on PAS 1 and 2.
At a higher pedaling cadence, it improves somewhat but still feels a bit "clunky".

I thought this is how it just is but very recently tried PAS 3 and 4- what an amazing difference! No more clunky pedaling no matter the cadence. Just smooth pedaling and incredible bionic legs!

I understand PAS 1 is minimal assist and imagined I would mostly be at PAS 2 with occasional 3 and 4 for boosts but the pedaling is so smooth at the higher PAS levels I don't want to go back.

For those with stock Tongsheng experience- do you experience some pedal clunkiness on PAS 1 or 2 too and just ride at higher PAS levels?

No, I have noticed no clunkiness at lower PAS levels; in fact, mostly I ride in PAS 1 or 2. Bike is an Ariel Rider C class with a Tongsheng motor and Nexus 7 IGH. I do try to maintain a cadence in the 70 rpms (for which I use PAS minimally, but mostly gear selection). It may be relevant that I am a really old guy (like 86 yo). Maybe e the clunkiness of knees and hips drowns out the clunkiness of the motor, though.

 

[Catalyzt]

My "clunk" when pedaling has not returned so far, so so good.

I finally got to a flat (and mostly deserted) bike path with no stop signs or lights. (LA River). The Marin build can hit 25.5 if I really pour it on, 24.5 is easier to maintain. Oddly, 24.5 seems as easy to maintain in Level 3 as Level 4, but I have to double check that.

I think with faster-rolling, slightly narrower tires, it could probably hit 27 on the flats, maintain 26.

 

[PedalUma]

27 on the flats

We calculated 28 but that was static gearing and did not account for wind resistance which goes up. 40kph is about 28mph. Someone did find a creative way to eliminate rolling resistance.

https://rollingrouleur.tumblr.com%2Fpost%2F79975426291