TSDZ2 speed restrictions

[neilhapgood]

Hi folks,

so I have just fitted the 48v 500w motor to an old mountain bike, with a 48v battery, I am using it to pull a bike trailer with kitesurfing equipment in to the beach.

The pull is amazing, even uphill it powers up with a heavy trailer.

However I can't seem to get it to go faster than 18mph on the flat, it feels like it gets that fast and then just stops trying.

I have changed the upper speed limit to 45kph and also lied about the wheel size so it reads a far lower speed than you are actually going, however I still can't get it to go any quicker. Even standing out the saddle and putting as much force through the pedals as I can it won't kick in at that speed and go quicker.

Is this normal for this motor on the flat?
Anything I can do about it?
Is there anyway to check what motor I have in case I was sent a slower one?
Would having a throttle help?

any help hugely appreciated!

many thanks

 

[vfr400]

That's normal if you have a 201 rpm motor. All motors have a maximum speed depending on their windings and the battery voltage. No matter how much power you give them, you can't make them go any faster. If you had bought a faster motor, it's efficiency when climbing and/or towing would be worse, so you'd get less range and a higher chance of overheating the motor and controller.

 

[MontyPAS]

Think you can get around the speed restriction with the "Open Source Firmware".

OpenSource-EBike-firmware/TSDZ2_wiki

Contribute to OpenSource-EBike-firmware/TSDZ2_wiki development by creating an account on GitHub.

github.com

Ive got a TSDZ2 in a box, was going to try installing the firmware, but the instructions are so disjointed / complicated, may just put it on a plodder bike for the wife with the stock FW.
TBH prefer the flexibility of the Bafang BBS02b

 

[sjpt]

That's normal if you have a 201 rpm motor. All motors have a maximum speed depending on their windings and the battery voltage. No matter how much power you give them, you can't make them go any faster. If you had bought a faster motor, it's efficiency when climbing and/or towing would be worse, so you'd get less range and a higher chance of overheating the motor and controller.

If you power the motor with the drive wheel off the ground you can verify if that is the issue; the motor will hit a no-load speed.

 

[vfr400]

You don't say which motor you bought. I assumed a hub-motor. If you bought the crank-motor that you planned to, the motor still has a maximum speed (crank-rotation speed), but you can change the bike's speed by altering the gearing;however, bear in mind the cost in efficiency and heat. The TSDZ2 is not a particularly robust motor, so be careful about over-loading it with tall gearing.

 

[neilhapgood]

Hi all,

thank you so much for the replies, it is a mid drive motor.

Vfr400 that makes a lot of sense, as you said I was wondering if I could get around it with a 52t chainring?

If a 52t chainring would help It sounds as though I would have to be careful in terms of overloading, can I limit the danger of this by taking my time accelerating and only pushing for top speed on the flat what I already have good momentum, or does it not work like this?

Also does riding a short distance (7.5 miles to the beach!) prevent overloading or is it not a case of overheating but overloading in the moment so to speak?!

Thanks again

 

[MontyPAS]

Hi all,

thank you so much for the replies, it is a mid drive motor.

Vfr400 that makes a lot of sense, as you said I was wondering if I could get around it with a 52t chainring?

If a 52t chainring would help It sounds as though I would have to be careful in terms of overloading, can I limit the danger of this by taking my time accelerating and only pushing for top speed on the flat what I already have good momentum, or does it not work like this?

Also does riding a short distance (7.5 miles to the beach!) prevent overloading or is it not a case of overheating but overloading in the moment so to speak?!

Thanks again

The weak link of the TSDZ2 is the blue nylon drive gear in the unit, possibly there as a safety device, to save the motor when overload by excessive owner use. Looks easy enough to change, but a pain nonetheless.
52t chain-ring could put quite a strain on the motor if in the wrong gear on the cassette, whilst attempting a steep incline?

 

[vfr400]

52T sounds a bit high to me. What do you have as a top gear at the back?

 

[neilhapgood]

Its a 9 speed cassette at the back, the biggest one has 32 teeth, I think, lost count a few times!

I don't need to get much more speed, only a few mph, however I also prefer cycling with lower cadence and a bit more effort than high cadence. The cycle I use the bike for is flat all the way.

Would 48 or 50 teeth be better do you think?

As always many thanks for the help

 

[vfr400]

Unfortunately with a crank motor, you're not master of your own destiny regarding cadence. I think your motor is 90 rpm max, so you need to pedal at about 70 rpm for best power and efficiency. 60 rpm should still be OK, which is fairly leisurely. I wouldn't want to go any lower than 50 rpm.

You've given the bottom gear size, but it's the top gear that controls your maximum speed. So, how many teeth on the top gear and how many on your chainwheel? From that, we can work out your cadence.

 

[neilhapgood]

amazing thanks, small one is (i think) 12 and front one is 42.

thanks!

 

[vfr400]

12/42 will give 16 mph at 60 rpm with a 26" wheel. Your motor would max out at about 80 rpm on the road, which would be about 21 mph. You need to check that top gear. Maybe it's 13T, in which case a normal 11/32 cassette will solve all your problems.

 

[neilhapgood]

amazing thanks vfr400, it was a 13t so loaded up the trailer and popped to my bike shop who changed the cassette and chain and it is now better, reaching 20 - 22mph with a fully loaded trailder, only concern now is if the motor is gettting too hot, will starrt another thread for that!

thanks again, great help, really appreciate your time

 

[vfr400]

amazing thanks vfr400, it was a 13t so loaded up the trailer and popped to my bike shop who changed the cassette and chain and it is now better, reaching 20 - 22mph with a fully loaded trailder, only concern now is if the motor is gettting too hot, will starrt another thread for that!

thanks again, great help, really appreciate your time

Remember high cadence keeps it cool. You didn't change the gearing of the lower gears, so it should be OK when climbing. My worry about a bigger chainwheel was that it would raise bottom gear and make hill-climbing harder. If in the end you can't pedal fast enough going up steep hills when fully loaded in bottom gear, you'll need to get a cassette with a lower bottom gear, like 11/36 or even 11/40 if your derailleur can go that big.

You have to practice pedalling faster. It's easy when you have a motor to help, and it doesn't take long to get used to it if you keep trying. It's just a bit weird at first. Don't go nuts. You need to aim for about 70 or 75 rpm. Some cycle computers can give you your cadence or you have to count pedal strokes per minute until you get a handle on what that speed feels like.