250w kit with torque

[slowbutsure1936]

Hi,

I want to get a legal 250w conversion kit but I want one that will do the best possible job up hills. Im fairly heavy (16 stone).

I have a 48v battery 20ah. Can anyone recommend the best conversion kit for hills?

Many thanks,

Trevor

 

[Nealh]

It depends what the continuous current out put of the battery is, this controlled by the BMS. The peak out put is no good it has to be continuous, then a controller kit could be recommended.

 

[slowbutsure1936]

It depends what the continuous current out put of the battery is, this controlled by the BMS. The peak out put is no good it has to be continuous, then a controller kit could be recommended.

Not sure I fully understand your question. A 48v battery at 250w is 5amps (roughly). Lets assume then that this is 5 continuous amps?

 

[slowbutsure1936]

It depends what the continuous current out put of the battery is, this controlled by the BMS. The peak out put is no good it has to be continuous, then a controller kit could be recommended.

in any case I would get a different battery if needed. The kit is the priority.

 

[Nealh]

Not sure I fully understand your question. A 48v battery at 250w is 5amps (roughly). Lets assume then that this is 5 continuous amps?

In that case one doesn't understand how epac power/current ratings are calculated.

 

[slowbutsure1936]

In that case one doesn't understand how epac power/current ratings are calculated.

one is correct. I’m not sure if you are trying to be helpful or not. Regardless of the battery (o can get a new one), do you have any suggestions on a 250w kit that is best for up hills?

 

[matthewslack]

Hi,

I want to get a legal 250w conversion kit but I want one that will do the best possible job up hills. Im fairly heavy (16 stone).

I have a 48v battery 20ah. Can anyone recommend the best conversion kit for hills?

Many thanks,

Trevor

Define the worst case hill you need to get up, steepness and length, and give an idea of whether you need the motor to do all the work, or how hard you want to work on hills, and any limitations e.g. bad knees...

 

[Nealh]

All 250w motors can output much more wattage so one needs to know the motor controller rating to recommend a suitable battery for the motor.
For instance some 36v kits can out put 900w, whilst some 48v can output a bit more. These higher wattage outputs are a temporary output which is allowed as the 250w is only a continuous motor rating.

 

[slowbutsure1936]

Define the worst case hill you need to get up, steepness and length, and give an idea of whether you need the motor to do all the work, or how hard you want to work on hills, and any limitations e.g. bad knees...

I don’t know all or even most of the places I will decide to cycle to in the future, so can’t really define that. Suffice to say I am looking for the best 250w kit for hills available in the U.K. there must be one or two in that category? My knees and health are fine. Thanks.

 

[Bonzo Banana]

What is the bike you are converting to an ebike and does it have decent low gearing? I think Mr average produces about 50Nm of torque over an extended period but a weaker rider could be around 30Nm and then you have the gear ratios on the bike and the different motors. I think a direct drive hub motor at legal power output is probably around 30Nm torque, a geared hub motor (larger type) perhaps around 45Nm max at 250W nominal and a mid-drive motor in a kit maybe peaks around 85Nm maybe a bit less continous torque like 60Nm. Mid drives have their power scaled through the gears so can have some advantages to hill climbing but all ebikes make hills a lot easier with the possible exception of single gear ebikes with low powered hub motors that might struggle a bit. Depending on your weight and power I guess you could say an ebike gives you 2-5x your normal power climbing hills allowing for all the variables and that is just a guesstimate without much science behind it. Some smaller hub motors can't dissipate heat that well so may struggle a bit on long steep climbs, cut out etc but if you are putting in reasonable effort yourself shouldn't be an issue.

16 stone is about 100kg I think so no big issue for many ebikes if you are assisting the motor. I think my violamart direct drive hub motor is rated to a maximum of 200kg and the small geared version is still rated to 100kg that was the other choice at the time. Mid drive motors are typically the weakest motors for reliability and wear and tear as the most complicated however are also the best motors for climbing steel hills.

I'm heavier than you and went with direct drive but at your weight all 3 options are decent options when choosing a ebike kit.

 

[Nealh]

48v kits are rare Woosh bikes sell the tsdz2 mid drive or a rear wheel hub kit, also risunuk sell a 48v 250w tsdz2.
Other wise for 48v kits one has to buy form china vendors as separate components albeit form the same pages.
Probably the most capable 250w kit is 36v 25a BBS01etm.

 

[slowbutsure1936]

48v kits are rare Woosh bikes sell the tsdz2 mid drive or a rear wheel hub kit, also risunuk sell a 48v 250w tsdz2.
Other wise for 48v kits one has to buy form china vendors as separate components albeit form the same pages.
Probably the most capable 250w kit is 36v 25a BBS01etm.

thanks, who makes the BBS01etm ?

 

[slowbutsure1936]

What is the bike you are converting to an ebike and does it have decent low gearing? I think Mr average produces about 50Nm of torque over an extended period but a weaker rider could be around 30Nm and then you have the gear ratios on the bike and the different motors. I think a direct drive hub motor at legal power output is probably around 30Nm torque, a geared hub motor (larger type) perhaps around 45Nm max at 250W nominal and a mid-drive motor in a kit maybe peaks around 85Nm maybe a bit less continous torque like 60Nm. Mid drives have their power scaled through the gears so can have some advantages to hill climbing but all ebikes make hills a lot easier with the possible exception of single gear ebikes with low powered hub motors that might struggle a bit. Depending on your weight and power I guess you could say an ebike gives you 2-5x your normal power climbing hills allowing for all the variables and that is just a guesstimate without much science behind it. Some smaller hub motors can't dissipate heat that well so may struggle a bit on long steep climbs, cut out etc but if you are putting in reasonable effort yourself shouldn't be an issue.

16 stone is about 100kg I think so no big issue for many ebikes if you are assisting the motor. I think my violamart direct drive hub motor is rated to a maximum of 200kg and the small geared version is still rated to 100kg that was the other choice at the time. Mid drive motors are typically the weakest motors for reliability and wear and tear as the most complicated however are also the best motors for climbing steel hills.

I'm heavier than you and went with direct drive but at your weight all 3 options are decent options when choosing a ebike kit.

I have a Carerra Subway.

 

[Nealh]

BBS are Bafang/8fun produced. The ETM is extra torque model 15a is the std 250w BBS01, where as the 18a model is 350w marked.

 

[matthewslack]

I don’t know all or even most of the places I will decide to cycle to in the future, so can’t really define that. Suffice to say I am looking for the best 250w kit for hills available in the U.K. there must be one or two in that category? My knees and health are fine. Thanks.

A mid-drive like the Bafang gives you the flexibility to modify the chainring and cassette to get up any hill you need to, with the motor doing most of the work.

A hub drive gives you the flexibility to modify the chainring and cassette to allow you to coax the motor up hills too steep for it to manage without your help.

For no limits to hill climbing in the 250W legal power range, @Nealh is spot on. The Bafangs allow a smaller chainring than the TSDZ2, so lower gearing with a given cassette, and if you choose the rear derailleur to suit you can go up to 50T on the rear. Not capable of vertical takeoff, but getting close.

 

[Bonzo Banana]

I have a Carerra Subway.

Perfect bike for any ebike conversion really, strong aluminium mountain bike frame with chromoly steel forks and strong 26 or 27.5" wheels depending on age of model. If it was a Carrera Subway 8 (Nexus 8 rear hub) you couldn't do a rear hub conversion and you shouldn't do a mid-drive conversion either on those but that is the only possible limitation and you haven't mentioned that so presume its just a standard Subway with a standard mountain bike style drivetrain with cassette.

 

[Nealh]

Pretty sure if one puts there mind to it a 32t CR could fit on a tsdz2.
My plan is to try a double front set up the same as i had on the BBS, if not I shall opt for 36t single for my towing.

 

[matthewslack]

Pretty sure if one puts there mind to it a 32t CR could fit on a tsdz2.
My plan is to try a double front set up the same as i had on the BBS, if not I shall opt for 36t single for my towing.

I'd be interested in anything smaller than the std 42 - first impressions out of the box suggested poor chainline if the chainwheel wasn't dished over the drive casing, and a bigger drive casing than Bafang.

When I'm back from Wales in late April, that box will be implemented, and then I'll know for sure!

 

[guerney]

Pretty sure if one puts there mind to it a 32t CR could fit on a tsdz2.
My plan is to try a double front set up the same as i had on the BBS, if not I shall opt for 36t single for my towing.

If you decide to go that route, I'd be very interested in seeing how you install a double chainring and shifter on your TSDZ2, because I have recurring fantasy of adding a 60T to the existing 52T on my bbs01b. I really should not do it, because it's already a bit fast...

 

[Nealh]

I have had a double on the BBS on two bikes and the derailleur shifted fine on the front, for the BBS one can buy a spider adapter for the rings. I had to add a washer between the inner ring fixings for chain gap.
I haven't got the TSDZ yet but believe it uses std 104bd spacing for the chain ring.