Expected top on the flat speed out of a 250w/350w bafang midrive please?

[phil sommerton]

Hi,

Before I commit to buy I have a question for you good people..could i get 20mph out of a 250w/350w bafang mid-drive please? I weigh 14 stone, have a 29er giant revel and was going to drop the wheel size in the display to up the speed a touch from the 15mph limit. I guess I was ultimately hoping for 20mph+ on the flats (all of my commute is flat luckily) as I can do 15 easily myself. What do you guys who have this setup think? Was thinking of an 8ah 36v hour pack for my 10 mile each way commute so if you guys can post your ranges that would confirm the size of pack also and help me a lot
Thanks,
Phil

 

[soundwave]

will do that easy if you get the programme cable you can up everything but will need more amps and a bigger batt to do so.

or the range will not be much at faster speeds.

a 1000w bafang hd will do over 50mph.

 

[Geebee]

You can leave the wheel size as correct and just turn the speed limit up, easily done through the display.
Short answer about speed is yes easily , long answer below.

I ride a recumbent trike with a BBS01 and it will just make 40 kph (24,.8 mph) uses between 7~8 wh per km on the flat without pedalling but there are some proviso's the trike weight battery included is 19.5 kg and I weigh 70 kg, it is running racing slicks and is about as aero dynamic as a road bike with a Lycra clad rider on the drops, the BBS01 likes to spin as it is more efficient so a higher cadence reduces the wh per km.

I also have a Tonaro Esprit (dutch city bike style) and even when unfit I could easiy maintain the speed you want with a drive very similar in operation to the BBS01, speed was not controller limited as it fell into the 200w rating.

Range is so rider and terrain dependent it is close to impossible to give a reliable range.
With the information you give re unassisted speed I think 8 ah would work easily but personally I would go 10ah, the pack will last longer as the level of discharge is lower and if you need to take a detour you will be covered.
Just make sure you do a ride or two locally before the first commute my Tonaro's range doubled after the second charge.

Before becoming ill I allowed for upto a 60 to 80 km range on a 10ah 36v pack on most of my bikes in what most would class as hilly terrain but I like pedalling, the only time I got caught with out on range was the first charge on the Tonaro

 

[D8ve]

As Geebee said its your effort and bike performance.
I can get over 20 without assistance on the flat as my bike is very aerodynamic . With assist well 30 would be possible but I stay legal.
With cut out at 15 I get well over 100 miles from a 16ah battery. Or 20 from a 3ah pack.
To maintain a 20 mph average on the road you need no traffic, lights or junctions. Add these in and your ave speed drops very quickly.
As you can do 15 already 20 would be easy for you with assist. And the range but tires and aero are more important now.

 

[phil sommerton]

thanks for the replies..soundwave, i really wanted to stick with the 250w or 350w to be at least near legal.i'll probably paint over the wattage anyway so maybe 500w max. all based on the speed people would tell me i can achive with each roughly. Thanks Geebee Though I forgot to to say I'm only using pas mode as i like to pedal if that makes any difference thanks..just trying to not be so sweaty getting into work and cutting my 35-40 min commute down but still pedaling a decent amount, maybe half the effort would be nice. Dave,. good info. It will be all cycle path unassisted thanks and flat with say 50% effort? so glad to hear 20 is doable with a 250w and more if above? tires are 32c specialised nimbus semi slick so not bad rolling

 

[jwm]

With the PAS, you basically pedal as much as you want to, with the BBS01 it just about getting the right gear and power setting you want to shove through it. I've just put one on my Tern and it will achieve everything you want. I'm not as heavy as you, though I carry lots, laptops, shopping plus other gear so you should be fine. With the battery go for the biggest you can afford relative to the extra weight of carrying... you will always want more and carrying a spare can be a pain, if you ever get round to actually buying one (I know from experience) .

John

 

[soundwave]

as you can change the settings on all of them none are uk road legal as deemed to have a off road switch.

250w or 10000w it does not matter the police wont do anything so just get what you want power wise and put 250w on it if you want.

 

[Nealh]

I did have a 350w bbs on my mtb until the controller went t*ts up, 18mph was my cruising speed in assist 5 or 6 so bang it up to 9 and 20 is no problem on the flat but the battery range will suffer. New controller arrived form China and now fitted and all working, have fitted 250w controller and may get a programming lead to play with settings.

 

[D8ve]

The 250 watt rated motor is legal as that's what the manufacturer calls it.
But they can run at near 700watts still legal. 42volt x 18 amp ?
They can be reprogrammed, via the control panel. It's not what they call an off-road switch so it stays legal until you set the speed to over 26 kph then if they look closely you have a unlicensed moped.
That's a risk you have to take. Keeping legal is worth an estimated £20,000 £10,000 for expenses and £10,000 for injuries to me. The drivers mate tried to test my brakes when they had just broken my arm with a 4*4 ! But the police did them for careless driving.

 

[phil sommerton]

many thanks guys. good info here. I've just ordered based on your info. Next step is to build my battery pack up. those years of rc car racing electrics coming in handy for something.

 

[LeighPing]

many thanks guys. good info here. I've just ordered based on your info. Next step is to build my battery pack up. those years of rc car racing electrics coming in handy for something.

So, what did you order then Phil?

 

[phil sommerton]

Hi. I ordered the 350w to give a little amperage headroom in case of future requirements changing. I will un-mark the motor however or sticker over as a 250w. good news is also that my friend who has an MOT garage has a spot welder. bonus!