Help! Advice on replacing Gears

[Jaxter]

Hi all i have an carerra Centos 13. brought for a bafang mid drive conversion, after giving the bike a test ride pre-conversion, i have decided i would like to strip it of existing 3x8 gears and to simplify things by going between 1x8 to 11.
I think i'd like to have all new parts so could someone tell me the parts i'll need, as a cycling novice an explanation of what different chain ring sizes do would be appreciated to.
Thanks

 

[vfr400]

What are you going to use the bike for and exactly which motor are you going to fit?

 

[Jaxter]

What are you going to use the bike for and exactly which motor are you going to fit?

Bafang bbs02 s the motor, and mainly commuting and light trails,

 

[vfr400]

Bafang bbs02 s the motor, and mainly commuting and light trails,

Too vague.

 

[Jaxter]

Too vague.

what more informatoin would you like

 

[vfr400]

what more informatoin would you like

How heavy you are, what sort of hills you want to climb, what cadence you want, how fast you want to go which BBS02 you're going to fit, what you're going to program the current to, how hard you want to pedal, etc.

 

[Jaxter]

Ok, lets start with the easy one im 18st, and its the bbs02 48v 750w, is what i'll be fitting paired with a 17ah 48v battery.
Im no speed demon, so will pootle around mainly in the lower assist levels i would imagine, as for pedalling i dont want to pedal too hard as im really starting to feel the strain in my knees. but minor resistance on the pedals would be nice.
There are not too many hills in my neck off the woods, but there is one that is on my home route that is a proper bugger and at times i traverse it 2-3 times a day, i also think i'll be exploring further out so im sure i'll encounter more challenging terrain.
As to how i'm going to program the current i suppose once u and running i would see how it all behaves and take it from there but i would guess whatever gives me torque on the steeps for climbing when really needed, rather then speed.

 

[vfr400]

OK. I have the picture now. I think you're wasting your money buying expensive gears that are going to wear out quickly. They're only necessary if you want that extra edge for off-road riding or if you had a road bike and were trying to save weight. basically, they give you high torque for climbing and high speed, but if you don't want the high speed, it's a waste.

A 750w BBS02 should be able to get an 18st rider up any hill with normal 8 speed gears - say 11-34.

Say you had 11/44 top gear. The BBS02 makes it's best power round about 70 rpm, so that would give you 280 rpm at the back wheel which is a comfortable speed of around 21 mph and a top speed of around 24 mph.

Bottom gear would be 34/44, so at 70 rpm, you get 96 rpm at the back wheel, which is 7 mph. You can still get useful efficiency and power down to around 50 rpm, which would be 5mph. If you went much slower, you'd probably fall off.

It sounds about right to me. Have you tried it yet?

After that, you could get a Lekkie Bling Ring of 42T or 40T if you feel you want to trade speed for more torque to get up the hills.

 

[Jaxter]

Firstly thanks for taking the time to give such an in depth answer and sharing your knowledge with a novice, much appreciated.
I should have been more clear in my post, i am not wanting new gears for any real performance upgrade or weight saving.
The reason is the current gears are just performing crappy, crunching, creaking, and clicking and kind of hit and miss, to be expected of a well used second hand bike i suppose.
So after what has turned into a considerable investment, my thinking is to simplify the amount of gear changing by reducing the amount of gears, and to have a smooth shifting bike that can better cope with the rigours of the motor and especially not having the chain fall off every 5 minutes.
I dont want to spend the earth, but will stump up what i have to, would i be correct in thinking whats needed is an 11 speed cassette, 11 speed chain, a narrow wide toothring. and a clutch deraileur, also 11 speed shifter.
This is what i have gleaned from the youtube vids i have watched on the subject, welcome to steer me right if i have got it wrong.
Thanks

 

[Raboa]

Another option could be to buy a BBS02 adapter that allows you to run two chainrings.
Buy a new chain, cassette and rear derailleur for your current system.

 

[Jaxter]

Another option could be to buy a BBS02 adapter that allows you to run two chainrings.
Buy a new chain, cassette and rear derailleur for your current system.

I shall look into this option, thanks

 

[vfr400]

For a 750w BBS02, you need strong and robust gears rather than fancy gears, unless you don't mind spending loads of money on replacement parts.

If your gears are crunching, get a gear sensor.

 

[Jaxter]

For a 750w BBS02, you need strong and robust gears rather than fancy gears, unless you don't mind spending loads of money on replacement parts.

If your gears are crunching, get a gear sensor.

Hi vfr400, i am not looking for fancy gears or shifting, just a simplified robust solution.
The bike hasn't been converted yet, i wasn't happy with the gears as they are, so thought whilst converting i may as well get it all into a condition im happy with.
I have got a gear shift sensor i intend to fit as well.

 

[vfr400]

Hi vfr400, i am not looking for fancy gears or shifting, just a simplified robust solution.
The bike hasn't been converted yet, i wasn't happy with the gears as they are, so thought whilst converting i may as well get it all into a condition im happy with.
I have got a gear shift sensor i intend to fit as well.

Try it first, then, if you find any shortcomings, figure out the solution you need to make things better. Don't try to solve problems that don't exist.