im new to ebikes , ive got a gt comp aggressor with a 34tooth chain i dont really understand all the cassetes and teeth and that but im looking at buying a bbs02b mid drive kit. on the website when i have selected a battery ( bb100mm, 44t +48v20 downtube battery ) it says 44t which im pretty sure means 44tooth chain but my chain is only 34tooth and it climbs uphilll quite easily its shimano gears its got 7 gears on the right of the handle bar and on the left of the handlebars theres 3 gears im not sure what they do so do i need to buy a 44tooth chain for my bike and will it fit on bearing in mind when i bought the bike new it was a 34tooth and still is?

The t is how many teeth the chain wheel has , teeth = gearing. Less teeth = easier pedalling or faster cadence up to a point, then you are into over rotation and unable to pedal any faster.

The chain is sold by links , one doesn't buy a 34t chain or a 44t chain, one has to but a chain by links and then sometimes has to either add more links or remove links for a correctly fitted chain length.

i have selected a battery ( bb100mm, 44t +48v20 downtube battery )

That's making me nervous. What's the BB100mm?

BB is bottom bracket, this is the part of the frame that the crank arm spindle goes through. Measure your frame bottom bracket and check the kit will fit (most people have no problem).

BB is bottom bracket, this is the part of the frame that the crank arm spindle goes through. Measure your frame bottom bracket and check the kit will fit (most people have no problem).

how should i measure that im not really technical with bikes haha most my mates have got rons ( surrons ) and im on a pedal bike so its annoying to keep up with them so an ebike is good for me but how would i check it idk how to take the pedals of and all that

The t is how many teeth the chain wheel has , teeth = gearing. Less teeth = easier pedalling or faster cadence up to a point, then you are into over rotation and unable to pedal any faster.

The chain is sold by links , one doesn't buy a 34t chain or a 44t chain, one has to but a chain by links and then sometimes has to either add more links or remove links for a correctly fitted chain length.

the chain ive got is about 3 years old and at the back where the gears are and the pedals too alot of the paint has came of by vicious scratch marks from the chain or something is it because its not lubed? and when im changing gears sometimes it takes a few seconds but it sounds like its grinding sometimes. and how do i buy links or whatever i dont really understand that is there another way you can put it to me in a more simpler way thanks

If your not good at maintenance , you have to either learn to maintain your own bike, ask your mates (if they have any knowledge ) or let a bike shop do it. The first option is most rewarding and cheapest though you will need soem basic tools and be willing to learn.

 

Any paint missing form the frame is down to very poor deraillieur adjustment, gears adjustment over riding causes the chain to jump/travel to far and grind in to the rear drop out /frame.

There are videos about installing the BBS motors, immsmr on the woosh website.

To add further to your troubles, if your chain is 3 years old it will be worn, the rear cogs will be worn too and won't take kindly to a new chain, the rear cogs block will need replacing too. Have a look at Park Tools vids on Ytube, search for Sheldon Brown , lots of good info there too. Give it a go, you can always take all the bits in a box to the local bike shop.

If your not good at maintenance , you have to either learn to maintain your own bike, ask your mates (if they have any knowledge ) or let a bike shop do it. The first option is most rewarding and cheapest though you will need soem basic tools and be willing to learn.

 

Any paint missing form the frame is down to very poor deraillieur adjustment, gears adjustment over riding causes the chain to jump/travel to far and grind in to the rear drop out /frame.

so poor derailleur adjustment ad gears adjustment is completely out of my control and i cant help it or can i?

There are videos about installing the BBS motors, immsmr on the woosh website.

To add further to your troubles, if your chain is 3 years old it will be worn, the rear cogs will be worn too and won't take kindly to a new chain, the rear cogs block will need replacing too. Have a look at Park Tools vids on Ytube, search for Sheldon Brown , lots of good info there too. Give it a go, you can always take all the bits in a box to the local bike shop.

my chain is 34tooth idk if i cant change that but the bbs02b kit im buying says somethig about it being 44t i said about it for my first question you can look up there but if im changing the cogs can i ask for bigger cogs so i can make it from a 34tooth to a 44tooth?

You are getting confused with the terminology. You keep saying chain when you are referring to chain wheel. The cogs are situated on a cassette mounted on your back wheel.

 

For simplicity the more teeth you have on your chain wheel at the front, the higher your gear ratio is. And the more teeth you have on your cog at the back, the lower your gear ratio is.

 

Your first post eludes to a 3 ring chain wheel. This will need to be removed in order to fit the motor, which only has a one ring chain wheel.

 

As you are fitting a motor you can have a bigger chain wheel it will help you assist. So a 44 tooth front chain wheel instead of 34 teeth should not be a problem.

 

You have to remove your pedals, chain wheel, cranks and bottom bracket to fit the motor and then refit the pedals to the new cranks that are supplied with your kit, which comes with a new chain wheel.

 

Here is a link to a calculator that you can use to determine your speed and other things with various combinations of chain wheel sizes and cogs. All you have to do is count up the teeth on each cog in your cassette and plug the numbers in. It will tell you your ratio and speed in each gear at various cadences.

 

Cadence is defined as the number of revolutions your pedals make per minute. And you can increase your cadence with a motor so you can ride faster for longer.

 

https://www.bikecalc.com/speed_at_cadence

 

Here is a good video of how to fit the kit to your bike. But it does not show you how to remove your pedals, crank or bottom bracket.

 

Edited May 9, 20232 yr by AGS

You are getting confused with the terminology. You keep saying chain when you are referring to chain wheel. The cogs are situated on a cassette mounted on your back wheel.

 

For simplicity the more teeth you have on your chain wheel at the front, the higher your gear ratio is. And the more teeth you have on your cog at the back, the lower your gear ratio is.

 

Your first post eludes to a 3 ring chain wheel. This will need to be removed in order to fit the motor, which only has a one ring chain wheel.

 

As you are fitting a motor you can have a bigger chain wheel it will help you assist. So a 44 tooth front chain wheel instead of 34 teeth should not be a problem.

 

You have to remove your pedals, chain wheel, cranks and bottom bracket to fit the motor and then refit the pedals to the new cranks that are supplied with your kit, which comes with a new chain wheel.

 

Here is a link to a calculator that you can use to determine your speed and other things with various combinations of chain wheel sizes and cogs. All you have to do is count up the teeth on each cog in your cassette and plug the numbers in. It will tell you your ratio and speed in each gear at various cadences.

 

Cadence is defined as the number of revolutions your pedals make per minute. And you can increase your cadence with a motor so you can ride faster for longer.

 

https://www.bikecalc.com/speed_at_cadence

 

Here is a good video of how to fit thr kit to your bike.

 

thanks alot! when you said 'Your first post eludes to a 3 ring chain wheel. This will need to be removed in order to fit the motor, which only has a one ring chain wheel ' on the left of the handlebar there are gears there , 3 to be precise is that a ring chain wheel? so when i buy the bbs02b kit i need to make sure the bottom bracket fits 100mm and i need to get a new chain and cogs as they are both worn and old and thats it or do i need to buy a one ring chain wheel. and does it matter what chain i get, can i just buy the exact same chain with the bike as i have found the specs for it online or do i need a certain chain size and rear cog?

The very first thing you need to do is measure your bottom bracket using a tape measure or ruler.

 

Then you can order the correct size motor for your bike.

 

You may have a 68mm, 73mm, 100mm or even 120mm bottom bracket.

 

A 68mm motor will not fit on a bike that has a 100mm bottom bracket.

 

Here is a video of how to do this. And notice that he a has a 3 ring chain wheel on his bike, so you can compare it to yours.

 

I think you should search around on YouTube and watch some videos to learn some basic bike mechanics.

 

Special tools are needed to fit a BBS motor and to change the cassette, although if it’s only 7 cogs on the rear it’s likely to be a freehub.

 

Maybe it would be better if you can find a local bike mechanic to fit the motor for you.

i

The very first thing you need to do is measure your bottom bracket using a tape measure or ruler.

 

Then you can order the correct size motor for your bike.

 

You may have a 68mm, 73mm, 100mm or even 120mm bottom bracket.

 

A 68mm motor will not fit on a bike that has a 100mm bottom bracket.

 

Here is a video of how to do this. And notice that he a has a 3 ring chain wheel on his bike, so you can compare it to yours.

 

ive watched it, my bottom bracket is 3inches so 76mm, am i best going to 100mm ?

I just looked up your bike and it is a 21 speed with a 3 ring on the front. It’s also an ordinary hard tail MTB, so likely to have a 68mm bottom bracket. You need to measure it before buying the motor.

 

The cassette or freewheel and chain can be changed later. The hard part is fitting the motor.

 

You have to measure the frame width only. It won’t be 76mm.

 

It will be 68mm or 73mm you have to measure accurately. If it is 73mm, a 68mm kit will fit, but will need spacers. 100mm will not fit.

The OP is in way over their head as this stage, when it comes to bike components and terminology he or she has liitle/no idea what so ever with maintenance let alone a conversion.

I hate to be so blunt but at this stage it is the truth.

Edited May 9, 20232 yr by Nealh

so poor derailleur adjustment ad gears adjustment is completely out of my control and i cant help it or can i?

 

Derailleur adjustment is in the hands of the user, one is best to search and look at videos to see how to make adjustments .

On the rear of the deraillieur there are two adjuster screws one mark H for high gear and one marked L for low gear these when adjusted determine how the derailieur moves the chain up or down the sprockets/gears.

Adjust them incorrectly and the chain can either jump to many gears up or down not jump and also not in a smooth manner, another consequence of bad adjustment is the chain will jump bottom gear and scrape the inside of the frame (hence the paint damage) and also the reverse the chain can jump the top gear and jam in between the cassette and spokes.

Adjusting the H screw determines how the deraillieur moves the chain from the larger sprockets (gears) down ro the smallest one , adjust the screw out to far and it over rides the smallest and scrapes or jam's between the frame.

Adjusting the L screw determines how deraillieur moves the chain up the gears from the small sprocket . It takes patience and a clear head to work on the gears and one needs a bike work stand to suspend the bike to do the adjustments.

 

I have used the terms gears / sprockets , when describing a single gear it is conversely known better as a sprocket but when describing the adjustment which involves using the lever we say gears as we move up or down thru them.

Edited May 9, 20232 yr by Nealh

I just looked up your bike and it is a 21 speed with a 3 ring on the front. It’s also an ordinary hard tail MTB, so likely to have a 68mm bottom bracket. You need to measure it before buying the motor.

 

The cassette or freewheel and chain can be changed later. The hard part is fitting the motor.

 

You have to measure the frame width only. It won’t be 76mm.

 

It will be 68mm or 73mm you have to measure accurately. If it is 73mm, a 68mm kit will fit, but will need spacers. 100mm will not fit.

do you think its because i measured in inches. and my bikes the gt aggressor comp 2020

The OP is in way over their head as this stage, when it comes to bike components and terminology he or she has liitle/no idea what so ever with maintenance let alone a conversion.

I hate to be so blunt but at this stage it is the truth.

ok so? thats why im coming here to ask for help, if your going to be rude about it id rather you not even speak to be honest.

He isn’t trying to be rude. He is actually trying to help.

 

Bicycle maintenance is far more complicated than you think and does require mechanical skills and understanding. As well as owning and knowing how to use some special tools.

 

As Nealth suggested, watch plenty of YouTube videos to try and gain some understanding of basic bicycle maintenance.

 

Fitting a motor to your bicycle is not easy and even people who know what they are doing have trouble with some installations.

 

They don’t always bolt together easily and some times getting chain lines correctly aligned tasks even experienced people. If you have a 73mm bottom bracket as opposed to 68mm do you know how to fit spacers to adjust for the offset for example?

 

Also if you don’t know how to use a bottom bracket tool, crank tool, chain tool, freehub tool or cassette tool then you stand no chance of being able to fit a motor to your bike.

 

So best to learn the basics first.

We aren't rude ( well somtimes if we really put our minds to it ) but are truthful, we have a natural gut feeling to responding to users who are more then green behind the ears.

Most who attempt usually have a practical idea of how things work and how to carry the jobs out, specific tools are needed and often a bike stand is needed .

I would hate to see you waste several hundred £££'s and make a complete hash of your bike, better to take the bike to a pro to get it fitted full stop. Woosh bikes is one such pro in mind.

Edited May 9, 20232 yr by Nealh

ok so? thats why im coming here to ask for help, if your going to be rude about it id rather you not even speak to be honest.

 

It's an open democratic forum , you asked we have given some honest views/replies

You have already made one of the foremost ebikes experts nervous back in #3 .

He isn’t trying to be rude. He is actually trying to help.

 

Bicycle maintenance is far more complicated than you think and does require mechanical skills and understanding. As well as owning and knowing how to use some special tools.

 

As Nealth suggested, watch plenty of YouTube videos to try and gain some understanding of basic bicycle maintenance.

 

Fitting a motor to your bicycle is not easy and even people who know what they are doing have trouble with some installations.

 

They don’t always bolt together easily and some times getting chain lines correctly aligned tasks even experienced people. If you have a 73mm bottom bracket as opposed to 68mm do you know how to fit spacers to adjust for the offset for example?

 

Also if you don’t know how to use a bottom bracket tool, crank tool, chain tool, freehub tool or cassette tool then you stand no chance of being able to fit a motor to your bike.

 

So best to learn the basics first.

should i just go to halfords and ask them to fit it for me

Talk to Halfords first before buying anything. Halfords hourly rate is quite high.

 

Also create a new post on this forum to see if there are any bike mechanics local to you who would be interested in either fitting or better still supply and fit one for you.