Changing from 44 to 48 t

[Russ34]

Hi , I’m presently using a 44t front sprocket and a 7 speed rear with an 11t as my smallest cog at the back , as I’ve posted on here my bike is wearing out the smallest cog quickly, I’m thinking of changing the front to a 48 and smallest cog to a 12 , I use my bike to commute 15 miles in hilly Devon ! Can anyone see a problem with this please ?

 

[Benjahmin]

So long as the deraileur has enough travel to accomodate there shouldn't be a problem, may possibly need a chain with a couple of extra links.
I run a 48/38/28/front with 12 small rear cog, downhill I spin out at around 34mph.

 

[StuartsProjects]

as I’ve posted on here my bike is wearing out the smallest cog quickly

If the (small) rear cogs on the cassette\ freewheel are wearing 'quickly' then there is a problem to be solved.

Which I cannot see why that would be resolved by changing the size of the front chainwheel.

 

[Russ34]

If the (small) rear cogs on the cassette\ freewheel are wearing 'quickly' then there is a problem to be solved.

Which I cannot see why that would be resolved by changing the size of the front chainwheel.

It would possibly solve it because I was going to change the 11 for a 12 , to reduce the wear

 

[StuartsProjects]

It would possibly solve it because I was going to change the 11 for a 12 , to reduce the wear

I have used a 11 on the rear for years, I have not had any specific 'wear' problems that I am aware off.

 

[Russ34]

I have used a 11 on the rear for years, I have not had any specific 'wear' problems that I am aware off.

Ok bud , maybe just my set up then

 

[soundwave]

i have got 1000s of miles out of my chains cassettes and sprockets and the key to this is keeping everything as clan as possible otherwise it just turns in to a grinding paste.

other issue could be the chain line as i need a spacer on my motor to push the sprocket out a extra 2.5mm.

 

[Russ34]

i have got 1000s of miles out of my chains cassettes and sprockets and the key to this is keeping everything as clan as possible otherwise it just turns in to a grinding paste.

other issue could be the chain line as i need a spacer on my motor to push the sprocket out a extra 2.5mm.

Thanks for your reply

 

[georgehenry]

Crank drives wear your transmission.

If you spend a lot of time in top gear you will wear it out quickly as cogs with less teeth are more susceptible to wear.

Using a 12 tooth cog instead of an 11 will help. Raising your gearing to the point where a 13 tooth or 14 tooth gear works at the speed you want to travel at will be even better. The more teeth the more resistance to wear.

However you still need a low enough gear to get you up the steepest hill you need to climb.

Raising your gearing is a simple solution if you spend a lot of time in your top gear and wear it out quicker than the rest of the cassette and it does work. I did the same when commuting to work and back on my hard tail Haibike.

Mine was a 9 gear transmission and I used a 12/36 rear cassette.

 

[Russ34]

Crank drives wear your transmission.

If you spend a lot of time in top gear you will wear it out quickly as cogs with less teeth are more susceptible to wear.

Using a 12 tooth cog instead of an 11 will help. Raising your gearing to the point where a 13 tooth or 14 tooth gear works at the speed you want to travel at will be even better. The more teeth the more resistance to wear.

However you still need a low enough gear to get you up the steepest hill you need to climb.

Raising your gearing is a simple solution if you spend a lot of time in your top gear and wear it out quicker than the rest of the cassette and it does work. I did the same when commuting to work and back on my hard tail Haibike.

Mine was a 9 gear transmission and I used a 12/36 rear cassette.

Thanks for your reply , what size did you have on the front ?

 

[georgehenry]

I used a narrow wide 42 tooth chain ring.

I bought my hard tail Yamaha crank drive Haibike to commute to work using off road tracks for nearly all the journey.

As a shift worker I traveled mostly in the early to mid afternoon. I then charged my battery while I worked and then rode home mostly after midnight.

I rode home on the road as I wanted to get home as quickly as possible. The route to work was usually around 14 miles off road, and the route home was 10 miles on the road. My bike could assist above the cut off limit and I could average around 20mph for my 10 mile journey home on the road.

However I still needed to be able to climb the steepest part of my off road route to work and that meant a 42 tooth chain ring was the largest I could get away with and still be able to climb my steepest hill in lowest assist and bottom gear (36 tooth sprocket) This meant that the fastest speed I could pedal at was around 25mph.

Even riding home I mostly used my lowest assist setting and only the middle higher assist level to climb hills quicker or maintain speed over the crests of longer hills.

As I used my lowest assist level riding on level slightly up, slightly down sections, I would mostly be traveling at 20 to 23mph.

I turned the assist off for steeper downhill sections to conserve the battery. The fastest speed I went on the steepest downhill road section coming home was 36mph with the assist off.

I bought my bike in the Spring of 2015 and retired from work in October 2021.

Since retiring I have lowered the gearing, again simply by changing the 42 tooth narrow wide chain ring for a 38 tooth one, as the bike gets used now for exercise leisure rides and some shopping.

The mileage of my bike now stands at 16,426 miles. I am still using the original battery. It and the bike will be 8 years old in March 2023.

 

[Bikes4two]

Crank drives wear your transmission.

Well, yes and no (just to put this into perspective for new to e-bike readers.).

I came to my ebike (TSDZ2 conversion of a Dawes Galaxy) due to reducing cycling power (an age thing ) and thus I used the motor to get me back to my 'pre-aged' level, and as such I use ECO mode almost exclusively and I do not get anymore transmission wear (chain, sprockets or chain rings) than I did when riding unassisted.

However, I'm sure that if I were to ride TURBO mode all of the time, then transmission wear would increase (the same as it would if Sir Chris Hoy rode my bike ).

If you spend a lot of time in top gear you will wear it out quickly as cogs with less teeth are more susceptible to wear.

Using a 12 tooth cog instead of an 11 will help. Raising your gearing to the point where a 13 tooth or 14 tooth gear works at the speed you want to travel at will be even better. The more teeth the more resistance to wear.

However you still need a low enough gear to get you up the steepest hill you need to climb.

Raising your gearing is a simple solution if you spend a lot of time in your top gear and wear it out quicker than the rest of the cassette and it does work. I did the same when commuting to work and back on my hard tail Haibike.

Mine was a 9 gear transmission and I used a 12/36 rear cassette.

100% agree - I have observed that some ebike riders who have maybe not a great deal of unassisted cycling experience, don't use the gears very much, so typically when on climbing a hill, I will drop gear to cope, some ebike riders just raise the motor power instead, a technique that will lead to greater transmission wear.

As other have said, I've cycled 10's of thousands of miles and never had an 11 or 12 tooth spocket wear out - the mid range ones, yes, but not the smallest one.

Excessive wear on the 11T sprocket could be down to the things already mentioned, or rubbish manufacturing, or riding style (as per what I mentioned above about gears etc)?

 

[georgehenry]

That is the trouble when answering any question, there are usually quite a few variables that effect the answer and can mean that two answers from separate people to the same question can give different answers and both be correct!

When I first started using my Haibike Yamaha to commute to work I was quite shocked how quickly I could wear out the top gear on my rear cassette. It came with a cassette with an 11 tooth top gear.

I learnt what factors were important for my transmission and the way I used my bike.

One important factor was that I rode to work using a 14 mile almost completely off road route. This got the transmission dirty with no chance to wash the bike before my ride home. The best I could do was add some chain oil. So when riding home on the road using mostly my higher gears a dirty transmission would have been a factor in the wear rate.

In my opinion The Yamaha motor is a peach, but it does not have interrupt technology to momentarily reduce the power from the motor when you change gear. So if you ride a bike with that motor and change gear unsympathetically you will greatly increase the wear levels.

So in my initial learning curve I had to develop my riding technique to change gear as gently as possible, a style that becomes intuitive over time, where you almost ghost pedal during the change. I also learnt to use predominantly my lowest power assist in top gear.

Ridden sympathetically my cheap replacement Shimano steel 12/36 9 speed cassettes could achieve my targeted 20mph average for my 10 mile ride home taking 30 minutes and despite the transmission being dirty from the cross country ride to work I could get up to a 2000 mile life out of the rear cassette.

Commuting daily, in my case a 24 mile round trip is different from leisure rides. You don't get the time or have the energy to clean your transmission as much as would be ideal.

You are more likely to spend extended periods of time in your highest gear.

If this is the case then using higher gearing so that you can travel at that higher speed in a cog with more teeth is a simple solution that will extend the life of your cassette even if you cannot keep it as clean as would be ideal.

Now I am retired and do not have that need to complete a journey at a high average speed (for a bike) my current cassette is at 2,107 miles with no sign of wearing out as I am now using all my gears in a more balanced way than when I was riding home from work tired late at night after the end of my shift.

 

[Russ34]

Thanks for your interesting replies , my main question also could I harm the motor by increasing the demand by putting a 48 instead of a 44 ?

 

[Bikes4two]

Thanks for your interesting replies , my main question also could I harm the motor by increasing the demand by putting a 48 instead of a 44 ?

At a guess and definitely not scientific, I'd say 'no harm' given that some folks (you can read about them on the endless sphere forum) drive these motors at 750w over mountain trails in goodness knows what ambient temperatures and rider weights (but they do get problems mind you - over heating, axle breakages) but usage like that is far removed from having a 48t chain ring, so go for it.

 

[Russ34]

At a guess and definitely not scientific, I'd say 'no harm' given that some folks (you can read about them on the endless sphere forum) drive these motors at 750w over mountain trails in goodness knows what ambient temperatures and rider weights (but they do get problems mind you - over heating, axle breakages) but usage like that is far removed from having a 48t chain ring, so go for it.

Thanks for your reply