swapping cassettes

[speedyebikenoob]

Hi guys, my cassette is looking pretty worn after being abused by my middrive over the miles. My bike came with an 8 speed 12-32t Shimano CS HG 200 cassette, and I'm looking at the Shimano HG 31 8 speed 11-34t cassette to replace it because I think slightly better first gear acceleration and a slightly higher top speed would be nice.

Is this possible? Would this be a simple swap? Or are these cassettes very different?

 

[JackFlorey]

Is this possible? Would this be a simple swap? Or are these cassettes very different?

Yes, swap is straightforward. Make sure your derailer can handle the range.

 

[MadRhino]

11t cog is very small for a motor driven chain. You will gain top speed at the cost or reliability, or durability. It is at the other side of the drive that you should change the gearing.

 

[speedyebikenoob]

11t cog is very small for a motor driven chain. You will gain top speed at the cost or reliability, or durability. It is at the other side of the drive that you should change the gearing.

Agreed, I will very very rarely be using the 11t cog though. I have no reason to ride 45+ mph most of the time. I'll generally cruise in 6th gear max.

 

[markz]

11t cog is very small for a motor driven chain. You will gain top speed at the cost or reliability, or durability. It is at the other side of the drive that you should change the gearing.

Agreed, I will very very rarely be using the 11t cog though. I have no reason to ride 45+ mph most of the time. I'll generally cruise in 6th gear max.

It is very hard to gear a bicycle to pedal 45+mph, 60T+ crank gear on a 10T rear gear. Ebikers dont need to pedal while going fast, ebikers dont need to pedal period.

 

[saskatchewanian]

A- Do you use your 12 tooth cog much?

B- Would you/do you ride at slowish speeds where the bike feels over-geared?

If you answered A, you are using 9th gear regularly, then I would suggest a bigger chainring. For the reasons brought up by others. You mention cruising in 6th so I don't think your top end gearing is really an issue.

If you answered B, and could use some lower gears by all means get a wider range cassette with a bigger big cog. There are 11-42t 8 speed cassettes available. I ended up going to the extreme and ordered a 11-50t 9 speed cassette from Box. With the big cog you will likely need a new derailleur or one of those hanger extender things.

If you answered A and B, combine the solutions.

*Stop reading here unless you want to read my anecdote about changing my gearing*

I ride both on trails and commute with my BBS02 powered mid drive fat tired ebike. The gearing when I got it was a 11-28t 7speed cassette with a 46t chainring. First gear was a great starting gear on pavement but too high for a lot of the slower work on the trails. The bike and I ran out of combined power pushing 5th gear when cruising on the flat. I'd sometimes be tempted to pop it in 6th but for the most part the top gears were useless.

Effectively my useful gearing was 15-28 with a pitiful 187% range. I was going to do a full upgrade with a wide range cassette to get some crawling gears and if it wasn't enough I'd also get a smaller chainring so the small cogs would be useful.

I got the 11-50 cassette mentioned above with a new derailleur and shifter. The smallest two cogs were still useless but I now had a decent low end for the trails, 7 useful gears with a 333% range. I didn't get the smaller chainring as the current gearing range works well enough, and my chainline is perfect in 6th gear which is where I mostly cruise when commuting.

Any additional gain I would get in gear range from a smaller chainring would be at the expense of durability and efficiency, hardly something worth throwing more money at when I already had that dinner plate of a rear cassette.

I think bigger cogs both front and back will last longer with less tension on the chain for the same amount of torque to the wheel, plus there is less friction loss.

 

[speedyebikenoob]

11t cog is very small for a motor driven chain. You will gain top speed at the cost or reliability, or durability. It is at the other side of the drive that you should change the gearing.

Agreed, I will very very rarely be using the 11t cog though. I have no reason to ride 45+ mph most of the time. I'll generally cruise in 6th gear max.

It is very hard to gear a bicycle to pedal 45+mph, 60T+ crank gear on a 10T rear gear. Ebikers dont need to pedal while going fast, ebikers dont need to pedal period.

Lmao, never tried pedaling with my motor at 45+ mph, don't think I ever will, so it does give me some flexibility with my gearing.

 

[speedyebikenoob]

A- Do you use your 12 tooth cog much?

B- Would you/do you ride at slowish speeds where the bike feels over-geared?

If you answered A, you are using 9th gear regularly, then I would suggest a bigger chainring. For the reasons brought up by others. You mention cruising in 6th so I don't think your top end gearing is really an issue.

If you answered B, and could use some lower gears by all means get a wider range cassette with a bigger big cog. There are 11-42t 8 speed cassettes available. I ended up going to the extreme and ordered a 11-50t 9 speed cassette from Box. With the big cog you will likely need a new derailleur or one of those hanger extender things.

If you answered A and B, combine the solutions.

*Stop reading here unless you want to read my anecdote about changing my gearing*

I ride both on trails and commute with my BBS02 powered mid drive fat tired ebike. The gearing when I got it was a 11-28t 7speed cassette with a 46t chainring. First gear was a great starting gear on pavement but too high for a lot of the slower work on the trails. The bike and I ran out of combined power pushing 5th gear when cruising on the flat. I'd sometimes be tempted to pop it in 6th but for the most part the top gears were useless.

Effectively my useful gearing was 15-28 with a pitiful 187% range. I was going to do a full upgrade with a wide range cassette to get some crawling gears and if it wasn't enough I'd also get a smaller chainring so the small cogs would be useful.

I got the 11-50 cassette mentioned above with a new derailleur and shifter. The smallest two cogs were still useless but I now had a decent low end for the trails, 7 useful gears with a 333% range. I didn't get the smaller chainring as the current gearing range works well enough, and my chainline is perfect in 6th gear which is where I mostly cruise when commuting.

Any additional gain I would get in gear range from a smaller chainring would be at the expense of durability and efficiency, hardly something worth throwing more money at when I already had that dinner plate of a rear cassette.

I think bigger cogs both front and back will last longer with less tension on the chain for the same amount of torque to the wheel, plus there is less friction loss.

Thankfully it's neither A or B for me. The 8th gear 11t sprocket or my "overdrive" gear is just so I can exceed 40 mph very occasionally for fun. My torque starts to fall off after 6000 rpm on my mini cyclone and at 6000 rpm in 8th I'm doing 46 mph, so it doesn't feel over geared. On the low end 6000 rpm takes me to 15 mph in first gear, which is probably taller than how your bbs02 is geared but I'm running nearly 4000w through this thing so it doesn't bog down on anything even uphill in lower gears XD

 

[saskatchewanian]

Ah so you aren't trying to fix an issue, it's just an opportunity to make it "more better".

A 11-34 will swap right in to replace your old cassette. You might have to adjust the B screw on the derailleur but it won't be much.

If you go bigger both front and back it might help with reducing wear. That's a lot of power going through a drivetrain designed for one human power.