Changing a cassette on an e-bike/ granny gear!

[donkeykong]

Hello,

I have a Kudos Stealth and have been fairly impressed with it so far. However, I have some very steep hils on my commute and I find that even in my lowest gear that my cadence is really low which puts a bit of strain on the knees!

I was thinking that I could change the cassette so that I have a "granny gear"... would this work and any recommendations?

 

[anotherkiwi]

What is your lowest gear? Sunrace make a wide range 11-40 otherwise 11-34 is pretty common.

 

[donkeykong]

What is your lowest gear? Sunrace make a wide range 11-40 otherwise 11-34 is pretty common.

After counting and getting my hands dirty I think its 13-34... All I got from the specs online is Shimano Acera 8-speed derailleur, 46 tooth chainring.

What if I change to a lower tooth chainring?

 

[chris_n]

Won't going even slower just mean the motor becomes less efficient necessitating another lower gear which will make the motor less efficient ad infinitum?

 

[Gubbins]

I think he means his lowest gear is still too high for efficient pedalling. Have had the same trouble myself and managed to fit a smaller chain ring and a cassette with a bigger low gear

 

[chris_n]

I think he means his lowest gear is still too high for efficient pedalling. Have had the same trouble myself and managed to fit a smaller chain ring and a cassette with a bigger low gear

I understand that and have done the same with my Haibike for use in the mountains but I thought with a hub motor if you are going too slowly then the motor is less efficient and generates more heat.

 

[Gubbins]

I understand that and have done the same with my Haibike for use in the mountains but I thought with a hub motor if you are going too slowly then the motor is less efficient and generates more heat.

I found that by lowering the gearing a bit I was able to make a slightly better spead easier just by being able to pedal faster.

 

[chris_n]

Ok with you as long as the actual speed remains the same.

 

[Deleted member 4366]

The idea is good but before anything, you need to establish whether you have cassette or freewheel gears. Cassette is on a spline held on by a retaining collar on top of top gear. freewheel gears screw on to a big thread on the hub and don't have the retaining collar. Look on Google for pictures to see the differences.

 

[donkeykong]

Helpful replies, cheers.

What if I just reduce the size (less teeth) of the chainring? I quite like high cadence - keeps the legs in good shape for a weekend ride on my (non-E) road bike!

 

[anotherkiwi]

You could go for a 44, I have a 42 as replacement for a 46 and it is just that little bit too much. Your cassette will be an Acera HG41 11-34 which is already a pretty low gear.

This might help:

http://www.bikecalc.com/gear_inches

 

[Deleted member 4366]

You could go for a 44, I have a 42 as replacement for a 46 and it is just that little bit too much. Your cassette will be an Acera HG41 11-34 which is already a pretty low gear.

This might help:

http://www.bikecalc.com/gear_inches

He already said it's 13/34. Smells of a freewheel to me, especially as I know for a fact that Kudos fitted 13/34 freewheels to the Tornado.

 

[Deere John]

I like granny gears have lots of steep hills. On my eMTB I have 48T biggest cog. You just have to set the assist level to a littlle lower (3 of 5 for example) and then just pedal easy up any hill.

 

[donkeykong]

I've ordered a 42t replacement chainring. Would I need to change anything else e.g. chainlength, derailleur?

 

[Deere John]

well, maybe shorten the chain (4 links) just a little to get the same derailleur swing

 

[Nealh]

For correct chain length place said chain on largest front ring and largest rear gear (not through rear derailleur) where the chain meets add one or two links and mark it then shorten to this. Rethread through derailleur and join with a quick link.

 

[donkeykong]

Have swapped to a 42t chainring and the bike ain't happy. I haven't removed any links yet but I'm wondering if there are other issues. The chain isn't sitting properly on the chainring - it's as if the width between teeth is different - or is this just because there is now slack in the chain? If I try cycling, some of the links will coil up on each other then the chain will come off!!!

 

[wheeliepete]

Worn chain? How do the teeth look on your old chainring?

 

[Deere John]

Is it a normal chain ring or a narrow wide? (NW has different widths on every second tooth)

Sent from my eBike through Tapatalk

 

[donkeykong]

The chain is looking pretty rusty... although I've only had it 5 months. The new chainring I have bought is a system EX 42T which apparently fits "any 130 PCD crank". But the spec also say "for 1/2 x 1/8 Chains"... is this where I've gone wrong?!?!