Freewheels, Cassettes & Chains

[nikon201]

Hello

I've been riding my Synergie Mistral for a couple of weeks and have found the gearing range unsatisfactory. I've been reading some of the recent threads about gearing with interest, but I have some questions. This is probably due to my last experience modifying bikes was 25 years ago

The Mistral has a Shimano MF-TZ06 28-14 6-speed freewheel, and I've been looking for something with a wider range. It would appear that there is more of a choice with cassettes than freewheels, what would be involved in changing to a cassette? Is is possible?

The chain is a KMC (Z series?) 124 links, and I'm guessing I will need a longer chain plus a new derailleur. I'm struggling to find any chains that are this long to purchase, would I be needing to custom build my own chain to do this?

I'd appreciate any help before I start getting grease on my hands!

Thanks
Jon

 

[flecc]

You cannot change to a cassette with a rear motor Jon, you only have a freewheel thread on the motor. Assuming it has a standard freewheel thread and not a BMX one, and that's fairly certain to be ok, you have this from Shimano:

Cadet megarange freewheel. This has 5 sprockets from 13 to 24 teeth and a large 34 tooth one as an extra low gear. I use these 6 speed ones on my two rear motor bikes.

That's it where wider range six speeds are concerned, but if you widen the frame a fraction and use a 7 speed, you have this option:

Shimano HG50 freewheel 11 to 24 plus the 34 tooth low.

To use either of these you will need a new megarange capable rear mechanism like this Acera one, and to use the 7 speed, you'll need a new control as well of course.
.

 

[nikon201]

Thanks Flecc that's very helpful, would I also need a new chain?

 

[flecc]

Yes, it wouldn't be worth trying to use the existing one, even if only slightly worn, as it would just lead to a rougher gearchange and rough sounding running. Luckily the prices of all this kit are very reasonable as you've seen. You may need to buy two chains though, since e-bikes have longer chain runs due to the battery, one chain often being not quite long enough.

If doing the job yourself, you'll need a freewheel removal tool and a chain whip for removing the freewheel, plus a chainlink tool.
.

 

[rooel]

Might I just add to flecc's advice that if you fit the Shimano Megarange you can still use the existing derailleur. It needs some fine adjustment but it just manages to lift the chain up on to that 34 tooth sprocket.

 

[nikon201]

Thanks rooel I've been wondering about that, although it does look extremely close!

 

[flecc]

Might I just add to flecc's advice that if you fit the Shimano Megarange you can still use the existing derailleur. It needs some fine adjustment but it just manages to lift the chain up on to that 34 tooth sprocket.

That's good to know on the Mistral Rooel, most of these e-bike mechs don't cover megarange well. Mind you, the megarange suitable ones can be quite cheap, as little as £11 sometimes, and the lift onto the big sprocket is lightning fast with the right mechanism.
.