st unlock and smaller chain ring

[urastus]

Hello. I have a merida e140 LTD. It has a 34 tooth chain ring and 11-51 cluster. I'd like to fit a 30 tooth chain ring. Are you able to make this change in the firmware with st unlock? I have seen screenshots of the chain ring entry in st unlock, but don't know if it can accept non standard chain ring sizes.

 

[Nickolp1974]

Isn't that setting in software for Di2??

 

[Zimmerframe]

There was talk of removing that field in stunlocker as it didn't work correctly.

There is no need to change the size number though, it won't affect anything other than possibly walk mode speed if you have a di2 bike.

 

[Stuart569]

Isn't that setting in software for Di2??

I'm 99% sure that editing gear configuration isn't required unless you use Di2 shifting. Even then i'm not sure what it does.

 

[Stuart569]

There was talk of removing that field in stunlocker as it didn't work correctly.

There is no need to change the size number though, it won't affect anything other than possibly walk mode speed if you have a di2 bike.

Surely it would take the speed for that from the wheel pickup and target? Anyway, agreed, gear config is not required!

 

[Zimmerframe]

Surely it would take the speed for that from the wheel pickup and target? Anyway, agreed, gear config is not required!

I don't think anyone could work out for sure if the di2 bikes worked it out based on gear sizes or wheel rotation speed, as the power applied is different depending on the gear you're in - the speeds are so low it's probably difficult to get a reliable reading.

 

[iXi]

Don't change the chain ring size in St unlocker or it'll brick your controller. It's an easy fix to revert it if you do but It does nothing changing it in the app anyway

 

[urastus]

Thank you all. I thought there might be some wizardry at play re torque applied. It's nice to know that it isn't that complex

 

[urastus]

Just been reading through the st unlock manual. It's strange; he has the entry for the chain ring and smallest cluster gear. You can choose mechanical or Di2. It could just be for information? I imagine the Di2 would communicate with the system once the system knows it's there? For example, the system can tell you what gear you're in. Why chain ring size and smallest gear size - maybe something to do with maximum speed / cadence / assistance. It would be interesting to see what the black box feature shows - does it have this information (chain ring / smallest rear gear). Incidentally, I found that 30 tooth chain ring and 10-45 cluster, in the lowest gear it is the same as 34 tooth chain ring and 10-51 cluster in the lowest gear (both 18.8 gear inches on my bike).

 

[Zimmerframe]

Just been reading through the st unlock manual. It's strange; he has the entry for the chain ring and smallest cluster gear. You can choose mechanical or Di2. It could just be for information? I imagine the Di2 would communicate with the system once the system knows it's there? For example, the system can tell you what gear you're in. Why chain ring size and smallest gear size - maybe something to do with maximum speed / cadence / assistance. It would be interesting to see what the black box feature shows - does it have this information (chain ring / smallest rear gear). Incidentally, I found that 30 tooth chain ring and 10-45 cluster, in the lowest gear it is the same as 34 tooth chain ring and 10-51 cluster in the lowest gear (both 18.8 gear inches on my bike).

If you have a none di2 bike and add di2 to the bike (using the e8000/e7000 display and motor connections), you used to have to get the dealer to re-configure the system to di2. Stunlocker lets you do that yourself. You can change it to Di2 and anytime and it will auto detect that di2 isn't there and revert to normal (so not sure why they don't just configure them all like that from the factory).

If you have Di2 it shows the gear on the screen and so on and walk mode works better because it know which gear you're in, so there's no chance of someone cheating and holding down the walk mode button and using it as a 25kph no pedal moped.

Black box is just the data configuration for the unit. Possibly it also keeps some historical logs. I started trying to decode it one day and started a thread .. It was suggested I should be less of a sad git and go for a ride instead .. I did .. it was sound advice

If a motor's been de-restricted I'm pretty sure they can work it out if they really want to, just compare charge cycles to distance for instance gives you a good starting point.

Don't get tempted to change the power settings, ie 500w to 600w - this can burn the motor out.

 

[urastus]

Thanks zimmerframe (awesome name). All I want to do is have all, or at least most, of my gears "usable". It seems pointless having 12 gears when you predominantly use 8. I think, especially with ebikes, they could have come up with a better cluster range, say 45-14 or 51-14. I wonder if anyone gets to use the 10 tooth gear with a bike that is assisted to 25km/h or even 32km/h?

 

[Zimmerframe]

Everyone's different on what terrain they ride, what speeds they ride, what cadence they pedal - so there is no perfect or ideal.

For me, I found with the shimano and the standard 34t it was pretty good and I used most of the spread of gears.

When I switched to a Kenevo with a standard 32t I found I was mainly using just the higher gears and hardly ever using the big rings. So similar to yourself in my concerns, but the other way round. So switched to a 36t as I was worried I'd wear out all he small rings far quicker than I should do. The only times I've regretted that is on flat battery climbs

You don't need to be on much of a descent before you overcome "bike drag" and you find yourself pedalling like a manic to help gravity and go as fast as possible.

With the motor assistance though, 12 gears is probably overkill on an e-bike. Quite a few people use 8 and find that fine. 10 is probably the ideal compromise for most situations and has the advantage that it's easier to setup requiring less precision and is cheaper too .

 

[urastus]

Ok. I really didn't think it was possible to pedal in 12th and still be under 25km or 32km / h. I'd probably get to 10th, maximum, I haven't yet. It was arrogant of me to assume others would have the same problem . Indeed, it could also be my bike setup as well.

 

[Zimmerframe]

It probably isn't On the flat, you wouldn't have the power to push through past the limiter - unless you were hulk.

I found with the Shimano you could (depending on tyres) push upto about 36kph on the smooth and flat. Less if it's not smooth. I'm sure more powerful riders could go faster and for longer.

If you're descending and pedalling, I find the 36t gets me to 50kph then I start feeling I'm spinning a bit quickly. Faster than that and I'm normally more focused on staying on than pedalling

You might just find with time that you end up riding faster and the gears start feeling like you have a better spread. That's what I found anyway.

 

[urastus]

Yeah, I generally hit the limit of assistance then give up pedalling not long after that . On my acoustics I'm often pedalling up to 40km/h (mtb's and with the assistance of gravity). Beyond 40, I'm usually in the wing position flying down a hill.