Proper Middrive Shifting technique?

Tommm said:

Depending on the rpm of your drivetrain, the motor and chain might have enough inertia to complete a shift while off the throttle.

When shifting under power, just hold the throttle to a lower rpm than whatever speed you are going, that way the whole system is freewheeling and not under stress.

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Chalo said:

Shifting under power in either direction is abusive to the chain and sprockets, and should be avoided whenever possible. The noise is worse when upshifting, but it's just as damaging when downshifting-- possibly even bending sprockets or dislodging chain pins.

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speedyebikenoob said:

Chalo said:

Shifting under power in either direction is abusive to the chain and sprockets, and should be avoided whenever possible.

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If I hold the throttle in a steady position though is it really shifting under power?

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Chalo said:

speedyebikenoob said:

Chalo said:

Shifting under power in either direction is abusive to the chain and sprockets, and should be avoided whenever possible.

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If I hold the throttle in a steady position though is it really shifting under power?

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Yes. Modern gears are designed to be able to complete a shift under load, but it still puts sometimes damaging stresses on them. MTB riders often depend on their bikes being able to downshift when they're pedaling hard... and sometimes they break their chains or bend sprockets. That's how it goes.

A given steady throttle position may or may not cause a load to be on the chain, depending on how fast you're going, what type of throttle and what position it's in. But if letting up on the throttle would cause you to slow down, then yes, you are shifting under load. The chain and sprockets don't care how fast you're moving or whether you are accelerating or decelerating-- it only matters whether they are running with tension on the chain.

They're your toys. Break them if you like.

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dustNbone said:

Basically just make sure there's no tension on the driveline during the shift. You want things to be turning, but not under stress.

So for a downshift, you basically only need to slow it down enough to take the tension off your freewheel(s), because after the shift there will be even more "slack" and you'll have to speed it up after the shift to load things back up again.

Try to be gentle about hitting the throttle again after the shift, you just want to "bump" into the freewheel and then once all the slack is gone you can ham it.

Upshifting you want to give it lots of "slack" by slowing it down enough to remain unloaded after the shift. If you don't slow it down enough, once the gear shifts and the controller detects the lower speed it will apply full(ish) power to restore speed to match throttle position.

This will put lots of strain on everything, freewheels, internal gears, chain, cassette gears, etc. So you really want it turning just fast enough to complete the shift, then as with the downshift gently bump things back into tension and off you go.

It takes practice, and modern chains and gears will take an amazing amount of abuse without slipping or even making horrible noises, but it's going to wear things out.

I don't recommend a shift sensor, it will never be able to do as good of a job as a human with some practice and an understanding of what's going on mechanically.

I have found the best shifter configuration for my BBS02 bike to be a grip shifter on the left bar with thumb throttle on the right, with this I can coordinate things very well and shifting becomes second nature. I can do it very quickly without mashing up any parts.

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speedyebikenoob said:

dustNbone said:

Basically just make sure there's no tension on the driveline during the shift. You want things to be turning, but not under stress.

So for a downshift, you basically only need to slow it down enough to take the tension off your freewheel(s), because after the shift there will be even more "slack" and you'll have to speed it up after the shift to load things back up again.

Try to be gentle about hitting the throttle again after the shift, you just want to "bump" into the freewheel and then once all the slack is gone you can ham it.

Upshifting you want to give it lots of "slack" by slowing it down enough to remain unloaded after the shift. If you don't slow it down enough, once the gear shifts and the controller detects the lower speed it will apply full(ish) power to restore speed to match throttle position.

This will put lots of strain on everything, freewheels, internal gears, chain, cassette gears, etc. So you really want it turning just fast enough to complete the shift, then as with the downshift gently bump things back into tension and off you go.

It takes practice, and modern chains and gears will take an amazing amount of abuse without slipping or even making horrible noises, but it's going to wear things out.

I don't recommend a shift sensor, it will never be able to do as good of a job as a human with some practice and an understanding of what's going on mechanically.

I have found the best shifter configuration for my BBS02 bike to be a grip shifter on the left bar with thumb throttle on the right, with this I can coordinate things very well and shifting becomes second nature. I can do it very quickly without mashing up any parts.

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Okay, I basically do this so I guess it's okay then. That's why I don't want a shift sensor, I don't want power to cut off completely when I'm trying to downshift and I'm about to go uphill, I like having control over it. I'm considering adding a shift sensor though and having a switch for turning it on and off for when other people want to ride my bike.

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