Bosch shift detection - what does it do?

My Trek XM700 is equipped with the Bosch Performance Speed system, which features "shift detection". How does this work?

To reduce stress on the chain while shifting, I usually let up on my pedaling force before and during a shift. I'm wondering if this is unnecessary with a shift sensor.

Thanks to any and all who have some ideas about this.
 

Jeff Backes

Active Member
From all I can find on the internet, there may be some benefit with manual shifting, but I think the biggest win is with automatic systems like the Di2 and Nuvinci.

I don't feel and difference when I pedal.

jeff
 

pxpaulx

Well-Known Member
My Trek XM700 is equipped with the Bosch Performance Speed system, which features "shift detection". How does this work?

To reduce stress on the chain while shifting, I usually let up on my pedaling force before and during a shift. I'm wondering if this is unnecessary with a shift sensor.

Thanks to any and all who have some ideas about this.

You are correct, no need to let up the bike will sense the shift and lay off the power when the shift occurs. No harm in laying off though either.
 

Ravi Kempaiah

Well-Known Member
Shift sensing on the Bosch system had me intrigued me quite a bit.
On certain bikes like Kalkhoff, you have a physical device that is connected to the shifter cable and any movement of the shifter cable triggers the shift sensing.

On the Bosch system, it's more like a G-spot... no body knows whether they exist or not. Some think it does exist and works but I have ridden Bosch bikes (both Haibike Super race and Full Seven S Rx) for over 500 miles and did not feel the shift sensing mechanism. You can have clunky shifts under load.

From all my "internet" research and riding experience, all I could gather was ... the controller algorithm notices the change in crank rpm and the load and ensures smooth ramp up of the power. Since there is no device running along the shifter cable, once you have changed the gears, the motor doesn't put out the same torque it was operating at before the shift but rather rev up the motor smoothly.
And that's why Bosch system can feel under powered if you are shifting a lot because the system has to adjust itself for different gearing ratios.

I hope I made sense.
 

Chris Nolte

Well-Known Member
The Bosch Shift sensing actually detects the difference of the load on the chain via the torque sensor. This is not an easy thing to do, but they do it exceptionally well. This does not work with internally geared hubs though, but they do include a way for the motor to overcome this. In the most recent software the motor actually leaves small gaps in the assistance to allow for IGH shifts. It's not something you would notice but if you focus in on it you can feel the difference.

Keep in mind sensors made by Bosch can be found in most modern devices including the iPhone. No other system on the market senses as well as the Bosch in my opinion.
 

Don12

New Member
The Bosch Shift sensing actually detects the difference of the load on the chain via the torque sensor. This is not an easy thing to do, but they do it exceptionally well. This does not work with internally geared hubs though, but they do include a way for the motor to overcome this. In the most recent software the motor actually leaves small gaps in the assistance to allow for IGH shifts. It's not something you would notice but if you focus in on it you can feel the difference.

Keep in mind sensors made by Bosch can be found in most modern devices including the iPhone. No other system on the market senses as well as the Bosch in my opinion.
Hello does shifting sensing have to be enabled by the end user or is it an automatically enabled feature? Thanks for your help
 

TrevorB

Active Member
I've never noticed any shift sensing on Bosch CX drive, no real difference than Shimano Steps. For both drives I easy off or stop pedalling for shift especially when under high loads, both motor runs on for a second and complete shift..
 

Chris Nolte

Well-Known Member
I've never noticed any shift sensing on Bosch CX drive, no real difference than Shimano Steps. For both drives I easy off or stop pedalling for shift especially when under high loads, both motor runs on for a second and complete shift..
You can notice it if while pedaling normally you push the shifter and not actually shift. If you do that while paying attention to the power indicator on the right side of the display you’ll notice the power back off. This happens since the motor senses the difference in the amount of tension applied to the chain in this example.
 

tallpaul

Active Member
I have noticed the shift sensing on my Bosch Performance drive. it happens subtly and quickly.
I assume that backing off the power when shifting puts less strain on all drivetrain components, especially the chain.

Speaking of chains, is there a clear "best" chain that anyone knows of for our bikes?
I replaced the original Shimano at 1200 miles with an ebike specific chain by KMC but after another1200 or so miles can tell it is getting noisier.
To keep it quiet I have to lube it every ride of 25 miles or so, and that is mostly over asphalt and cement bikeways.
And the only lube I found that quieted it down, even for just one ride, was MucOff C3 Ceramic lube.
 

Ravi Kempaiah

Well-Known Member
With over 5K+ miles on Bosch powered bikes, I can say the Shift detection works quite well.
The pre-2016 version may have been slightly different but the ones coming out the last few years with smaller chainring, it sure does.
The motor detects sudden change in the torque levels because of the gearing and it smoothly ramps up the power after a very quick stop in power transmission. It's a nice feeling when your shifts are smooth.

Strangely, I tested the active line plus motor (the bigger chainring) and the shifts were still clunky. It was a Trek Verve+ and I went upto the Bosch rep and asked him about this. He didn't have any clue either.
 

Sweetwater

Active Member
Having recently upgraded to a 1 Gig Nyon, I can see the shift zones on the display very clearly.
However, my buddy has a new Yamaha on his Haibike and I've been very impressed with it.
Seems that the competition has improved products incrementally since my 2016 system.
Not yet time to trade up but that will be a consideration in another year or two.