Internal Hub Gears for Ebikes
 

Are IHG good for electric bikes? I hear I need to have a gear sensor if want to use ihg with mid motor. What is the reason for it ?

Nuvinci N380 bills itself for e-bike use. The Harmony interface is supposed to change ratios as needed automatically to keep whatever cadence you desire. If you are light weight with no cargo they are rated up to 500 watts continuous duty with a Bosch system. Less so depending on total weight & power combinations. 250 watts for a 400 pound bike/carge/rider sounds right.

The thing about an IGH is the inability to shift under power. You can't, it either won't shift or it will self destruct in short order. (except supposedly Rohloff) For the Nuvinci, it doesn't matter, there are no gears. Infinity also equals zero.

I used a NuVinci N380 and a bafang mid drive on my Kansas to Utah tour. It was great. I didn't use a throttle on the bafang. Instead I relied on its rotation sensor. The NuVinci allowed precise trim of speed and power draw.

My current build does not have on, simply because I don't have a spare NuVinci lying about. It will eventually get one. This is a good article on the topic.

Bosch mid drive motors have versions that are optimised for IGH use (the maximum torque is different), for Shimano Nexus/Alfine, Rohloff, and NuVinci hubs. You can even go full automatic shifting if you want with a Di2 system (Shimano).

(I work for a Bosch service shop and I own a Bosch-equipped e-bike, but mine has a derailleur)

The list of which drive units with what drive system: https://www.bosch-ebike.com/en/products/drive-unit/

Electronic shifting and/or IGH specific infor: https://www.bosch-ebike.com/en/products/eshift/

You can buy a bike with a Bosch MidDrive , and an Electronically synchronized & shifted Rohloff ..

As I understand it, the interface is such that the motor pauses on the power out put just long enough to change gears in the hub..

Good article on IGH for mid-drives https://www.electricbike.com/mid-drive-kit-igh/
I use a Nexus 8 with a BBS01, it's a good idea to have some way to stop the motor before shifting and there are 4 solutions for the bafang - gear sensor, big green button, brake lever motor inhibitors, and pause pedalling - I prefer the gear sensor to the big green button as its more intuitive and one less thing to have to think about when shifting.

Retrofit Rohloff to BOSCH
 

If I were to fit a Rohloff to a BOSCH Active line plus would I need to upgrade the firmware of the BOSCH?

Rohloff has an electric shift hardware upgrade for the , cable external shift box

One of my mates at the local bike shop went to a multi day seminar
conducted by Trek bikes in another city in the state,
on Bosch motors service and function ..

But I have not read the manual , nor have a convenient link for you,

, perhaps you need to talk to the dealers staff at a full service bike shop
selling them to get the in depth answer..







....

I always see this as an issue, but all you have to do is pause pedaling for a sec to shift. It takes a tiny bit of practice, but it is a really easy adjustment to make.

Indeed. I only posted it as an FYI sort of thing. Some people don't know, & the hub gets chunky, shifts terrible, then self destructs. Then they do the natural human thing & blame the hub or the maker as defective garbage. When the reality is it just isn't so. TBH I'd like to see a lot more IGH options on OEM bikes. They really are fantastic for so many uses.

Yeah, it makes so much more sense for an e-bike.