Jam2 6.7 - from 29’’ to 27,5”

[unclezz]

Hello!

I recently bought a 6.7 in size S for my wife.

She does not really like the feel of riding 29” tyres and the bike, even in size S, is pretty high.

I am thinking about replacing both tyres with 27.5” without touching the flip chip. Besides the ground clearance, do you see other issues or reason not to go for such conversion?

 

[steve_sordy]

Unless you can get the bike computer to alter the wheel size setting, the assistance will cut out sooner because the bike thinks you are going faster than you are (more wheel rotations per mile). Your LBS may have to do the wheel size setting changes for you (check first if they can, before buying your wheels).

There is a risk of more pedal strikes because the bike will be lower down. You could buy shorter cranks to counter this, in whole or part.

Bear in mind that you have changed your effective gearing by going for a smaller rear wheel. Your acceleration will be better, you can go up steeper hills, but your spin out speed will be down.

Have you considered just changing the rear wheel only?

 

[unclezz]

All good points!

Replacing only rear wheel means to turn the flip chip not to alter geometry. So it will not lower the bike height (which is actually my wife’s real goal)

I thought already about going to LBS for the firmware update. That should not be a big deal considering the bike is designed to run mullet.

Not worried with clearance to be honest because I will compensate with shorter cranks. The bottom bracket height is currently very high so it should not be affected that much.

 

[Satina]

We changed the flip chip on my Jam2 6.9 Very clever design as it also moves the magnet on the rear rotor which compensates the speed turning using the small wheel. So happy I got the 2022 as the 2023 model doesn't flip anymore.

 

[unclezz]

Ah Ah! So you're saying that you don't even need to ask the favor to a bosch dealer to update the wheel circumference!! This is a great news!!!

 

[Paulquattro]

The magnet position doesnt alter the rolling radius the wheel size does so you still need the wheel size recalibrated
One rotation is still one rotation no matter where the magnet is .

 

[unclezz]

The magnet position doesnt alter the rolling radius the wheel size does so you still need the wheel size recalibrated

yeah that indeed makes sense.
Actually this is one of th main rasons I don't like the Bosch closed-approach. It's pretty annoying that you need a dealer to change the wheelsize if you want the right readings for speed and distance.

 

[Paulquattro]

yeah that indeed makes sense.
Actually this is one of th main rasons I don't like the Bosch closed-approach. It's pretty annoying that you need a dealer to change the wheelsize if you want the right readings for speed and distance.

2022 kiox is different and of course there new smart system all wheel sizes are user adjustable
The older kiox allows adjustment but more of a tyre fine tune and speed calibration not a wheel size difference