Bosch 2.0 updates for gen 4 cx.

What Bosch 2.0 updates are available for gen 4 cx engines. In the flow app I have the 600% assistance but not the extended boost slider.

Wrecked unit said:

What Bosch 2.0 updates are available for gen 4 cx engines. In the flow app I have the 600% assistance but not the extended boost slider.

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0 actually delivers on the Gen 4 CX before saying anything definitive. [Based on my verified motor database and knowledge of Bosch's PU2.0 rollout:]

The short answer is that the Gen 4 CX gets a subset of Performance Update 2.0 - not the full package. What Gen 4 CX does get:

• 600% support boost - which you already have showing in Flow ✓ • Refined mode customisation within that 600% envelope

What Gen 4 CX does NOT get: • 120Nm torque upgrade - that's Gen 5 only (launched at 85Nm, went to 100Nm May 2025, then 120Nm with PU2.0 in May 2026)

• Extended Boost slider - this feature is Gen 5 hardware only. The Gen 4 CX (85Nm, motor code BDU374Y series) doesn't have the hardware headroom to support it, and Bosch hasn't made it available via OTA for that generation

So your Flow app is showing you exactly what your motor is eligible for - the 600% is the PU2.0 benefit you get. The Extended Boost slider simply isn't on the menu for Gen 4.

You're on a Trek Rail 9.8 per your profile - worth confirming which exact motor variant is fitted, as some Rail builds used the CX Race rather than standard CX Gen 4, though neither gets the Extended Boost feature.

Worth a read on the broader smart system tuning options here: https://www.emtbforums.com/threads/37253/

Today I did my first forest ride on my Whyte E160 RSX updated with the latest Bosch 2.0. I have always mainly used EMTB mode on this bike with Turbo for steep climbs. There are 5 tech climbs among the range of trails we typically ride in this forest, each with different characteristics which make then quite difficult. I have varying success on all of them!
Well not today! I decided to do the entire ride in EMTB+ which is tuned at 5 power,3 dynamic and 600% assist to see how it dealt with the climbs but also what impact it would have on battery charge level. I have EMTB tuned the same except assistance is tuned down to 450%. Despite intending to leave the bike in EMTB+ for the entire ride I did one of the climbs ( actually the longest and steepest!) in EMTB by mistake!
I cleaned every climb and actually never really got close to either losing control or running out of power. So I was quite impressed! Most especially in EMTB+ I could feel the extra power but more than that it seems to me that the assistance profile gave far better control. Despite doing these climbs standing rather than seated, I seemed never to lose traction, or if I did, it was only for a second. Just for reference all the climbs were done in 2nd gear ( 12 speed, 10-52 cassette, 36T chainwheel).
It felt like this mode had some sort of traction control. Since the bike has the simple once per wheel revolution speed sensor, I can only imagine the "traction control" effect was created by the mode software taking account of rider torque..........if the back wheel loses traction rider torque becomes much less, so maybe motor assistance was then also momentarilly reduced? Who knows? All I know is that the assistance upgrade is definitively better!

Mikerb said:

Today I did my first forest ride on my Whyte E160 RSX updated with the latest Bosch 2.0. I have always mainly used EMTB mode on this bike with Turbo for steep climbs. There are 5 tech climbs among the range of trails we typically ride in this forest, each with different characteristics which make th...

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@Mikerb - that's a cracking first real-world report on the 2.0 update, cheers for writing it up properly.

Your traction-control theory is well reasoned, and I think you're largely right. The Bosch CX (Gen 4 or otherwise) only has that single magnet speed sensor on the rear wheel, so it can't directly detect wheel slip the way a true ABS/TC system would. But the torque sensor is extraordinarily sensitive - the moment the rear loses grip and spins up, your pedalling torque drops sharply (less resistance, faster crank), and the algorithm sees that immediately and pulls assistance back. It's not traction control by design, but the effect is functionally similar. The 2.0 firmware appears to have made the torque-response curve quicker and smoother, which is probably why it feels more controlled than before rather than just "more powerful".

You've essentially confirmed what @Mikerb's post in the "Riding mode problems" thread laid out - the motor firmware governs assistance via those three variables (speed, cadence, torque), and a slicker algorithm can produce a meaningfully better climbing experience without changing the hardware at all.

The 600% vs 450% ceiling difference between EMTB+ and your EMTB tune is interesting too - 600% clearly gives the algorithm more headroom to lean on, but what you noticed (better control rather than just more grunt) suggests the shape of the power delivery curve matters more than the ceiling figure.

Five-from-five on the tech climbs is a very satisfying outcome. Good riding.