Do Bosch motors add resistance at the class 1/3 support limit?

[AvalancheRun]

Btw, I don't mean to cast doubt on the comments written here. I run tire pressure on the low end, and always carry ~20 lbs extra weight.

 

[wildtrak]

Did some more tests. I can get the bike from 0-20 mph unpowered *relatively* easily and sustain 20. 21-22 is still impossible.

When trying to get past 20/21 I peak around 600 watts. Probably not a huge number compared to real cyclists, but it still seems weird that my cut off is exactly at the class 1 limit.

That is funny though.
Sounds like your cut off on a class 3 with a Bosch would then be 28 Mph if you ride it with no assistance.
What is your limit coasting down a hill? My bikes all cut off at 55Mph on my "Home Hill", with or without motor.

The difference in the workout is incredible!

Exactly, I do also get way more workout on my bikes with the Bosch, because it is just way more fun.

 

[Jeremy McCreary]

Btw, I don't mean to cast doubt on the comments written here. I run tire pressure on the low end, and always carry ~20 lbs extra weight.

Factors to be considered for sure. But at the speeds involved, total (bike+rider+cargo) weight and tire pressure probably have little to do with the issue raised in your original post.

On smooth, hard, flat pavement with no headwind, the lion's share of total (air+slope+rolling) resistance at 20 mph (9 m/s) is air resistance — which depends on total weight only loosely through total frontal area. The only common road resistances directly dependent on weight are slope and rolling resistance. And at 20 mph, their combined contribution to total resistance on flat road is 10-15% at best.
 
The graphs of relative resistance vs. ground speed posted here tell the story. The plotted speeds are in m/s. To a very good approximation, 20 mph = 9 m/s, and 22 mph = 10 m/s. Data used comes from Wilson & Schmidt, 2020, Bicycling Science, 4th ed.

 

[Stefan Mikes]

Did some more tests. I can get the bike from 0-20 mph unpowered *relatively* easily and sustain 20. 21-22 is still impossible.

When trying to get past 20/21 I peak around 600 watts. Probably not a huge number compared to real cyclists, but it still seems weird that my cut off is exactly at the class 1 limit. Granted I need to hop back on my acoustic bike which I've neglected for months. The difference in the workout is incredible!

It is when the air drag is starting to take its penalty on a flat bar bike.

 

[pmcdonald]

It is when the air drag is starting to take its penalty on a flat bar bike.

Yeah I agree. Air resistance is likely a lot more of a brake than modern mid drive motor drag. And the higher the motor cut off the more pronounced it'll feel.

Give me a strong tailwind and I can push my 28kg bike up to 45km/h on the flats with effort. (Our cut-off is 25km/h.) With no wind I'd be pushing 28-30km/h at a stretch. Add a headwind and forget about getting above the cut-off at all

 

[GizmoEV]

Try riding it with the power off and also with the battery removed. Compare that with a down hill run, too. If you have a way to see battery voltage, see if it increases when you hit 21mph or so.

 

[Viking1]

The fastest I have had my Bosch is 44mph going downhill on Route 250 atop Afton Mountain heading downhill eastbound. My eyes were watering for sure.

 

[Stefan Mikes]

My eyes were watering for sure.

Didn't you dream of having a warm jacket on you, too?

 

[Viking1]

Didn't you dream of having a warm jacket on you, too?

Not that day! I rode from our RV park up the mountain to the Blue Ridge Tunnel and through it back and forth. Then the fast trip down the mountain.

 

[Jeremy McCreary]

Guys, don't get hung up over that one word. I can much more easily hold 25+ mph, or climb a 12% grade with my acoustic bike than hold even 21 mph, let alone higher on my Bosch class 1.

It requires enormous and unsustainable effort! Clear? I have tried several different gearing ratios / cadences.

Sorry if I missed it — what ebike are you having this trouble with?

 

[AvalancheRun]

Sorry if I missed it — what ebike ate you having this trouble with?

No worries! Gazelle C380 2023 model. Generally it's not an issue, this post was inspired by curiousity as to how the bike works.

There are of course always exceptions, and today was one. Did a new route with some longer hills on the way to an appointment. Man... the Class 1 made it impossible to build usable speed from one hill to another. So I was sustaining 300+ watts going 7-8 mph up long inclines. Only a 6 mile ride in nice weather but I ended up watering the parking lot with my sweat!

 

[Stefan Mikes]

No worries! Gazelle C380 2023 model. Generally it's not an issue, this post was inspired by curiousity as to how the bike works.

There are of course always exceptions, and today was one. Did a new route with some longer hills on the way to an appointment. Man... the Class 1 made it impossible to build usable speed from one hill to another. So I was sustaining 300+ watts going 7-8 mph up long inclines. Only a 6 mile ride in nice weather but I ended up watering the parking lot with my sweat!

Did you ride in Turbo mode? Do not you think the IGH and the carbon belt are less efficient than the derailleur/chain? Did you ride at the cadence > 70?

 

[AvalancheRun]

Did you ride in Turbo mode? Do not you think the IGH and the carbon belt are less efficient than the derailleur/chain? Did you ride at the cadence > 70?

Ordinarily Tour+/Eco. Turbo all the way for this route today. Cadence around 85+ for climbs, high of 110 according to the app. For any serious climbs I’m in the absolute lowest gear the enviolo has.

Definitely considering derailleur next time around.

 

[fooferdoggie]

Ordinarily Tour+/Eco. Turbo all the way for this route today. Cadence around 85+ for climbs, high of 110 according to the app. For any serious climbs I’m in the absolute lowest gear the enviolo has.

Definitely considering derailleur next time around.

that could be it. I can do a 16% grade faster then that putting out 300 or so watts.