MBB drivetrain vs others, a poll (with a twist).

[Balor]

I have a pet theory why MBB drivetrain is objectively superior to RWD or FWD-TC, but I lack data.

I'll explain it later (to avoid polluting the data), but for now I'll ask people to provide some comparative analysis on their power levels (of possible) and/or climbing speed compared between DF, FWD-MBB (that is what Cruzbikes are, forward drive - moving bottom bracket in case you don't know ) and RWD or FWD-TC (twist chain) recumbents AND state their BMI.
http://www.whathealth.com/bmi/formula.html

I know that is a bit of a personal data, but please do it "For Science!"?

For instance:

I have BMI of about 30, I can nearly match myself climbing on my MBB compared to DF (which is much lighter, of course), and but power/speed drop when climbing on RWD is about 30%.

 

[McWheels]

Right you are. BMI 26.4, % bodyfat about 12 (might help), but I'm on a V2k with a fairly upright seat and some pretty hefty hubs; dynamo and SA 8-Sp. I've no comparison to RWD except against a TerraTrike Cruiser I borrowed for a race, although it's pretty clear I'm faster now, especially any slight inclines.

Vs the previous DF I'm not as quick up a hill, I think it also comes down to resistance to motion in weight. The DFs were much lighter with 700c x1" wheels vs 26"x1.25". I think speed wise we're pretty similar on the flat (17-20mph). I'm at 650 miles on the current bike so maybe the next few weeks of persistent commuting will pay a few more dividends. I've since moved, but the hill on the way home from previous place of work was quite steep and I could manage a sustained DF 10mph up it. Now I reckon 7-8 tops.

 

[Balor]

Speed on the flats is dependant on CdA, and since exact CdA values are extremely hard to calculate it is mostly useless, unfortunately.
Trike is not exactly a fair comparison, too, you need to account for crr from extra wheel and the weight...
Anyway, I AM about as fast on my MBB as on my DF now, so I think you'll see similar dividends.

Anyway, I'd very much like to see more data and MBB/RWD/DF comparisons.

 

[Bill K]

When my V20 was brand new (Dec. 2015) I did some comparisons between my bikes. I wanted to see if my spiffy new V20 would live up to its touted climbing capabilities.
This was my conclusion written up at the time.
Note that when I wrote this I had only ridden the V a few times. I could not pedal and steer at the same time so climbing a hill was less than efficient.

The Vendetta compares pretty well with my Davidson DF (my rando bike, a custom ti touring bike which weights about the same as the Vendetta: 28#).
It also does pretty well against the Bacchetta Giro, probably better but I do not have enough data to have any confidence in the numbers yet.
Here is the comparison in Strava:
https://www.strava.com/segments/1544017/compare/MTA4MjU2MDA3MzgsMTA2MDM0MzQzNzMsMTA5MDUyNDE4NzE=

12/14 is the Davidson: Average power was 208 watts.
11/28 is the Bacchetta: Average power was 219 watts.
12/20 is the Vendetta: Average power was 189 watts.
The Bacchetta had a running start (gains 10 seconds at the bottom) and the other two did not, so the numbers are a bit bogus.
With a running start, and with an additional 30 watts the Bacchetta was faster by maybe 5 seconds. Once I can ride the V without wobbling (and cutting power to regain control) I expect it will be considerably faster.
I used the same power meter on all three bikes: a Power2Max crank.

Fast-forward to today:
My BMI = 21
A 200 watt effort on the V20 is about the same perceived effort as 220 watts on the DF (I still ride both bikes on a regular basis).
Since then, the V20 has broken all my Strava PB's on my regular rides - both flat and uphill segments (and with about the same power).
Here is some data for some of my rides on the above segment.
In case you are interested, I tested the Giro with a conventional transmission (Sram X9) and with a Rohloff hub. I found a significant difference between their efficiency in low gears.

Bike Power Speed Cad HR Time Gear Date
Davidson 2 222 12 92 158 4:08Ultegra 10-spd 12/14/14
Davidson 2 194 10.3 91 145 4:48 12/14/15
Davidson 2 208 11.5 90 153 4:17 12/14/15
Bacchetta 228 10.5 83 148 4:43Rohloff 12/12/14
Bacchetta 219 10.3 82 139 4:47Rohloff 11/23/14
Bacchetta 222 10.3 82 4:48Rohloff 12/7/14
Bacchetta 219 10.4 88 148 4:46Rohloff 11/28/15
Davidson 1 230 12.7 89 3:54Ultegra 10-spd 9/16/12
Davidson 1 225 12.2 91 4:04 5/6/12
Davidson 1 210 12 87 141 4:08 4/22/12
Davidson 1 229 12.4 95 158 4:00 12/30/12
Bacchetta 225 11 87 157 4:30Sram X9 12/17/14
Bacchetta 231 11 86 152 4:29Sram X9 12/17/14
Vendetta 189 9.5 88 155 5:12 12/14/15
Vendetta 186 10.2 88 159 4:52 1/1/16

 

[Balor]

A 200 watt effort on the V20 is about the same perceived effort as 220 watts on the DF (I still ride both bikes on a regular basis).
Since then, the V20 has broken all my Strava PB's on my regular rides - both flat and uphill segments (and with about the same power).

Stands to reason - aero works all the time.
Do you still have Bachetta? The 'same power' bit seems very interesting and somewhat surprizing.
So it seems for same power AT THE CRANK Bachetta is about 1.2 Mph slower uphill than DF. How heavy it is? Or maybe drivetrain losses are greater than I've thought?
Oh wait, giro is 26" recumbent, right? The extra CRR of touring tires can easily account for that much.

In case you are interested, I tested the Giro with a conventional transmission (Sram X9) and with a Rohloff hub. I found a significant difference between their efficiency in low gears.

Yea, about 5% loss of efficiency, that is to be expected.

 

[Bill K]

So it seems for same power AT THE CRANK Bachetta is about 1.2 Mph slower uphill than DF. How heavy it is? Or maybe drivetrain losses are greater than I've thought?
Oh wait, giro is 26" recumbent, right? The extra CRR of touring tires can easily account for that much.

The Giro is about 35#: ATT-26, 26 x 1.5 tires, fenders, dynohub, brainbox with stuff in it. Tires were Compass "McClure Pass", seat at about 35deg angle, rigged for commuting.
Definitely not your go-fast stuff!