Climbing hills on a V20?

[Osiris]

We've been over aspects of this topic before, and I did some analysis (which Dr Parker said he largely agreed with) showing the level of steering movement you'd need in order to get 6.5% of your power from your upper body, given the sample, but representative, MBB bike geometry. It's plus and minus 4.76 degrees. Less than that and you get less than 6.5% power from your upper body, more than that and you'll get more, given the bike geometry that was chosen. As long as your steering angle is oscillating ±4.76 degrees, and the oscillation is timed correctly with your pedaling, that's what you'll get. This is assuming your butt isn't moving around in the seat appreciably.

How much serpentine motion does this cause in the bike's path? At 5 mph, it's around ±0.152 feet, or ±1.83 inches. (If anybody cares how I arrived at that number, let me know and I'll edit this post. It takes some 'splainin.). Why "about" that much? Because there isn't necessarily a one-to-one correspondence between steering oscillation and path deviation, because the bike will roll a little bit in synch with the steering oscillation. But ±2" is probably a good maximum at 5 mph. At 20 mph, it's 4 x 2" = ±8 inches; i.e. it's not gonna work, do not try this, don't say I didn't tell you.

Now you're talking my language. Let me ask you this; do you think it's possible to run tests on a modified trainer to determine exactly how much extra power could be produced in this way? What I have in mind is a trainer resting on a movable base, which would enable the boom to move from side to side while pedaling. To make the test as realistic as possible, the trainer would have to be capable of rocking from side to side. There is at least one manufacturer who makes a trainer with that capability, although the name escapes me at the moment.

 

[LarryOz]

Now you're talking my language. Let me ask you this; do you think it's possible to run tests on a modified trainer to determine exactly how much extra power could be produced in this way? What I have in mind is a trainer resting on a movable base, which would enable the boom to move from side to side while pedaling. To make the test as realistic as possible, the trainer would have to be capable of rocking from side to side. There is at least one manufacturer who makes a trainer with that capability, although the name escapes me at the moment.

Jim Parker just built a wooden base and suspended it from the edges somehow. He has a Wahoo KICKR on it. When he sees this maybe he will post a picture for us

 

[RojoRacing]

the cake is a lie

 

[RojoRacing]

Just a small correction here. I never said anything about climbing a hill at 37 mph. I was talking about sprinting, like it says in the title of Jim's video.

Pff speak for yourself, 37 mph uphill is the best time to swing around the front end

 

[murmur]

I don't quite understand rollers as they're currently marketed, but it seems like they would be the best way to understand the power implications of this "phenomenon". There are some rollers that have variable-drag mechanisms; are there any that claim to do power measurement? Actually it doesn't matter if they do measurement, you can do that with a bike-based power meter.

I don't really think the serpentine motion adds anything significant to the power needed to climb a hill at a given speed, so a roller isn't the only way you could measure power output from this riding mode and have it be relevant.

Here's the problem with all this talk, though: Real-world, or trainer-based, power measurements aren't going to be able to sort out the difference between a change in power due to "turning on" serpentine mode, and a change in power due to your leg muscles getting warmed up or worn down. We already think we know (at least I do) how much power you can extract from your upper body in serpentine mode under the assumptions used to do the analysis from the other thread. Any changes in that 6.5% number are going to be due to:

- Bike geometry changes (the analysis was for a very specific geometry, hopefully not too far from a current Vendetta or Silvio).
- Steering-oscillation changes from the ±4.76 degrees assumed.

So about the best thing we can do is to measure the bike's geometry and measure the rider's steering-oscillation angle, from real-world testing. And maybe strap the rider down in the seat so we know there's isn't moving going on there that would complicate the analysis.

 

[mzweili]

Murmur and Osiris, I like discussions based on facts. Go ahead with your search.

 

[murmur]

wow, things are going to be ok, trplay. Sometimes things just look bleak, right? I get it. Not much you can do but ride it out. Tomorrow's another day.

 

[Rampa]

I get a lot more power on any bike pulling on the handlebars!

I also get a lot more power anytime that I am pulling with my arms directly against pushing with my legs. It's basic human mechanics. What's going on here is the same thing you do playing tug-o-war. Get as horizontal as possible, push with your feet, and pull with your arms. The horizontal part is to get your pull as close to 180 from your push as possible. That is how you are strongest.

The difference on the bike is that you are alternating one leg and opposite arm, then the other. As a thought experiment (or a real one) set both crank arms pointing the same way and try the technique. This would be much like a rowing scull.

 

[Gary123]

That's the way hand cyclist do it.

 

[bladderhead]

Jason has already scooped up all the magic beans

Are they an ingredient of donuts?

 

[LMT]

First and foremost regarding climbing hills on a V20 I'd say lose some weight.

 

[Gary123]

Losing weight and getting in shape is not very interesting. Now back to that "hoochie coochie swivel". That sounds promising. If push pull is of little or no benefit why bother with mbb at all. Other recumbents are much easier to learn and just as comfortable and as fast on flats as cruzbike. Performance on hills is what cb brings to the table and that's hard to argue with no matter what technique is used.

 

[LarryOz]

First and foremost regarding climbing hills on a V20 I'd say lose some weight.

Fastest way to do that - Go to the bathroom at the bottom of the hill...
.... that and turn on your anti-gravity device ....
..... engage .. hyper-drive!

 

[Osiris]

I don't really think the serpentine motion adds anything significant to the power needed to climb a hill at a given speed, so a roller isn't the only way you could measure power output from this riding mode and have it be relevant.

Here's the problem with all this talk, though: Real-world, or trainer-based, power measurements aren't going to be able to sort out the difference between a change in power due to "turning on" serpentine mode, and a change in power due to your leg muscles getting warmed up or worn down. We already think we know (at least I do) how much power you can extract from your upper body in serpentine mode under the assumptions used to do the analysis from the other thread. Any changes in that 6.5% number are going to be due to:

- Bike geometry changes (the analysis was for a very specific geometry, hopefully not too far from a current Vendetta or Silvio).
- Steering-oscillation changes from the ±4.76 degrees assumed.

A 6.5% increase in power would translate into roughly 20 more watts in my case, which I think would be readily apparent when comparing different runs on the same hill. You'd of course have to do each run when fully rested, and do many repeats to get a good idea of your average wattage, but I think the results should be different enough to tell us whether Jim's technique actually produces measurable gains.

 

[MrSteve]

No I'm not done yet. Soon as this push, pull thing finishes being regurgitated all over again I'll introduce my latest technique I stumbled across. It's called the hoochie coochie swivel and it will increase ones power by 12.34632 % . The only problem is recumbent riders will have to give up those 8 inch seat cushions and I doubt they're willing to do that.

It's the only secret I have that's worth keeping.
SShhhhh....

 

[Osiris]

If push pull is of little or no benefit why bother with mbb at all.

Even if we set aside any alleged performance advantage conferred by MBB, I can still cite many features of my V20 which makes it superior to my dearly departed Bacchetta CA2. Every crash I've ever experienced on my other bents was due to pedal interference with the front wheel when executing tight turns. The fact that MBB makes this impossible was enough to sell me on the concept.

Other recumbents are much easier to learn and just as comfortable and as fast on flats as cruzbike.

I'm not sure that's really the case. I've heard a lot of grousing about how difficult MBB is to learn, but in my case it only took one ride to get the pull/push technique down. By the time my second ride was over, I could already ride it just as well as any of my other bents. I would say that it's no harder to learn than the CA2 was, and much, much, easier to learn than my M5 CHR. The M5 is a faster bent by far, but it was an absolute nightmare to learn to ride it without crashing. And don't even get me started on my M1 Lowracer. That bent is wholly unsuited to anything but the race track.

 

[murmur]

trplay, while you're getting the video ready on the Hoochie Coochie Swivel, I'll just mention that the standard MBB serpentine mode will get you 12.34632% more power, but it will take ±9.04 degrees of steering travel. That means managing somewhere close to ±6" of lateral front-end travel for each full crank cycle, at 5 mph. That might be a challenge, so if HCS can get us there, it might be the better route. Since MBB-serpentine is already using some significant core-rotation muscles, I'm going to go out on a limb and guess that HCS involves the muscles of the back. I think we're going to see something that involves a dynamic seat angle, so that you're able to use your back to slide your hips longitudinally. A pelvic-thrust cycle, if you will. Am I right? I bet I'm right.

 

[Osiris]

This is also my case as attested by my video below taken a day or two after getting my first MBB. Not completely accurate since my first MBB was actually a red Radio flyer tricycle I had when I was around two years of age. Reality is, almost all of you first learned to pedal on a MBB. But my question is actually how "much faster by far" is your M5? Can you share the data?

Happy to oblige. I've been collecting data for years on two Strava segment, just to compare the aerodynamic efficiency of my various bikes and recumbents. The first of these is a 0.6 mile segment with an average slope of -1%. It's surrounded by heavy tree growth and a tall berm on one side, which virtually eliminates wind. I cross the starting line at 15 mph and coast to the bottom, noting the top speed each bent reaches. The results have been extremely consistent: the V20 is dead even with my CA2, both topping out at 19 mph. The M5 consistently tops out at 21.4 mph. Now, 19 and 21 mph is still pretty slow, and since since drag increases according to square of your velocity, the M5's aero advantage would increase as speeds go up. Another segment I've used is roughly one mile in length, and perfectly flat. This segment isn't quite as good for consistency, owing to the fact that my speeds will differ depending on my energy level, but have a look at this: Average speed on the V20 @ 327 watts was 24.7 mph. Average speed on the M5 @ 219 watts was 27.3 mph. I've only ridden that segment twice on the V20 so far, so I'll want to get more data, but the difference I've seen between it and the M5 roughly coincides with what I'm used to seeing when comparing the M5 to my CA2. I think it's safe to conclude that the CA2 and V20 are in the same class when it comes to straight line speed, although the V20 has many advantages over the CA2 in other ways.

 

[murmur]

Osiris, 327 watts to do 24.7 mph on a V20? Doesn't square with Larry's 203 watts (all day long) for his 25.05 mph century record in 2015. Being small and having a rear disc wheel and front three-spoke... and maybe better tires... helps. But not by 38%. Even if his meter was reading 17 watts low, that's still almost a 1/3 power reduction relative to your measurements.

 

[RojoRacing]

Average speed on the V20 @ 327 watts was 24.7 mph. Average speed on the M5 @ 219 watts was 27.3 mph.

Yeah that sounds like terrible data when you have Larry is getting 25mph for 200 watts and myself getting 24.5mph for 200 watts. Wait....... are you quoting watts from strava estimates algorithm and not an actual power meter? If so don't look at your wattage number anymore, they will see so far off it's laughable.