Cruzbike power surge using upper body

[jeffTrinkle]

Hi All,
I'm a new Cruzbike owner and curious to learn from the experience of long-time Cruzbikers. Please help me understand the following comment I saw on the Cruzbike webpage:
"it [a Cruzbike] links the upper and lower body across the drivetrain as it rotates around the axis of the head tube. This linkage allows Cruzbike riders to increase power when climbing or sprinting by engaging the upper body in much the same way professional cyclists do when they climb or sprint on traditional road bikes."

To me it seems like my upper body works against my legs to stabilize the front wheel and not to increase power to the drive wheel. I don't see how I'd be able to increase the power like I get on my road bike when climbing out of the saddle.

I'd love to hear your experience.
Thanks
jeff

 

[Mathew Fy]

Jim explains this concept more in this video:

I don’t know how much advantage you get from this, but I believe more energy is sent to the wheels, making Cruzbikes very efficient.

 

[CruzRider]

I have had some limited success with this method, on mild inclines. In my experience, and as I have read on the forum, the trick is to pull against the handle bars in an effort to return the front wheel back to center. It certainly feels like the hands are adding more power into the system. I see the potential, but I have by no means mastered it.

 

[jeffTrinkle]

Thank you for your replies. The video was helpful. Now I see the theory and am wondering about testing it. I have a pair of pedals that measure power produced by each leg. If I install them on my Cruzbike (and become expert enough to ride as shown in the video) then perhaps I could verify the theory. I’m thinking I could do test rides with the power pedals on a Cruzbike and a rear-wheel drive recumbent, like a Bacchetta. Then I could compare the data. What do you think?

 

[Always-Learnin]

Thank you for your replies. The video was helpful. Now I see the theory and am wondering about testing it. I have a pair of pedals that measure power produced by each leg. If I install them on my Cruzbike (and become expert enough to ride as shown in the video) then perhaps I could verify the theory. I’m thinking I could do test rides with the power pedals on a Cruzbike and a rear-wheel drive recumbent, like a Bacchetta. Then I could compare the data. What do you think?

I'd say, go for it and report back...

 

[Tuloose]

I have had some limited success with this method, on mild inclines. In my experience, and as I have read on the forum, the trick is to pull against the handle bars in an effort to return the front wheel back to center. It certainly feels like the hands are adding more power into the system. I see the potential, but I have by no means mastered it.

When I really start haulin A on my Cruz I'm pushing hard on the pedals and counteracting that force with a firm pull on the handlebar.

I call this maneuver yanking and cranking.

 

[jeffTrinkle]

Thanks guys. When I'm skilled enough to clip in and do the "yanking-and-cranking maneuver," I'll install my Garmin Rally pedals to measure the power and let you know what I find.
Cheers.
jeff

 

[LarryOz]

It really does work - It even works on a trainer, and if you are using something like Zwift you can actually see your power going up when you use your upper body.
The caveat to this hole this is that you can't get nearly the power you can out of an upright bike. I think this is due to the fact that you don't have gravty to help you. Your upper body will also tire out way quicker than you legs, but if you use your upper body occasionaly you can give you legs a minute or 2 rest, which sometimes makes all the differnet you need to keep going.

 

[jeffTrinkle]

It really does work - It even works on a trainer, and if you are using something like Zwift you can actually see your power going up when you use your upper body.
The caveat to this hole this is that you can't get nearly the power you can out of an upright bike. I think this is due to the fact that you don't have gravty to help you. Your upper body will also tire out way quicker than you legs, but if you use your upper body occasionaly you can give you legs a minute or 2 rest, which sometimes makes all the differnet you need to keep going.

Hi Larry,
Thanks for your points. I don't use Zwift and don't have a smart trainer, so I'll take your word for it. And it makes sense that you can get more power out of the saddle on a normal road bike. I agree that gravity helps, but I think there's another effect you can get on a normal road bike that helps - you can lean the bike left and right while your body stays upright to keep your legs in their power positions longer. With the Cruzbike, I can't lift my body off the seat and still pedal, so I can't shift it left and right under me.

 

[vosadrian]

I'm not sure what you are going to prove with a Garmin PM. I have been running Garmin PM on my V20 for tens of thousands of kms. I don't find the dual pedal to mush use as I am always very close to 50:50.

The simple fact with a bike like this is that if you push harder with you legs, you are going to have to counteract the leg torque on the steering with an oposing force on the handle bars. In my case, I find that even when using a lot of upper body, my steering is hardly moving.... all the upper body strength goes into trying to leep the wheel straight... maybe I am doing it wrong and should pull harder to make some movement. I'm not sure how the PM is going to allow you to isolate any benefits from the upper body.

In the case of a normal DF bike (which I have lots of experience on and I am more of a sprinter who does standing sprints often), I think the advantage is being misunderstood. On a DF when you are in a standing position, you tilt the bike over so the pedal you are pushing down on goes upwards against the downward push of the pedal. As a result the legs do not moves as far to complete the crank rotation. Some simple high school physics (W=Fs) will prove that you are using less energy in your legs to produce the same force over a shorter distance. You have moved some of the energy to the upper body (which levers the bike from side to side). it is less about the steering from side to side, and more about tilting the bike over.

On a cruzbike, you' don't tilt the bike like a DF... but you are pushing the pedals out rather than down due to reclined position, so I guess moving the steering from side to side could have similar effect?

 

[Henri]

My intuition would say something similar to @vosadrian , that you could take pedaling distance away from the feet and kind of increase oedaling frequency with that.

Another thing that could happen on a confentional bike when you go out of the saddle is longitudinal movement. In the power position of the kranks push your own body weight forward to increase force and acceleration, in the weak position pull your bike forward to overcome that position more quickly and get into the next power position. I noticed I made heavy use of lateral movement ot slow speeds in my single speed folding bike. So this technique might be most advantageous on a sprint to start it in a high gear and sit back down, ince you got your cadence up. (And to get up a climb, when your gears are too hard.)
That's why I use oval chainrings now.
On any recumbent I use a riding style for sprints and when I am fatigued, where I lift my butt, spanning an bridge from the shoulder part of the seat to the pedals. Whith this I can also very effectively push a very high gear while raising and lowering the bridge. Maybe the changing body position also changes my angle of attack on the pedals and helps me shrink the weak spot?

Also cranking produces lateral forces and moments that you have to stabilize against. In a saddle you have some lateral support, but it's mainly from the inside if your thigh, that is then rubbing, because you are pedaling ar the same time. So you are supposed to keep your body stiff and derive lateral stability from your hand-handlebar-connection. But that stability travels through a big triangle from your hands around your butt to your feet. When standing up, you "flatten" that triangle, get your butt closer to the line between handlebars and cranks. On a recumbent your handle bar is already closer to your hip, but on most other designs it is not a strong source of stability. On Cruzbikes with their "patented front triangle drive train thingamajig" it actually is and it can give you a great amount of stability on the bike. (Especially if you lost a lot of seat support by lifting up your butt - which is than again closer to the handle bars, flattening the support triangle even more.)
The side to side motion when riding ot of the saddle might rather be to get you in a spot from where you can push the pedal with as little lateral consequences as possible ("straight down" from you center of mass) So steadying the front triangle against sideways motion might very well as much be steadying yourself against pushback from the pedals.

Also there is body angle on a climb. conventional bike riders say, they dont like the feeling if being leaned back on a steep climb and actually lose power because thebforces and dynamics aren't the same anymore (Not the situation the bike geometry is set up for or just not used to that situation?) On a recumbent there is also the hight of feet and heart and head, where on a steep climb your circulation system might have some challenge to distribute the blood ideally. Training in that position surely helps, but also lifting your upper body to sit more upright. This also sharpens the angle between body and legs, which many say increases their pedaling force->torgue->power. For this maneuver a stable handlebar is also highly advantageous, especially when it's also rotationally stable with the cranks.

 

[jeffTrinkle]

I'm not sure what you are going to prove with a Garmin PM. I have been running Garmin PM on my V20 for tens of thousands of kms. I don't find the dual pedal to mush use as I am always very close to 50:50.

The simple fact with a bike like this is that if you push harder with you legs, you are going to have to counteract the leg torque on the steering with an oposing force on the handle bars. In my case, I find that even when using a lot of upper body, my steering is hardly moving.... all the upper body strength goes into trying to leep the wheel straight... maybe I am doing it wrong and should pull harder to make some movement. I'm not sure how the PM is going to allow you to isolate any benefits from the upper body.

In the case of a normal DF bike (which I have lots of experience on and I am more of a sprinter who does standing sprints often), I think the advantage is being misunderstood. On a DF when you are in a standing position, you tilt the bike over so the pedal you are pushing down on goes upwards against the downward push of the pedal. As a result the legs do not moves as far to complete the crank rotation. Some simple high school physics (W=Fs) will prove that you are using less energy in your legs to produce the same force over a shorter distance. You have moved some of the energy to the upper body (which levers the bike from side to side). it is less about the steering from side to side, and more about tilting the bike over.

On a cruzbike, you' don't tilt the bike like a DF... but you are pushing the pedals out rather than down due to reclined position, so I guess moving the steering from side to side could have similar effect?

@vosadrian... I agree with your ideas about the effects of DF tilting, etc. I also agree that the Garmin PM will not tell me how much power is coming from my upper body, but it CAN tell me how much power is delivered to the cranks. Our discussion is based intuition, experience, and "theory," a PM could give real power data to verify or refute that one can truly deliver more power to the cranks on front-wheel-drive than on rear-wheel-drive recumbents. The plan would be to ride Cruzbike on a certain route with hills and measure power. Then move the PM to a Bacchetta (or other rear-wheel-drive recumbent) and ride that bike over the same route. On both routes I'd have to try to ride with the same intensity, have the same fitness, and similar wind conditions. This is easier said than done, but if the Cruzbike is significantly more efficient on the climbs, I would expect this to show up in the power data (and climb times). If I can't see it in the data, then I would say the effect is too small for short rides, but still could be important for long endurance rides.

 

[jeffTrinkle]

My intuition would say something similar to @vosadrian , that you could take pedaling distance away from the feet and kind of increase oedaling frequency with that.

Another thing that could happen on a confentional bike when you go out of the saddle is longitudinal movement. In the power position of the kranks push your own body weight forward to increase force and acceleration, in the weak position pull your bike forward to overcome that position more quickly and get into the next power position. I noticed I made heavy use of lateral movement ot slow speeds in my single speed folding bike. So this technique might be most advantageous on a sprint to start it in a high gear and sit back down, ince you got your cadence up. (And to get up a climb, when your gears are too hard.)
That's why I use oval chainrings now.
On any recumbent I use a riding style for sprints and when I am fatigued, where I lift my butt, spanning an bridge from the shoulder part of the seat to the pedals. Whith this I can also very effectively push a very high gear while raising and lowering the bridge. Maybe the changing body position also changes my angle of attack on the pedals and helps me shrink the weak spot?

Also cranking produces lateral forces and moments that you have to stabilize against. In a saddle you have some lateral support, but it's mainly from the inside if your thigh, that is then rubbing, because you are pedaling ar the same time. So you are supposed to keep your body stiff and derive lateral stability from your hand-handlebar-connection. But that stability travels through a big triangle from your hands around your butt to your feet. When standing up, you "flatten" that triangle, get your butt closer to the line between handlebars and cranks. On a recumbent your handle bar is already closer to your hip, but on most other designs it is not a strong source of stability. On Cruzbikes with their "patented front triangle drive train thingamajig" it actually is and it can give you a great amount of stability on the bike. (Especially if you lost a lot of seat support by lifting up your butt - which is than again closer to the handle bars, flattening the support triangle even more.)
The side to side motion when riding ot of the saddle might rather be to get you in a spot from where you can push the pedal with as little lateral consequences as possible ("straight down" from you center of mass) So steadying the front triangle against sideways motion might very well as much be steadying yourself against pushback from the pedals.

Also there is body angle on a climb. conventional bike riders say, they dont like the feeling if being leaned back on a steep climb and actually lose power because thebforces and dynamics aren't the same anymore (Not the situation the bike geometry is set up for or just not used to that situation?) On a recumbent there is also the hight of feet and heart and head, where on a steep climb your circulation system might have some challenge to distribute the blood ideally. Training in that position surely helps, but also lifting your upper body to sit more upright. This also sharpens the angle between body and legs, which many say increases their pedaling force->torgue->power. For this maneuver a stable handlebar is also highly advantageous, especially when it's also rotationally stable with the cranks.

@Henri You have a lot of skill and insights that I don't yet have the skill to experience. It would have never occurred to me to lift my ass off the seat of a Cruzbike while pedaling. Wow.

I agree with your intuition about tilting a DF bike while sprinting or climbing out of the saddle. Back to my response to Vosadrian, I'd like to actually test what we've been talking about. As you pointed out, there are many subtle things skilled riders do to increase power for a short time or just change the load on the various muscles to "rest" them. I hope I can find someone who will let me use their rear-wheel-drive recumbent to do the testing I described above.

Cheers.

 

[Henri]

On any recumbent

Oh, need to correct that: Seat angle and bottom bracket hight need to be right. Just meant it doesn't matter if fixed or moving bottom bracket.

And sure, measurements would be great. Should always do multuple runs to get an idea of tun-to-run variance. I would think about it, too, but my bikes are too different to give a good comparison and I am probably too inconsistent. Although I already have powermeter on some, so I could do a few runs and then swap the meters to look for a bias from differently reading meters. Hmmh.

 

[vosadrian]

I think you could test it if you have access to the same PM (I find different brands read differently) on two different bikes (one FWD and one RWD) with the same basic bike fit (so your body is operating at the same efficiency). I think you would need to be riding at a stable fitness level and just do your regular rides, but do a few with one bike and a few with the other and make sure you do not improve or lose fitness throughout the testing. Then make it blind by recording the PM data but not viewing it while riding. Ride to heart rate and try to keep it the same on each bike, and on hills try to keep perceived effort the same. Set some Strava segments for different types of riding (up hill, flat) and compare the results!

 

[jeffTrinkle]

I think you could test it if you have access to the same PM (I find different brands read differently) on two different bikes (one FWD and one RWD) with the same basic bike fit (so your body is operating at the same efficiency). I think you would need to be riding at a stable fitness level and just do your regular rides, but do a few with one bike and a few with the other and make sure you do not improve or lose fitness throughout the testing. Then make it blind by recording the PM data but not viewing it while riding. Ride to heart rate and try to keep it the same on each bike, and on hills try to keep perceived effort the same. Set some Strava segments for different types of riding (up hill, flat) and compare the results!

Agreed. I would use my same Garmin PM and paired 530 computer on both bikes. Riding to heart rate should help me make similar efforts. Now I need to find someone with a large frame Bacchetta who will let me use their bike for a while. There are a bunch of Bacchettas on rides I go on, but no Cruzbikes (except me).

 

[Rolling Along]

I am a new V20c rider at just over 750 miles. I also have a large frame Bacchetta CA2 and I have over 18,000 miles of riding experience on it.
Initially, I was much faster on the CA2. But as I gain experience riding the V20c the speed gap closes. I am almost equal for what I feel is the same effort. But I have no power meter to test.

What I like about the V is that I can pull on the handlebars as expressed on this thread to counteract a strong push on the pedals. This lets me go from stopped to a decent speed in what I perceive is less time than on the CA2. I can also use the handlebar pull technique to try for max speeds.

One thing to point out is that if comparing bikes, you need to consider how they are configured. For example, I have a Brainbox on the back of my
CA2 and I have carbon wheels with the back one being a trispoke. I consider the wheels of my CA2 to be faster than the stock wheels I have on the V20c. I have Maxxis tires on the V and Continental tires with one width different on the CA2. I also have the CA2 seat reclined to about the same as the recline on the V20c. But I could lower/raise the CA2 seat as desired. Last, I could also take the large pump and tools I carry in the Brainbox out to reduce weight. Anyway, you get the idea as far as configuration.

 

[vosadrian]

You could not do this as a speed comparison between different bikes. It would have to be comparing the power numbers for perceived effort or HR. On my V20, I picked up about 3kph improvement in average speed on my rides going from stock wheels to some 88mm deep carbon wheels with tubeless tyres.

 

[alexul]

I am also curious why it's complicated to back their claim using hard numbers. All this theory and slow motion clips looks nice but why not have the same rider on a cruzbike and another bike, same powermeter installed on both and show the generated power. Afterwards come drivetrain efficiency which I believe is better on a cruzbike, aerodynamics, seat support etc but if we talk strictly by power to the pedal there is only way to measure it.

 

[CruzRider]

I have some power meter pedals on the way and will be trying to test this out. I am sure people will have a problem with any methodology I use.

Intuitively, it is easy to see how holding one foot out and pulling back on the handle bar with the opposite hand will show a power meter reading. The question then is not if, but how much power can be generated with this technique while riding safely.