Cruzbike power surge using upper body

[Robert Holler]

Im not to s

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.

Jim might have done some actual measuring of this but I cannot recall off hand. My experience is all anecdotal of course as I don't personally run meters/computers/etc of any kind on my personal bikes. But I do ride the exact same hilly loop since 2008 near my house that is 10 miles long and about 800 or so feet of climbing with a few rather steep sections that are in the 50 yards or so length.

On one of those steep sections near my house I have ridden everything under the sun from uprights, LWB recumbents, high racers of nearly every make, SWB's like a P38, trikes of nearly every brand, a small folder, BikeE, a BigHa, a few weird sample bikes (recumbent and uprights) that friends cobbled together, etc.

On this particular climb there were many bikes that I would have to walk up - there was no climbing this hill on most of the bikes even when I was in my best shape. On a few that would make it up, the experience was nothing short of hair raising - where I was riding on the edge of my physical and mental concentration abilities. More than my fair share of times I stalled out 2/3 up and would fall over. many trikes I would lose rear traction or just run out of gas to push.

Enter my first time on a Cruzbike years later. An early model Silvio. After learning to ride it pretty well in the parking lot at the school I went for my loop ride. The hill in question if I go the usual direction is at the end at about mile 9. When I got there I decided to just go for it, and I zoomed up. I did struggle a bit and more than once I had the front wheel slip - but no stalling - I just kept powering to the top arms and legs both going for it. I could barely believe it at the top because bikes I had been riding for years - the ones I was most comfortable on and also lighter - I never went up the hill like that before.

Later after more riding I found that on the Silvio I always had 1 or 2 cogs left to bail out on compared to the other bikes that could tackle that hill I would be in my last and lowest gear, and ALL of those bikes had the same rings and cassette ranges.

Now I don't ride and use this upper body engagement all the time. Mostly my upper body is totally relaxed or just adding input on a near subconscious level - but for my experience when the hills come or I need it, I can muscle the front end and it works.

 

[Beano]

IME you can use the upper body for short sharp climbs and rolling hills. Rolling hills especially are an absolute hoot.

Anything though that is a sustained climb I'd go with a suitable gear and high cadence just using the legs.

 

[LarryOz]

I have ridden many different Cruzbikes with power meters and done much testing- and have been able to look at my data after the fact. As a general rule - you can get 10-20% more power by using the upper body method and this low level can be maintained for basically as long as you have the strenght - usually many minutes. (I usually use it not to get more power, but to maintain my power level and let my legs rest). Those obviously with "more" upper body muscles will be able to last longer. When it's gone you will have to recover - just like any other muscle needs.
If you work on getting stronger upper body then you can impart more power - but generally speaking it will never be as much as your legs (unless your arms look like your legs; haha)
As you practice this technique you will find that you can put larger amounts of power into the drivetrain from your upper body - you just have to train your body to do it and develop the technique and the balance required - but of course you still have a limited amount of power. So you can either use it fast and quick , or slow and longer.

 

[RojoRacing]

IMO the technique or gains from the upper body should be viewed as less about how the upper body can add power. In reality, it's more along the lines of using the upper body to add stabilization so you can push even harder with your legs. Focusing too much on moving the bars back and forth is not going to gain you as much as just focusing on pushing the pedals hard and using your arms to stabilize and keep the wheel straight. When I sprint on the V20 my front wheel moves very little but I am pulling very hard with both my returning foot and arms to keep my ass from sliding up the seat.

Pulling up on the V20 is like how I have to pull up on the single speed mtb for the same reason. On the SS mtb due to the gearing I run compared to the grades I climb, I don't physically have enough body weight to move the bike forward just by just standing one pedal. In fact, if I accidentally unclip one foot mid-climb, the crank with lift me into the air and start sending me backpedalling down the hill. I pull on the bars to allow me to push harder on the pedals, I don't pull on the bars to make more power with my arms. It's a little semantics but when trying to get people to understand stuff like this semantics are important.

I'm also pretty sure my max power on the DF road, SS mtb, V20 outdoors, V20 on trainer are all around 1300 watts in a 10 second sprint so I've never seen any difference in potential max power on any bike.

Now the one thing you could see on a power meter by swinging the boom back and forth would be the length of your power stroke due to you adding 1-2 inches with boom swing. Add length and time to your power stroke won't net you gains just because it's longer, it's just a means to an end because watts are a measure of power over time. You can either push hard for shorter or easier for longer to net the same result.

A good way to understand watts being the results of power over time is understanding the relation of foot/lbs of pressure on the pedal during each cycle vs the wattage measured. Adding a power meter to my SS mtb opened my eyes to this relationship because before I got a PM I always thought I had to be pushing well over 1000 watts on the steep climbs due to how hard I had to push the pedals but that's not exactly true. Imagine a roadie sprinting to the finish line pushing 1400 watts at 120 rpms, let's say he's pushing on each pedal with 200 ft/lbs of downward pressure. Now on my SS mtb I often surge at around 700 watts but only 30 rpms. That means I would be at 400 ft/lbs of pressure because even though I'm producing half the watts, I'm doing it 1/4 as often so I have to push twice as hard each time.

 

[Henri]

foot/lbs of pressure

Preassure would be lbf/ft² (rather in²?), wouldn't it? Are you talking about torgue, which should be ft*lbf? (In metric we call it Nm, Newtons*Meters. I am not sure how things are expressed in imperial, but the math should work the same. )

 

[Bo6]

Great discussion, I too want to understand why I can climb better on my DF than my Q45 and why Cruz is much better than a regular recumbent. Please bear with me as I only have 600 km on my Q45, so I am sure I will get better at climbing. Sorry this post may get a bit long, but feel free to add information and correct my errors.

So looking at Rojoracing's comments. Yes, the terminology is a bit confusing because in the example is 200 lbs of weight or force is put on the on the pedal, not 200 ft/lbs (which is a torque measurement). Watts are a measure of power so going back to high school physics watts = force X distance / time. To get watts a power meter measures the force on the pedal and calculate the watts using the force and distance the pedal moves over the time of the movement.

Units and terms aside it still seems that at a given power (watts) the climbing speed should be the same if all other variables are the same. So what are the variables that affect the work being done and the work needed. Given the same cyclist on both bikes with equal training on both bike types the variables are: ... force on the pedal, pedal velocity (cadence), crank length, bike weight, friction (rolling and wind).

Let's drop wind friction as it is minimal at low speed going up a steep hill. Rolling friction will depend on tires and tire size, but let's use a Q45 and a mountain bike with no suspension and the same size tires so we can eliminate rolling friction as a difference. We'll add weight to the MTB if needed to get rid on the weight variable. We'll use the same Scram 1X12 gearing and crank length to make things as similar as possible and loose the crank length variable. With the same cyclist the watt output will be the same and because watt=force X distance (crank length and cadence) we end up with the force being the only real variable. It's what we all know and feel all the time.

Now I have a hardtail Trek Stash MTB with 3" tires that weighs 30 lbs vs 33 lbs for the Q45. Same gearing on both and the Stash is a slow roller vs the Q45. I know that I can climb steeper hills and faster on the MTB. Wheel slip sets limits the Q45 on steep hills, but I still climb faster on the MTB on a climbable hill. The only variable seems to be the force on the pedals. Now there is a bit of a cheat because the cranks on the Stash are 175 vs 165 on the Q45. I do have to use a lower gear on the Q45 to get the job done though the higher rpm and shorter lever should give about equal watts. The other real variable is the wider bars and longer "lever arm" from standing up on the pedals. It's my suspicion that these longer leavers on the MTB allow me to get more force on the pedals. I also suspect that some larger upper body muscles are being used on the MTB than on the Q45.

As a subscript I had a friend's long wheelbase Burley recumbent and could not climb nearly as well as The Q45.

 

[ratz]

Great discussion, I too want to understand why I can climb better on my DF than my Q45 and why Cruz is much better than a regular recumbent. Please bear with me as I only have 600 km on my Q45, so I am sure I will get better at climbing. Sorry this post may get a bit long, but feel free to add information and correct my errors.

1. Breathing: try to climb on a DF with your chin on your chest.
2. Torque; you have a xxx lbs of extra downward torque on a DF thanks to gravity.
3. De-loading of the off foot: The resting leg gets a micro advantage on DF.

In the end, it's just about Oxygen uptake. That's the one place the DF has an advantage.

Lost in the power meter era.....

Grab an HR monitor and go out and climb. Do four discrete climbs, staring down at your HR rate.

1. DF - Climb at 93% of your Max
2. DF - Climb at 98% of you Max
3. Recumbent - Climb at 93% of your Max
4. Recumbent - Climb...at 98% of your Max

Compare you speeds; and compare your recoverying time.

The Rcumbent at 98% should climb about as fast as the DF at 93%. Most people don't want to push to 98%. Interestingly on a Recumbent you can recover really fast from a 98% effort when you clear the hill; on a DF after 98% the lights tend to go out and you tend to go backwards and it takes longer to recover.

YMMV

 

[Flying Dutchman]

Very interesting discussion.

It made me wonder the maximum power one can put through by pushing against the back. This possibly doesn't so much work on the V20 but on the Q45 you certainly should be able to get some leverage, a bit like a leg press in the gym. I know that in the gym I can push somewhere around 130 - 150% of my body weight. But note of course that those a slow movements so that would only work for (very) low cadence. But it does mean that you should be able to push an enormous weight in that position, I would imagine a much greater weight than you could ever do on a DF as there you only have your full body weight that you can get onto your pedal. So if you for example try to pull a weighted sleigh, you should be able to pull heavier on a Q45 than you can on a DF.

That should also translate into riding off in very low gears. Of course there you would have the balance issue and again the wheel spin. But I can imagine designing a recumbent that utilises this principle.

Who knows

 

[ratz]

Very interesting discussion.

It made me wonder the maximum power one can put through by pushing against the back. This possibly doesn't so much work on the V20 but on the Q45 you certainly should be able to get some leverage, a bit like a leg press in the gym. I know that in the gym I can push somewhere around 130 - 150% of my body weight. But note of course that those a slow movements so that would only work for (very) low cadence. But it does mean that you should be able to push an enormous weight in that position, I would imagine a much greater weight than you could ever do on a DF as there you only have your full body weight that you can get onto your pedal. So if you for example try to pull a weighted sleigh, you should be able to pull heavier on a Q45 than you can on a DF.

That should also translate into riding off in very low gears. Of course there you would have the balance issue and again the wheel spin. But I can imagine designing a recumbent that utilises this principle.

Who knows

It's called "bridging" dig shoulders in; lift butt; and PUSH; just watch the knees it's the one thing that makes what you are thinking about a bit hard on the body.

 

[RojoRacing]

Preassure would be lbf/ft² (rather in²?), wouldn't it? Are you talking about torgue, which should be ft*lbf? (In metric we call it Nm, Newtons*Meters. I am not sure how things are expressed in imperial, but the math should work the same. )

The engineer at rotor I was dealing with stated some kind of value but I don't recall what it was. I tried to calculate it myself but gave up because in the end understanding the implication was the important part. Explaining why climbing on a SS feels so hard even if the measured effort is the same and knowing why I shouldn't run aluminum chainrings was enough.

 

[alexul]

The engineer at rotor I was dealing with stated some kind of value but I don't recall what it was. I tried to calculate it myself but gave up because in the end understanding the implication was the important part. Explaining why climbing on a SS feels so hard even if the measured effort is the same and knowing why I shouldn't run aluminum chainrings was enough.

Thanks a lot for clearing the initial assumption that is more related to stability rather than power coming from upper body. While it's intuitive for FWD I would like to know if it's the case also for RWD. The front wheel is not directly connected to the drivetrain. I started riding an used RWD and when I push really hard, lifting my butt and against the seat my arms are quite relaxed, I don't feel the need to stabilize anything unless I'm going very slow.

 

[Bo6]

I had a friends LWB rear wheel drive (Burley) and fond the same thing. In fact, if I pulled on the bars, it de-stabilized the bike and created a wobble. I found relaxing my upper body gave the best hill climbing performance.

Pulling the bars on the Q45 allows me to engage my core while stabilizing the steering. This seems to help increase my power and may be part of why I find the Q45 a better climber. It also makes getting away from stop signs easier.

 

[Beano]

Great discussion, I too want to understand why I can climb better on my DF than my Q45 and why Cruz is much better than a regular recumbent. Please bear with me as I only have 600 km on my Q45, so I am sure I will get better at climbing. Sorry this post may get a bit long, but feel free to add information and correct my errors.

There has been research on this,

Effect of low recumbent angle on cycling performance, fatigue, and V˙O(2) kinetics - PubMed

Lowering the recumbent angle to 15° resulted in shorter performance, larger fatigue, and altered V˙O(2) kinetics.

pubmed.ncbi.nlm.nih.gov

There are other articles as well.

In a nutshell:-

The more laid back on your bike you are the lower your hydrostatic pressure is.

As a result of this the stroke volume of your heart goes up, this will lead to an increase in heart rate as you compensate for the reduction in hydrostatic pressure.

So when putting out an effort and getting up to your LTHR (lactate threshold heart rate), given your stroke volume is already higher on a recumbent than a DF this will impact your VO2 max and the max power you can put out.

There are other things as well, DF are lighter which makes a difference when going up a climb, more so when that climb is greater than 8% which is where weight of a bike plays a big part.

 

[vosadrian]

I ride a V20 and an upright about the same amount of time per week. I am MUCH slower up hills on the V20 (like several minutes up a climb I do in 10 minutes on the DF). I am MUCH faster down hills and on flat roads on the V20. I get up to speed from a stop MUCH faster on the DF. My average power outputs tend to be around 10-15% less on the V20 for same perceived effort. My peak power on the V20 is about half what I can do on the DF.

 

[LarryOz]

I ride a V20 and an upright about the same amount of time per week. I am MUCH slower up hills on the V20 (like several minutes up a climb I do in 10 minutes on the DF). I am MUCH faster down hills and on flat roads on the V20. I get up to speed from a stop MUCH faster on the DF. My average power outputs tend to be around 10-15% less on the V20 for same perceived effort. My peak power on the V20 is about half what I can do on the DF.

Curious - Do you have a standard course you ride that has that "climb the you are much faster on the upright on"? How does your total time around the entire course compare between the Upright and the V20 - both in avg power and time.
Much testing has been done with climbiing between standard upright and Cruzbikes - if the bike and rider weight the same - and the climbing is 5 % grades or less - the avg power to do the climbs are virtually the same.

So when putting out an effort and getting up to your LTHR (lactate threshold heart rate), given your stroke volume is already higher on a recumbent than a DF this will impact your VO2 max and the max power you can put out.

There are other things as well, DF are lighter which makes a difference when going up a climb, more so when that climb is greater than 8% which is where weight of a bike plays a big part.

I have also done much testing in this area - and have proven it is much easier to make power the higher the seat angle. If you have a climbing course you will do much better on an S40. If you are mostly flat and rolling the V20 will gobble it up.

 

[vosadrian]

Curious - Do you have a standard course you ride that has that "climb the you are much faster on the upright on"? How does your total time around the entire course compare between the Upright and the V20 - both in avg power and time.
Much testing has been done with climbiing between standard upright and Cruzbikes - if the bike and rider weight the same - and the climbing is 5 % grades or less - the avg power to do the climbs are virtually the same.


I have also done much testing in this area - and have proven it is much easier to make power the higher the seat angle. If you have a climbing course you will do much better on an S40. If you are mostly flat and rolling the V20 will gobble it up.

I have standard courses I do on my bikes. As time has gone by, I typically use different courses for the different bikes and now I rarely ride the same course on both bikes. I live in a hilly area and I live in a valley. Typically I can do 100m elevation before I ride 2km from my house. Every ride I do pretty much has 1000m elevation per 100km of riding. So my area is not as well suited to the V20 compared to most people who ride them. Typically climbs for me are 5-15%, but I know I could not keep up with my DF climbing speed even on 3-4% on the V20. I am talking sustained climbs here... not rolling hills. Climbs where your HR stabilises and you lose your momentum and are going for >5 minutes at constant gradient. 5% on the DF for me is 20-25kph. V20 would be 15-20kph.

So in answer to your question, yes, I have tested both on a local climb and I am much slower on the V20, and even then I feel I am working harder. These climbs I am typically going in the 10-20kph range, and the aero deag is just a small proportion of total power. If I make lower power, and push a bike that is double the weight, I am going to go much slower as expected.

Of course, because of this, I go searching for flat roads on the V20.... this means about 5-10km of hills to find flatter roads. On those roads, I am MUCH faster on the V20. It is what it is made for. On the DF I go looking for hills. Horses for courses. So I could show you courses I ride where I am faster on the DF and others I ride where I am faster on the V20.

I am sure the other CB options are better at climbing then the V20. But I can assure you, that I would not be able to come close to matching my times of my 7kg DF road bike on any recumbent be it CB or anything else. The DF allows my to optimise my body to get the most of it. I can move around a alot to spread the muscle fatigue to different groups which is the main benefit to me and enables me to get higher power outputs on DF then recumbent.... and I have not seen a 7kg recumbent yet.

I don't doubt your claim that if CB bike + rider weight is the same that average power is about the same...... But rarely is the weight going to be the same (V20 is 14kg vs my DF at 7kg).... and most riders will do more power in an upright position (I certainly do).

 

[CruzRider]

I have standard courses I do on my bikes. As time has gone by, I typically use different courses for the different bikes and now I rarely ride the same course on both bikes.

I have employed my bike stable in the same way. Sadly, I cannot ride my DFs even for short distances right now. The one exception being my Rivendell Cruiser.

I have found that even though I cannot put out as much power on my CruzBikes (estimated 20% loss), I can ride with less fatigue (or is it more comfort?) about 100% longer on a decent road surface. I feel the CruzBike comfort advantage melting away on a rough surface, because I cannot be as nimble or sit up.

I can see how the CruzBikes have an advantage when used for Ultra-Cycling, with the DF having an advantage on shorter rides. Relatively speaking for the same rider.

Much like you though, I do not foresee ever giving up my CruzBikes even when I am able to ride my Drop Bar DFs.

 

[vosadrian]

@CruzRider, I think we are much the same. My back is the reason I got the V20. It enables me to ride the kms a week I want to ride that I just can't do on a DF anymore. I make less power, but my speeds are faster as I choose to use the V20 on roads that suit it. I can go about twice as far on the V20 compared to DF due to my back limitations. Like you, I prefer smooth roads on the V20.

I believe the CB is a very good recumbent for climbing, but I just can't see how anyone could go faster up (proper) hills on them compared to DF if they were having a good go on both. I rode the V20 exclusively for about a year. If anything, I had bent legs and had not maintained my DF legs. I then decided to get out the DF again. On the first ride I cruised (moderate effort) up a hill I did regularly on the V20 in a faster time than I had ever done on the V20 at full effort. Of course my DF is a very good DF and that comes into it... but my V20 is not exactly poverty spec.

 

[Frito Bandito]

On BROL there was a pretty good discussion with Steamer who plugged in some numbers to gauge how well me on my V20 climbs against me on my DF bike, and without going into too much data because that is out of my paygrade, in a best case scenario my V20 climbs faster than my DF on grades up to almost 3%. What I mean by "best case" is when max power is used because then it is fast enough for the V20s better aerodynamics to factor in. Anything above 3% and the DF starts pulling away. The higher the slope the more quickly my DF pulls away. When power is dropped to about 80% of FTP the break even grade seems to be about 2.3%. I was a bit hopefully guestimating that the break even grade would be about 5% but I am pretty sure that was a bit optimistic. Now, of course this is comparing apples to oranges, but I was curious to find out what that grade was. What would be interesting to see is a V20 against some of the other bents in the same class, and even against low racers.

We didn't get into the V20's higher descent speed any at all, but I suppose it would be nice to know what the results would be for the total ascent and descent to see if or by how much of an advantage a V20 would have. One thing to note would be not only the grade but also route. Long swooping curves or short switchbacks? All of that is getting WAAAAAAY too deep for my noggin so I'll just stop there. What I do know is that regardless of the results my V20 can handle whatever I throw at it, and if there is some discrepancy I know where the problem lies.

 

[vosadrian]

In my area, the hills I ride my DF on are technical with switchbacks etc. Mostly you can see more than 100m up the road because they are very windy roads. I am more confident on my DF, so I doubt in this case I could go quicker on the V20. Probably slower. Of course the V20 is much faster on more open descents if you have access to them.

I would have guessed I was quicker on the V20 up to about 2-2.5%. Above that you are just not going fast enough for aero to be a factor.

A climb near me is about 10 minutes with an average of 5.6%. On my DF, I am in the top 1.5% on Strava out of about 20,000 riders including many pros. My average speed for that effort was 21.5kph. That is just not fast enough for aero to be a factor.