Road bike vs. recumbent comparison

[Osiris]

Boom swinging IS a valid way of actually adding power via upper body, but how much can it contribute is an other open question, I don't do it much myself.

When I first inquired about this, two forum members sent me a PM addressing the question. One said that it does work for him, although he wasn't sure how much, and that it's only useful for short intervals. The other told me that it's just marketing hype. Both of them are successful V20 racers. I remain skeptical about the alleged benefits, but IF it works, then it seems to me that hard evidence would be pretty easy to produce: just read the power meter. It's a bit odd that after all this time, we still have nothing to go on but uncorroborated opinions.

 

[Balor]

Well, it works and it works the same way rocking the bike side to side on DF works: using your upper body to effectively 'press' the pedal into your foot, producing additional torque. A rather simple physics, actually, no tricky biomechanics about it.
I guess, if one is mechanically inclined, one can even draw diagrams and force vectors and calculate exact benefit one derive from each degree of 'bar swinging' or 'bike rocking'.
Point is, the benefit is likely small.
Being able to combine short chain, large front wheel and low BB with low(ish) seat is certainly unique to MBB though.

 

[DavidCH]

I've been tilting my saddle on a DF recently and lowering the bars. Getting more power now. Like most sports ... it's technique and tinkering with marginal gains that makes it all rewarding. Not quite as fast as these guys yet...

 

[Osiris]

Well, it works and it works the same way rocking the bike side to side on DF works: using your upper body to effectively 'press' the pedal into your foot, producing additional torque. A rather simple physics, actually, no tricky biomechanics about it.

I think your analysis is mistaken, but I can't think of an easy way to demonstrate why. Suffice it to say that I've heard far too many claims like this one which seemed superficially plausible, but when tested scientifically proved to have no merit. Testing this bar pulling theory should be an easy task; all it requires is a power meter. Why then hasn't anyone done it?

 

[Balor]

Erm, no. It is much harder than that.

Ok, someone will give you strava link and say: Well, I've been swinging the bars and outout 10 more watts (but got 3 more bpm HR).
Will you be actually satisfied? Rider in question might simply be pushing the pedals harder!

Switch between short and long bars? I think Larry already done that for aerodynamics and did note that it limits his upper reaches of power, but whether due to being unable to pull/swing the boom effectively or so not to swerve too much due to pedal feedback - again, not really clear.

Jim posted an article about producing torque this way, with power meter data actually, but I recall you were not satisfied as well. What WILL satisfy you? Can you come up with a comprehensive test procedure someone will actually be able to follow and consider the results conclusive proof of either existence or nonexistence of this phenomena?

 

[trplay]

What better way than a smart trainer? Same bike, drivetrain, rider. No wind or environment to worry about. Just read the wattage with and without.

 

[Osiris]

Erm, no. It is much harder than that.

Ok, someone will give you strava link and say: Well, I've been swinging the bars and outout 10 more watts (but got 3 more bpm HR).
Will you be actually satisfied? Rider in question might simply be pushing the pedals harder!

Switch between short and long bars? I think Larry already done that for aerodynamics and did note that it limits his upper reaches of power, but whether due to being unable to pull/swing the boom effectively or so not to swerve too much due to pedal feedback - again, not really clear.

Jim posted an article about producing torque this way, with power meter data actually, but I recall you were not satisfied as well. What WILL satisfy you? Can you come up with a comprehensive test procedure someone will actually be able to follow and consider the results conclusive proof of either existence or nonexistence of this phenomena?

Well, for starters I didn't say that power data considered in the abstract would prove the case. One could always raise the sorts of objections you mentioned, which is why credible test results should be consistent, repeatable, and verifiable. A skilled Cruzbike rider would be able to do this. I tried to do it and failed, but that may be because I haven't yet acquired the amount of control needed to execute the technique without the bike wandering off course repeatedly. Or perhaps I was doing it correctly, but noticed no power increase because the technique doesn't really work. It doesn't need to remain a mystery, because we have a large pool of test riders here to work with. Anyone here claiming to have benefited from this bar pulling technique already has the requisite skills to perform the experiment. That would go a long way toward settling the issue, right? Why rely on unsupported claims? As for Jim's article, are you referring to a test someone performed in a garage with weights hanging on the end of a string? That's not even close to duplicating what happens when riding.

 

[Osiris]

What better way than a smart trainer? Same bike, drivetrain, rider. No wind or environment to worry about. Just read the wattage with and without.

Now that's exactly the setup I suggested when the subject first came up on another forum: a trainer set on a moving platform so that the front end can pivot from side to side. I don't see any videos from "trplay1" showing the test being performed, though.

 

[Balor]

Well, for starters I didn't say that power data considered in the abstract would prove the case. One could always raise the sorts of objections you mentioned, which is why credible test results should be consistent, repeatable, and verifiable. A skilled Cruzbike rider would be able to do this. I tried to do it and failed, but that may be because I haven't yet acquired the amount of control needed to execute the technique without the bike wandering off course repeatedly. Or perhaps I was doing it correctly, but noticed no power increase because the technique doesn't really work.

Wait... you now have an MBB bent or you've been trying swinging the bars on a fixed boom bike?!

 

[Osiris]

Wait... you now have an MBB bent or you've been trying swinging the bars on a fixed boom bike?!

We're talking about swinging the bars on a Cruzbike. I have a V20, along with two fixed boom bents.

 

[Balor]

We're talking about swinging the bars on a Cruzbike. I have a V20, along with two fixed boom bents.

Oh, I see now. Well, what do you exactly have problem with - bar pulling or boom swinging?
Like I said, whether bar pulling will work for you is likely highly personal issue, and this is not merely moving the goalposts - that's just how it is. My N=1 example shows it rather unambiguously FOR ME, but I'm far from an ordinary cyclist (decent power yet clinically obese, for now at least).

Boom swinging, however, MUST work, but I'm simply unsure on extent of this effect, especially on Cruzbike with long boom and short tiller.
Come to think of it, my 90deg MBB with short boom and long tiller is much closer to DF in that respect (just analyse the 'center of rotation' when it comes to 'bike rocking' vs 'boom swinging') - it give your arms much more leverage, especially given that you are, indeed, severely limited in degree of boom swinging compared to DF bike

Admittedly, none of my MBB bikes were particularly stiff in handlebar deparment and that is bound to affect matters, maybe my updated front triangle will allow better 'upper body power delivery' this way?
Like I said, I do *find* myself boom swinging just like I sometimes find myself 'bike rocking' on DF, and this is a certain indication that your subconscious homed on some pattern it deemed effective and you would be wise to listen to such signals - it has MUCH more data and processing power than *you*, as a conscious person (a mere evolutionary afterthought, to be blunt), have. Yea, it rubs me the wrong way to rely on such 'black boxes', but at least it feels good and gives me some upper body exercise I sorely need. And I ride to feel good .

 

[ed72]

What better way than a smart trainer? Same bike, drivetrain, rider. No wind or environment to worry about. Just read the wattage with and without.

That would work for me but I think the extra power is quite obvious. The control run should be with hands on the bars and no pulling, just resting.....assume this would work on the trainer. Anything from 2-3 minutes really hard efforts..???

Power on the road would be less convincing unless done on a relatively slow hill (steep) and/or absolutely calm day because the side to side motion could very easily detach airflow over the rim skewing the data (condition dependent).

Strava data is almost useless without a lot of context and many replicates over time, for example.

I put a 2-Spoke wheel from the Netherlands onto my front today. I did some comparisons to the alleged dog front wheel (Flo 60 carbon) and it looks faster but the results would appear not terribly inspiring. Jury is out.

I also did my 10 mile TT and was 2 seconds slower than my best time (20:41 vs 20:43)with the Flo 60 despite making a little more power. So, the Flo is faster.....except, Rho was 1.21 today vs 1.165 on my PB day (66F vs 84 F). Oh, I also was in normal kit today vs skinsuit. And the pavement was slightly wet today with leaves and other debris here and there. The rear wheel was a GP4ksii vs Vittoria Speed on PB day. Oops, the Powertap with the GP4Ks11 reads 3% hi while the Vittoria Speed Powertap hub reads 1% low. Oh, I actually made less power today than on PB day. Side by side comparisons between the Flo and 2-Spoke today suggest otherwise. I am pretty confident which wheel is faster (making corrections for differences) but how much? The Strava reporters who say, I usually Huff, Puff, and Huff but only Huff and Puff now and my HR is now xyz......completely useless.

 

[ed72]

The process is not instantaneous though. Plus, lactate, given enough available oxygen can be consumed directly by other muscles, right - when they are taxed, but not too much. (And by heart muscles, a great deal, actually)
Burrows himself made this claim in one of his videos as to why upper body recruitment on DF can be actually beneficial.
You need to get it (and CO2) from working muscles though, and oxygen in, and when your blood flow is impaired 'downstream' (actually, ehehe, upstream in case of high BB) it does not matter much how effectively your lungs are working...

Your sprint power (as in - onset of severe blood acidation from lactate) may very well depend on ability of your WHOLE BODY to remove excess lactate from blood, but that is indeed 'my understanding' that is limited to a few research papers and Wikipedia articles.

What does the hypothalamus monitor to control heart rate?

CO2.

If perfusion is inhibited due to supine position and/or constraint of the overall inspiration due to seat position or even just tightening the abs, insufficient oxygen will be delivered and your functional threshold will be artificially lower than. I do not believe blood flow is impaired with feet above BB although possible. I am convinced bent legs is really a bent lung issue.

 

[Osiris]

Oh, I see now. Well, what do you exactly have problem with - bar pulling or boom swinging?

We're talking about the alleged power increase resulting from swinging the boom from side to side.

Like I said, whether bar pulling will work for you is likely highly personal issue...

I'm not sure what you mean by "bar pulling". What are you describing?

Boom swinging, however, MUST work, but I'm simply unsure on extent of this effect, especially on Cruzbike with long boom and short tiller.

I'm far from convinced that it must work. Consider the example of someone trying to lift a heavy barbell off the floor with his legs. He grabs the bar and pulls, but the weight is too heavy for his legs to lift it. Someone then suggests, "Why not pull up with your arms, thereby adding the power of your arms to the power of your legs?" You can easily see why this suggestion makes no sense. The leg muscles are already working at full capacity, and there is no way to add power to them with your arms. Similarly, if you're pedaling as hard as your legs are able to, nothing you do with your upper body will add power to your leg muscles. It would be an entirely different situation if you had two sets of pedals, one set for your arms, and the other for your legs; then you could pedal with your arms to increase the total amount of power your legs alone are capable of producing. But that isn't possible on a Cruzbike.

 

[Balor]

I'm not sure what you mean by "bar pulling". What are you describing?

Bar pulling (BOTH handlebars) is simply an alternative method to brace for power delivery instead of pushing against the seat.

I am convinced bent legs is really a bent lung issue.

You might have a good point - pushing into the seat with related muscle contraction might well limit your lung capacity and perfusion... at least, ehehe, for YOU. Like I said, I never even breathed hard when I switched to bents at first - I simply felt like I contracted some wasting sickness and my legs simply refused to pedal as they should! Only much later I became more taxed when it comes to breathing.
If 'bent lungs' was the only theory to explain bent adaptation, it would be the other way around - I'd be constantly gasping for breath like someone breathing into a plastic bag at first and only later it would get easier. It totally might be true for some positions, but my brief tests suggest that this is just not so for me.
Plus, it does not explain why power is so much more limited in anaerobic, not aerobic spectrum or the mystifying 'cannot into high cadence' issue. Or why "scraping" seems to work much better on a bent - even for an initial sceptic like Osiris.

I'm far from convinced that it must work. Consider the example of someone trying to lift a heavy barbell off the floor with his legs. He grabs the bar and pulls, but the weight is too heavy for his legs to lift it. Someone then suggests, "Why not pull up with your arms, thereby adding the power of your arms to the power of your legs?" You can easily see why this suggestion makes no sense.

Work is force times displacement.

When you simply pull on the bars, or swing them on RWD, you are not displacing your pedals relative to your pedal stroke.
When you swing the boom, you DO. If you fix your leg (say, right leg) and swing the bars to the LEFT (so boom swings to the right as well), the pedal will rotate slightly *against* your leg, try it. (Having wide Q-factor helps as well)
Voila, you did some work with your upper body that goes into propulsion without producing any WORK with your legs.

How much does it contribute to your total power is a question that I am not equipped to answer, except 'likely not much'.

 

[Osiris]

When you simply pull on the bars, or swing them on RWD, you are not displacing your pedals relative to your pedal stroke.
When you swing the boom, you DO. If you fix your leg (say, right leg) and swing the bars to the LEFT (so boom swings to the right as well), the pedal will rotate slightly *against* your leg, try it. (Having wide Q-factor helps as well)
Voila, you did some work with your upper body that goes into propulsion without producing any WORK with your legs.

How much does it contribute to your total power is a question that I am not equipped to answer, except 'likely not much'.

This analysis appears to me to be completely mistaken. When you push the pedal away from you (during the power phase of the pedal stroke) your leg muscles are placing a certain amount of load on the pedal. If you simultaneously pull the pedal toward you by swinging the boom, you are INCREASING that load. By increasing the resistance your leg must overcome during each pedal stroke, you are necessarily increasing the work your legs must do.

I think the mistake many people have made is to think of these two operations as if they work in isolation. It seems plausible that if pushing on the pedal places, say 50 lbs of pressure on the pedal, and that pulling the pedal toward you against resistance by swinging the handlebar produces say, 10 lbs of pressure, then you have just increased the total force applied during each pedal stroke from 50 to 60 lbs. But this is no different than pushing 10 lbs harder against the pedal with your foot. You haven't added any power by swinging the handlebar. And if your legs are already pushing as hard as they can against the pedals, then increasing the load they have to fight against will only slow down your cadence while adding no power.

 

[ed72]

Pedaling is not a simple push/pull. There are many levers and muscles that work in concert and that work counteracting forces in pairs. Pedaling involves both translational and rotational forces. Stomping as hard as you can and forcing your back into the seat MERELY provides the maximum translational component of force. Each muscle has a certain load or torque that is optimum and also a maximum.

If you think the upper body can not contribute to the overall power to the wheels, hop onto a Concept 2 rower and try to make the power with just your legs. Upright riders certainly use the upper body for power.......look at the slow motion sprint at 19 seconds

 

[Balor]

You haven't added any power by swinging the handlebar. And if your legs are already pushing as hard as they can against the pedals, then increasing the load they have to fight against will only slow down your cadence while adding no power.

Adding to what Ed said above, what we have in 'boom swinging' not unlike oval chainrings... which you don't believe in too, right .
But Ed tried Rotors and got pretty astounding results if you ask me. I actually have a set as well myself, but I cannot fit them to my bent... I'll need to test them objectively to see whether they work for me with power meter (at least on a trainer) and maybe have them shortened which is no small feat because they are heavily CNCed.

Remember, that unlike with a linear drive, using pedals results in a continuously variable leverage ratio where in some points extra pressure is extremely advantageous, and in others - completely useless, and speed/force of your muscle contraction is complex function with certain optimums + there is muscle synergies to consider! And again, this is not motivated reasoning - we are trying to explain data we seem to have (like in case on Ed and rotor cranks - I presume that Rotor cranks is not an investment significant enough to go to such length to justify it), not trying to arrive to a favourable conclusion, and conclusion is 'seems plausible, more research is needed'.

Personally, marketing 'boom swinging' in particular as something that can grand you huge, DF-like spring powers may be a bit misleading, but I don't think Cruzbike go as far. In fact, as you well know, real sprinting power comes from fast twitch muscle requirement at high cadence, and track spinters generate their nearly 4 HP of watts while sitting and spinning huge cadences - and not just because their bikes are geared pretty low and rocking the bike with, like, 300 Hz is likely impossible, but it certainly *feels* *somewhat* advantageous. Untill we have a real model of what is going on (with clearly defined causes and effects) I'm trying to keep an open mind.

P.S. 'Road bike geometry' *is* pure marketing, and here I indeed have models and concrete proof in terms of prototypes, but admittedly 'looking good and familiar' on an ad might help them sell more bikes that geometry that works better in practice but looks weird... Plus, like I said on other forums, if your bike is sufficiently controlled in all conditions for you, improving on it is useless and may compromise other aspects (even if those aspects are "just" aesthetics). What I'm a bit peeved at is that models that are not intended for high performance and geared for 'accessibility' in general can massively benefit from much steeper steering angles and would not appeal to 'dyed in the wool DF racer' anyway, so bending over backwards in that area is useless anyway.

 

[bladderhead]

We all know that DF bikes are uncomfortable, but bending over backwards sounds even worse. Balor's designs are getting really weird now.

 

[Osiris]

Adding to what Ed said above, what we have in 'boom swinging' not unlike oval chainrings... which you don't believe in too, right .

Right. We were talking specifically about Q-rings, by the way, not oval chain rings in general. Ed himself stated that he didn't see any performance benefit from Q-rings, and finally sold his:

"I did not measure any benefit with Q-Rings and sold them. Zippo. I did get a slight benefit with QXL with tweaking of the settings."

But Ed tried Rotors and got pretty astounding results if you ask me.

That's not what he claimed in the quote above. But again, the "slight benefit" Ed obtained was from Rotor QXL cranks, not from Q-rings, so we don't have a disagreement here.

Personally, marketing 'boom swinging' in particular as something that can grand you huge, DF-like spring powers may be a bit misleading, but I don't think Cruzbike go as far. In fact, as you well know, real sprinting power comes from fast twitch muscle requirement at high cadence, and track spinters generate their nearly 4 HP of watts while sitting and spinning huge cadences - and not just because their bikes are geared pretty low and rocking the bike with, like, 300 Hz is likely impossible, but it certainly *feels* *somewhat* advantageous. Untill we have a real model of what is going on (with clearly defined causes and effects) I'm trying to keep an open mind.

Absolutely. In fact, I'm in a generous mood, so I don't even require an explanatory model. If someone can demonstrate that swinging the bars on a Cruzbike actually produces more power than can be produced with the legs alone, I'll become a believer. But I haven't seen any demonstration. All I've seen are unsupported claims and rather dubious hypotheses for how this is supposed to work. I've explained to you why I think it makes no sense to believe that you can add power to your legs by swinging the handlebar. Neither you nor Ed have shown me where my analysis goes wrong. What you are both doing instead is engaging in rhetorical hand waving, and making comparisons to road bikes and rowing machines, the mechanics of which are completely different than what we're discussing. Ed thinks that swinging the bars can result in a 15-20% power increase. That's enormous, and should be instantly noticeable on a power meter. You think the power increase is far less than that. I wouldn't be at all surprised if it's zero. The only way to determine which it is, is to perform tests whose results are consistent and repeatable. The video someone posted above illustrates one way in which this might be accomplished, but unfortunately no such test has yet been performed.