ratz
Wielder of the Rubber Mallet
Wait your Australian?Probably the wisest words ever written.
Road bike vs. recumbent comparison
- Thread starter Osiris
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Osiris
Zen MBB Master
No. What I said (several times) was that testing the push pull technique at power levels well below maximum is not going to produce useful results because it's impossible to determine whether the power being produced is attributable to upper body muscles working in combination with the legs, or whether the power is being produced by the legs alone. I then went on to say that a method to sidestep this problem would be to test duration at the same power output, and from that determine whether wagging the handlebars actually works as advertised. You seemed to understand this, judging by your response, so why are you now attributing statements to me which I never made?
Before I purchased my first bent, I dare guess that I read every meaningful thread on BROL related to bent climbing in general and CruzBikes in particular. All of them. The question at hand has been litigated over many hundreds of pages over there. I believe the S30 V2 is probably the best short hill (under a mile), steep (8-12%) climbing bent out there followed by the V20. How many experienced Cruz owners claim that their bike doesn't climb? How many records have been smashed on a Cruz? Is there much to add?
QED.
For anyone who thinks the upper body plays no power producing role in climbing, watch these two videos and make the same statement. At least listen at 1:00 on the first video. Watch the elbow movement towards the obliques, especially Pantani. This is relevant because this motion is what can be replicated on a Cruz. To me....it is obvious. Has anyone considered why cross country skiers or rowers have higher VO2 max than cyclists or swimmers, but this goes against the more limited assertion of faster 1 km climbs.
One needs to look back to circa 2010 when Jim proposed a "pharm-like protocol" with 20 Cruz vs 20 rear drive bents. The important point everyone misses? Jim was talking about a 1 km climb or about 3-5 minutes in duration for the average fit rider. This is a VO2 max effort, not a 5-20 second sprint and not a 40 km TT. These 3-5 minute efforts determine breakaways in racing and they often determine win or loss. They also very much determine overall time to distance on recreational rides in rolling terrain. The one BROL thread in particular devolved into idiosyncratic design of experiment particulars but in my opinion based upon many decades of bicycle riding and racing and having literally reviewed and approved many hundreds if not thousands of real scientific protocols and study reports, an advantage of 4-5% can be easily determined with statistical confidence with a much smaller sample size with riders acclimated to the techniques of both. A "real" scientific study is cost prohibitive but it is also unnecessary. Why a 5 minute hill? There is no truer test, is easy to control, and easy to execute many replicates (confidence intervals).
One would merely need a few competent recumbent riders to ride a V20 vs say a Carbent, CA3 or M5. The powertap wheels should be swapped to control.
Sugarloaf "mountain" north of Altoid Springs Florida would be the perfect venue if competent bent rider(s) were nearby. The kind who know not to start up in a 53x13 lest they fall over or to shift to the small ring on a slow 90 degree corner or who do not fall off all the time. One who doesn't pedal MBB with waggling arms 180 degrees out of phase.
Personally, I would do several days of testing. ABBA, BAAB, etc. Four hard efforts is about the limit for most riders. The following hypothetical set of results would show a statistical significance to my satisfaction. To those who would argue that the 4% V20 advantage is due to chain losses, I doubt the loses are more than 1% but it would be easy to measure. A very carefully calibrated PT and pedal PM would be required but most PMs vary by at least +/- 1%. This is why I would swap PT wheels from the V20 to the RWD bent to control this error. The best current "data" is from an rider who compares strava segments from one day to the next, which is worthless.
run these into your favorite stats package.
RWD bent: 300, 301, 305, 299, 302, 297, 295, 298 watts
V20: 310, 312, 315, 320, 309, 312, 315, 310 watts
I would predict much larger differences in power going to the V20, myself.
Nobody is going to do these studies. On the other hand, it seems that 99.9% don't need to.
QED.
For anyone who thinks the upper body plays no power producing role in climbing, watch these two videos and make the same statement. At least listen at 1:00 on the first video. Watch the elbow movement towards the obliques, especially Pantani. This is relevant because this motion is what can be replicated on a Cruz. To me....it is obvious. Has anyone considered why cross country skiers or rowers have higher VO2 max than cyclists or swimmers, but this goes against the more limited assertion of faster 1 km climbs.
One needs to look back to circa 2010 when Jim proposed a "pharm-like protocol" with 20 Cruz vs 20 rear drive bents. The important point everyone misses? Jim was talking about a 1 km climb or about 3-5 minutes in duration for the average fit rider. This is a VO2 max effort, not a 5-20 second sprint and not a 40 km TT. These 3-5 minute efforts determine breakaways in racing and they often determine win or loss. They also very much determine overall time to distance on recreational rides in rolling terrain. The one BROL thread in particular devolved into idiosyncratic design of experiment particulars but in my opinion based upon many decades of bicycle riding and racing and having literally reviewed and approved many hundreds if not thousands of real scientific protocols and study reports, an advantage of 4-5% can be easily determined with statistical confidence with a much smaller sample size with riders acclimated to the techniques of both. A "real" scientific study is cost prohibitive but it is also unnecessary. Why a 5 minute hill? There is no truer test, is easy to control, and easy to execute many replicates (confidence intervals).
One would merely need a few competent recumbent riders to ride a V20 vs say a Carbent, CA3 or M5. The powertap wheels should be swapped to control.
Sugarloaf "mountain" north of Altoid Springs Florida would be the perfect venue if competent bent rider(s) were nearby. The kind who know not to start up in a 53x13 lest they fall over or to shift to the small ring on a slow 90 degree corner or who do not fall off all the time. One who doesn't pedal MBB with waggling arms 180 degrees out of phase.
Personally, I would do several days of testing. ABBA, BAAB, etc. Four hard efforts is about the limit for most riders. The following hypothetical set of results would show a statistical significance to my satisfaction. To those who would argue that the 4% V20 advantage is due to chain losses, I doubt the loses are more than 1% but it would be easy to measure. A very carefully calibrated PT and pedal PM would be required but most PMs vary by at least +/- 1%. This is why I would swap PT wheels from the V20 to the RWD bent to control this error. The best current "data" is from an rider who compares strava segments from one day to the next, which is worthless.
run these into your favorite stats package.
RWD bent: 300, 301, 305, 299, 302, 297, 295, 298 watts
V20: 310, 312, 315, 320, 309, 312, 315, 310 watts
I would predict much larger differences in power going to the V20, myself.
Nobody is going to do these studies. On the other hand, it seems that 99.9% don't need to.
Osiris
Zen MBB Master
super slim
Zen MBB Master
You mean LATE 2019, as you are not in a Liberal marginal seat!
jond
Zen MBB Master
Lol Politics religion America and green skinned Egyptians are for other forums my fellow socialist.
jond
Zen MBB Master
Australian wisdom is not a misnomer.
No longer does it end on the footpath outside the pub. Exhibit one . our very own Slim.
Balor
Zen MBB Master
I know that was in jest. My comment *still* stands, though... even if coming from somewhat whos some personality traits are well outside of pathological norms (and I emphatically not claiming that your are, just... a bit overemphasized
).I've just been there (and read some literature on the subject) and bashing people with rational arguments from a position of 'intellectual superiority' works extremely poorly, even when they are 100% clear and transparent, and even less so (impossible, in fact) when issue at hand is murky. Rationality is a skill that not intuitive and even rather painful to acquire (Yudkowsky's HPMOR illustrated that rather wonderfully if you ask me).
If you don't want to just waste yours (and everyone else's) time, a bit different approach is required.
Balor
Zen MBB Master
Depends on whether those are power or return idlers, and admittedly Marco Ruga test was a bit flawed and cannot account for difference between transmission losses and frame losses.
Osiris
Zen MBB Master
100% don't need to. 99.9% are perfectly happy believing what they want to believe.
I'm willing to participate in such a test, but there is the practical problem of finding enough bent riders. After Blake Murray's crash, I may be the only Cruzbike rider left in this area. There are a handful of Bacchetta riders, but judging by their appearance, only one of them is likely to survive the ride up Sugarloaf.
I just had another look at the Sugarloaf segment on Strava. If your test requires a 5 min climb, this isn't the hill for it. The bottom and top of Sugarloaf are almost flat. The only portion one would have to climb measures 0.41 miles. Phil Gaimon holds the record on it. Maybe if I get the hang of this bar waggling technique, I'll be able to take the KOM from him.
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Balor
Zen MBB Master
By the way, I've installed a very 'cruzlike' cockpit on my bent, more like one of Marco Ruga actually but with drops sawed off because they inferfere with my thighs, going from about 550m width to 400.
I've *instantly* noticed that:
a. Pulling for power is much easier.
b. Boom swinging is MUCH harder and I now get no subconscious incentive to do it!
(And by going 'Larry Oslund' - grabbing the bars near the stem I think I gain about 2kmh cruising speed)
I did not test extencively, but I suspect that your ability to do 'bar swinging' greatly depends on your upper body strength and leverage provided by bars.
I've *instantly* noticed that:
a. Pulling for power is much easier.
b. Boom swinging is MUCH harder and I now get no subconscious incentive to do it!
(And by going 'Larry Oslund' - grabbing the bars near the stem I think I gain about 2kmh cruising speed)
I did not test extencively, but I suspect that your ability to do 'bar swinging' greatly depends on your upper body strength and leverage provided by bars.
DavidCH
In thought; expanding the paradigm of traversity
Redefining the gold standard. The university of Colorado has an independent power meter calibration tool that could prove once and for all about this topic of going up hill on an MBB. If you watch the video you can see the bikes being tested on an incline. I think it's possible that their system can be applied to a recumbent as well.
Take a look at the video... It's interesting
Take a look at the video... It's interesting
His results showed to me that the V20 or MBB design could climb as well as a DF but the differences between the DF and bent in his tests were within the noise of the power meter. There was a very good study recently showing the accuracy and precision of all the top power meters. SRM and Powertap came out on top with a little over +/-2%. I know one of my PT reads 1% low and the other 3% high. The crank based meters are the worst. So, comparing the power at the crank to the powertap hub measurement wouldn't be terribly conclusive. I still struggle with the accepted notion that more chain tension results in lower power loss and think that this original study in 1999 ish conflated big-big and small-small with chain tension.
Balor
Zen MBB Master
I thought that was a very common notion? I've seen it mentioned many times in different sources... note that more chain tension results in less RELATIVE power loss. Basically, you still lose more at high power, just not as much as you should if it was linear.
http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
If the losses are at the pin/bushing interface as described in the linked article, I fail to understand how more force on those points results in lower losses. Something I have always done wrong, I guess.
Balor
Zen MBB Master
Have a look:
http://sci-hub.tw/10.1243/0954406021525179
http://sci-hub.tw/10.1243/0954406021525179
Thank you!!!
When I look down at the chain on a upright while riding, it does not move around much whereas on my RWD bent, there is all manner of vibration, noise, and overall "jiggly" movement. The tension spring on 1X rear derailleur put the chain under a lot more tension, I wonder if this would cut down the vibration in the chain that I observed.
The reason I am even more careful about chain maintenance and you are free to call me crazy like someone somewhere said but I did a 20 minute FTP test and a few days later thoroughly cleaned my seemingly 20 foot long chain with multiple ultrasonic and then multiple solvent sessions followed by a heated application of Squirt. It really was not "dirty" or unlubricated. I went out and did a 10 mile TT in 20ish minutes. My rear powertap hub recorded something like 15 more watts and of course, I had a PB TT. My performance does not improve ever by so much in 5 days and in fact my legs were sore, so the losses were probably between the crank and hub (chain) or at least some of it. I came to the conclusion that the rwd bent chain is much more susceptible to losses if the chain is not perfectly maintained and the article you linked suggests that I was right.
I am not sure what the solution might be. I am running the stock pulley. Any thoughts other than buy a MBB FWD bent?
Balor
Zen MBB Master
It is not just return chain. I've noticed chain 'bouncing' up and down on power-side at dead spots as well, sagging under it's own weight. Cannot be good.
FWD-TC, like one of Performers? An order of magnitude less steering torque and steering inertia to contend with compared to FWD-MBB.
Horizontal chain run is short, and there is no 'trail-like' friction force even if you get some fork misalignment under torque, I presume. Can also have some passive suspension with flexible rear chainstays this way as well.
Or order this bad boy and stomp recumbent PBP record into dust:
Pikuponcho No torq FWD Piet Kunis
FWD-TC, like one of Performers? An order of magnitude less steering torque and steering inertia to contend with compared to FWD-MBB.
Horizontal chain run is short, and there is no 'trail-like' friction force even if you get some fork misalignment under torque, I presume. Can also have some passive suspension with flexible rear chainstays this way as well.
Or order this bad boy and stomp recumbent PBP record into dust:
Pikuponcho No torq FWD Piet Kunis
I'm thinking of trying a larger t-cycle pulley with 23 teeth for the power side. This should add tension and give more contact points to the chain and have the contract to the rollers instead of the plates. I am not sure about the return side (my chain is dropped). I am not sure how to measure the effectiveness short of designing a fixture and motor test bed. My power profile is well established within "XERT" and a tax rebate of 3-4% power would show-up as a breakthru in the software.....3-4% increases in a short period of time are unusual for a fit rider.
This 8% power difference between the V20 and stick bike has me, even if the measurement was at low power and it did not scale linearly. (I suspect it is 8W loss at 100W and maybe 10W loss at 300W or something like that). Maybe this one key factor in the observed climbing ability of a Cruz bike
This 8% power difference between the V20 and stick bike has me, even if the measurement was at low power and it did not scale linearly. (I suspect it is 8W loss at 100W and maybe 10W loss at 300W or something like that). Maybe this one key factor in the observed climbing ability of a Cruz bike
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