[HAMR] Current thoughts on the record attempt?

[Kim]

I don't know enough about this particular aspect to make a sensible comment.

Me neither, but received wisdom seems to be that the recumbent position is less conducive to cardiovascular performance, which limits your power compared to an upright (even though you may go faster due to aerodynamics).

I do know several folk who have transitioned from recumbents back to uprights for long brevets. If you only have a single (recumbent) riding position, you can't afford the slightest discomfort in that position.

Indeed.  I'd say that even if it's perfect ergonomically, keeping your body in exactly the same position for hours on end becomes uncomfortable.  When audax-style riding on a bent, I take the time to stop, stand up and stretch once an hour or so when there isn't a specific reason to stop.  That sort of thing adds up, but probably less than the aero advantage (or the harder to quantify different-shaped-bike advantage).

[Kim]

Out of interest, how many of the naysayers have actually used recumbents?

(Not that I can comment; while I'm an experienced touring 'bent rider, I've never done more than a test ride on the sort of speed-oriented machine that we're discussing here.  Same goes for wedgies, for that matter.)

[simonp]

Out of interest, how many of the naysayers have actually used recumbents?

I have. I found it harder on my quads and knees. It's harder to pedal in circles on a recumbent, I think.

Clearly it's worked for Kurt. There are other tradeoffs such as hand comfort, neck issues etc.

[LMT]

Most unfaired recumbents aren't hugely faster than a good TT bike anyway.

Kurt regularly uses a highracer. Steve used a trike with the broken leg.

Yes they are, 180w will give a difference of about 3mph. And contrary to popular belief on a like for like basis they go up hills quicker as well. Only on a hill more than 8% will the upright bike make ground back - providing of course the upright bike is lighter.
 

[LittleWheelsandBig]

I must be using out-of-date recollections. Others know more about this than me.

[Kim]

Out of interest, how many of the naysayers have actually used recumbents?

I have. I found it harder on my quads and knees. It's harder to pedal in circles on a recumbent, I think.

Quads certainly, but muscles adapt.  Knees depends on how you use the seat and gears.  Disagree about pedalling in circles.

Which raises the other important point - some people's preferred riding style is better suited to 'bents than others (which explains a lot of the marmite factor once you get past the basics, I think).  Not the sort of thing you want to work out during a record attempt.  (I don't count the one-legged triking, as that was performance limited by injury.)

Basically, I think a highracer is an excellent tool to have in the arsenal from the outset, but not something you can drop-in and reliably expect huge gains from.

[LMT]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Tests have shown that over 8%, the speed is to slow to take advantage of the aero advantage that riding a recumbent brings. But of course you make this up on the flats and going down hills.

With respect to Steve's attempt if he was to invest in a low racer or a M5 carbon high racer then headwinds would have a lesser bearing on his routing.

[Von Broad]

Kurt has no problem powering a DF for days on end, that's where he's done the majority of his riding - we've all seen it on the Facebook videos. Are there stats that show how he's divided his time between the bikes?

I'd be interested to see what he has to say about his experiences of the DS, because from a distance it looks like he's used the bent almost like a recovery style of bike. I'm not aware of him piling on a huge advantage when he rides the recumbent, you've really got to be in the zone and fully accustomed to get the most out of them really, but he's clearly had a reason to have the Bacchetta in the fleet. Like I said, it's probably been for variety as much as anything.

[Kim]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Quite.

OOI, do you find your maximum power limited by the biomechanics?


My anecdata (no power meter, sadly) is that at 'audax pace' all bikes climb equally well (assuming equivalent weight, gearing and a non-trivial gradient).  But if I go to flat out puke-your-guts-out sprint mode, uprights get me to the asthma attack faster.


Anyway, we're going off-topic...

[Kim]

I'd be interested to see what he has to say about his experiences of the DS, because from a distance it looks like he's used the bent almost like a recovery style of bike. I'm not aware of him piling on a huge advantage when he rides the recumbent, you've really got to be in the zone and fully accustomed to get the most out of them really, but he's clearly had a reason to have the Bacchetta in the fleet. Like I said, it's probably been for variety as much as anything.

Seems like a sensible reason to me; stops hand/arm/neck/saddle problems eating into mileage.  Interestingly, Steve doesn't seem to have had many of those.

[LittleWheelsandBig]

Steve has had enough adaption over the years to be more comfortable sitting on a bike than sitting on a couch. The Tour de France racers between the wars reputedly were similarly adapted.

[LMT]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Quite.

OOI, do you find your maximum power limited by the biomechanics?


My anecdata (no power meter, sadly) is that at 'audax pace' all bikes climb equally well (assuming equivalent weight, gearing and a non-trivial gradient).  But if I go to flat out puke-your-guts-out sprint mode, uprights get me to the asthma attack faster.


Anyway, we're going off-topic...

We are going off topic, but it's one of interest especially to the DF riders out there who somehow think they are faster going up a hill.

In answer to your question, my max power is not limited by bio mechanics, because I ride a FWD-MBB system and can grip the bar and deliver power much in the same way as a sprinter hunched over the bars (using thier arms and lats) yanking on the bar as they sprint for the line.

Power data shows that peak power on the bent is 1258w and on the upright 1058w. However I've only done this test once on each platform out on the road for fun, it's not really something that I look to test purely because I'll never look to sprint up a hill - certainly not giving a max effort anyway.   

[Karla]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Tests have shown that over 8%, the speed is to slow to take advantage of the aero advantage that riding a recumbent brings. But of course you make this up on the flats and going down hills.

With respect to Steve's attempt if he was to invest in a low racer or a M5 carbon high racer then headwinds would have a lesser bearing on his routing.

You forgot the one about f = mg.  If a recumbent is heavier, it will go up hills slower. 

The 8% figure is spurious: the power lost to gravity and aero drag both scale with speed, not gradient.  P_a scales with the cube of speed, P_g scales linearly, hence why aero drag is unimportant going up any serious hill - and unless you're Chris Froome and can go up steep hills at speeds fast enough for that V³ to come into effect, that's probably going to be a lot less than 8%.

[LMT]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Tests have shown that over 8%, the speed is to slow to take advantage of the aero advantage that riding a recumbent brings. But of course you make this up on the flats and going down hills.

With respect to Steve's attempt if he was to invest in a low racer or a M5 carbon high racer then headwinds would have a lesser bearing on his routing.

You forgot the one about f = mg.  If a recumbent is heavier, it will go up hills slower. 

The 8% figure is spurious: the power lost to gravity and aero drag both scale with speed, not gradient.  P_a scales with the cube of speed, P_g scales linearly, hence why aero drag is unimportant going up any serious hill - and unless you're Chris Froome and can go up steep hills at speeds fast enough for that V³ to come into effect, that's probably going to be a lot less than 8%.

The aero advantage for a bent is there upto a hill of about 8% grad. This has been tested many times, with papers published on it.

My own tests show that my recumbent with a power output of 350w goes up a hill with an average gradient of 6% 0.8kph quicker than my upright athe same power, and the recumbent is heavier by 2lbs.

[Kim]

You forgot the one about f = mg.  If a recumbent is heavier, it will go up hills slower.

Well obviously.  It's only reasonable to compare like for like, at least within the bounds achievable by practical engineering.  You can get some pretty light recumbents these days.

Similarly, you have to control for the rider (just using the same person isn't good enough, unless you measure power)


These are the usual reasons people think recumbents are slow at climbing; they're usually comparing heavy recumbents^[1] with lighter uprights, or they're comparing weaker recumbent riders (who can keep up a decent pace on the flat because aerodynamics) with stronger upright riders.


_{[1] The overwhelming majority of 'bents you come across in the wild are tourers.}

[Karla]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Tests have shown that over 8%, the speed is to slow to take advantage of the aero advantage that riding a recumbent brings. But of course you make this up on the flats and going down hills.

With respect to Steve's attempt if he was to invest in a low racer or a M5 carbon high racer then headwinds would have a lesser bearing on his routing.

You forgot the one about f = mg.  If a recumbent is heavier, it will go up hills slower. 

The 8% figure is spurious: the power lost to gravity and aero drag both scale with speed, not gradient.  P_a scales with the cube of speed, P_g scales linearly, hence why aero drag is unimportant going up any serious hill - and unless you're Chris Froome and can go up steep hills at speeds fast enough for that V³ to come into effect, that's probably going to be a lot less than 8%.

The aero advantage for a bent is there upto a hill of about 8% grad. This has been tested many times, with papers published on it.

My own tests show that my recumbent with a power output of 350w goes up a hill with an average gradient of 6% 0.8kph quicker than my upright athe same power, and the recumbent is heavier by 2lbs.

No.  Aerodynamic drag is a function of speed.  The speed you can go up an 8% hill, and thus the ratio of power lost to drag and gravity, will depend on the rider.  Variation between riders is enough that 8% is a meaningless figure. 

Also, LWaB was talking about "a good TT bike".  When you did your tests, were you using a good TT bike?  What were your CdA values for your recumbent and your upright?

[zigzag]

The aero advantage for a bent is there upto a hill of about 8% grad. This has been tested many times, with papers published on it.

i'd be interested to read at least a couple of these papers, as in my experience the real advantage of recumbent is going downhill. on a flat it's the same as riding an upright bike on tribars, and they are slower up the hills. it's probably an unfair comparison as my bikes were 7-8kg and recumbents at least 4kg heavier.
fwiw, i climb ~10% slower on a bike that's 5kg heavier.

[LMT]

You are missing the point I'm making, the speed that I go up a hill is such that the aero advantage outweighs any sort of disparity in weight between my recumbent and my upright. All the figures used are constants, - do the maths.

I've no idea what my Cda values are for my recumbent and upright, I've never worked them out. From what I've seen 180w gives me a 3mph advantage over my upright. A good TT bike would not be a whole lot better, and certainly would not be good for Steve's attempt imo given the such aggressive geometry when churing out such a large milage.

[LMT]

The aero advantage for a bent is there upto a hill of about 8% grad. This has been tested many times, with papers published on it.

i'd be interested to read at least a couple of these papers, as in my experience the real advantage of recumbent is going downhill. on a flat it's the same as riding an upright bike on tribars, and they are slower up the hills. it's probably an unfair comparison as my bikes were 7-8kg and recumbents at least 4kg heavier.
fwiw, i climb ~10% slower on a bike that's 5kg heavier.

All the need Zigzag is plug some figures into the equation that I posted a few posts ago, power, weight, drag it's all there.

An upright bike with tri bars will never be on par with a recumbent - certainly not one that is in the league of a M5 CHR, V20, an Encore or a Carbent.  TBH I'd piss over anyone on a tri bike.

[Greenbank]

Can the bike (recumbent vs upright) discussion please fuck off to another thread?

Ta.

[hillbilly]

I hope Steve doesn't use a recumbent.  I'd lose respect for him and his attempt.

News just in:  He already did.

On the restart? I know about the trike recumbent used whilst he nursed a broken ankle. And which I thought he packed away come August.  But I may be wrong.

[mattc]

I hope Steve doesn't use a recumbent.  I'd lose respect for him and his attempt.

News just in:  He already did.

On the restart? I know about the trike recumbent used whilst he nursed a broken ankle. And which I thought he packed away come August.  But I may be wrong.

Yes, that is my (unreliable) understanding too.

But if it turns out he only used the 1-legged* machine, I can say hand-on-heart that I would rate his Jan1st-Dec31st effort as more admirable than a proper mixed recumbent/DF attempt (as used by at least one rider on another continent).

Purely personal opinions, as there is no current official structure for such subtleties! This is the "Current THOUGHTS" thread


*I find it hard to believe that any 1-legged recumbent is as fast as a 2-legged upright.

[Arry-R]

On the restart? I know about the trike recumbent used whilst he nursed a broken ankle. And which I thought he packed away come August.  But I may be wrong.
[/quote]





I believe the Ice recumbent was returned to the company who had kindly lent it to Steve

[Frank9755]

Because the circuit would be quite short and the idea is ride in a fast group, headwinds are much less of a problem, as long as Steve doesn't do an upwind turn. That is the job of a big bloke who doesn't mind headwinds.

It would be great to find a circuit and get half a dozen or so of us riding round with him at weekends, doing the sheltering.  And  I agree that an off-road circuit would make that a lot more pleasant.  But, a lot of the time, Steve would inevitably be riding on his own, so wind would be a factor.  Then, a decent on-road time trial circuit would always be quicker.  The assistance you get from being passed by a steady stream of traffic is typically 1-2mph.

[Frank9755]

I'm quoting data from my own tests carried out my recumbent and upright with some P1 powertap pedals.

And regarding the hill thing, it's physics:-

F=CdA*p*(v^2/2)

Stands to reason that if the recumbent has a lower drag coefficient (CdA) then it requires less power to go up a hill at the same speed.

Tests have shown that over 8%, the speed is to slow to take advantage of the aero advantage that riding a recumbent brings. But of course you make this up on the flats and going down hills.

With respect to Steve's attempt if he was to invest in a low racer or a M5 carbon high racer then headwinds would have a lesser bearing on his routing.

You forgot the one about f = mg.  If a recumbent is heavier, it will go up hills slower. 

The 8% figure is spurious: the power lost to gravity and aero drag both scale with speed, not gradient.  P_a scales with the cube of speed, P_g scales linearly, hence why aero drag is unimportant going up any serious hill - and unless you're Chris Froome and can go up steep hills at speeds fast enough for that V³ to come into effect, that's probably going to be a lot less than 8%.

The aero advantage for a bent is there upto a hill of about 8% grad. This has been tested many times, with papers published on it.

My own tests show that my recumbent with a power output of 350w goes up a hill with an average gradient of 6% 0.8kph quicker than my upright athe same power, and the recumbent is heavier by 2lbs.

No.  Aerodynamic drag is a function of speed.  The speed you can go up an 8% hill, and thus the ratio of power lost to drag and gravity, will depend on the rider.  Variation between riders is enough that 8% is a meaningless figure. 

Also, LWaB was talking about "a good TT bike".  When you did your tests, were you using a good TT bike?  What were your CdA values for your recumbent and your upright?

But back to Steve - the comparison is not with a good TT bike with a fine-tuned aero position.  This suggests to me that Steve on a recumbent he was used to riding would not lose to Steve on the Sojourn on anything but the steepest climbs (which he shouldn't be doing in any case!).

Overall, an interesting discussion.  I'd conclude that Steve is clearly losing out by not having a recumbent in his armoury.  ISTR that he ruled it out on practical grounds (too long to adapt) rather than for ideological reasons.  But it should be something for serious consideration / preparation if there is a third attempt.  How long would a reasonable adaptation take? Say enought to allow him to use it for the odd half-day (when he was staying close to home)?