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Dreamer
recumbent guru

USA
541 Posts

Posted - 01/12/2012 : 17:55:53

Off the Road.cc website: Speed skating world champion turned Olympic cyclist Jan Bos to spearhead Dutch challenge

"Just a fortnight after Flying Scotsman Graeme Obree revealed plans to attempt to break the world human powered vehicle speed record, a competing bid has been launched by Dutch former speed skater Jan Bos � raising the prospect of a battle similar to that involving Obree and Chris Boardman, among others, for the Hour record during the 1990s.

Bos, best known as a speed skater � he won silver medals at the Winter Olympics in Nagano and Salt Lake City, and is a two-time world champion � is also an accomplished cyclist.

Together with his brother Theo, now riding for Rabobank, and Teun Mulder, Bos was part of the Dutch team sprint squad that finished sixth at the Athens Olympics in 2004."

The article appears with a picture of the Velox and team Delft. If the article is accurate, the selection of Bos as one of the riders for the Velox 2 could be a great combination.

Edited by - Dreamer on 01/12/2012 17:58:23

Adam C
recumbent enthusiast

USA
219 Posts

Posted - 01/12/2012 : 18:36:13

Can one of the Delft folks confirm this?

Tijn
Starting Member

Netherlands
1 Posts

Posted - 01/13/2012 : 02:36:44

Yes, we can confirm this.

Jan Bos and, again, Sebastiaan will be our riders for this year's WHPSC. http://tswi.org/english/bulletin/dutch-attempt-world-bicycle-speed-record

Tijn van Omme
Human Power Team Delft & Amsterdam

Edited by - Tijn on 01/14/2012 04:09:52

Jack
Starting Member

Netherlands
46 Posts

Posted - 01/13/2012 : 03:35:49

Because of the . it is a dead link, this is the correct working one.
http://tswi.org/english/bulletin/dutch-attempt-world-bicycle-speed-record
Of course, we keep this information secret so we write about it in a language that few people speak and nobody understands (I.e. dutch)
http://www.ligfiets.net/news/4034/hpt-team-delft.html

Upright Mike
human power expert

USA
3007 Posts

Posted - 01/13/2012 : 04:37:23

In 2009, Theo Bos was warming up at the Apeldoorn track while the Recumbent Record Weekend was happening on the track. Here is a picture from Gert-Jan of the 200-meter recumbent (Sean Costin) and 200-meter UCI record holders (Theo Bos). Maybe he mentioned something to his brother, like "hey, these "older" guys on recumbents are almost as fast as me! Maybe we should try those recumbents if we want to go faster!"

Larry Lem
human power supergeek

South Sandwich Islands
1971 Posts

Posted - 01/13/2012 : 06:38:45

Golly. He appears to a foot taller than Sean. At 7 feet, he'd tower over little-bitty Thomas and JM.

I wonder how tall Jan Boss is?

(edited 1/17 to not create confusion over who will be racing at Battle Mountain)

Larry Lem

Edited by - Larry Lem on 01/17/2012 08:27:30

Upright Mike
human power expert

USA
3007 Posts

Posted - 01/13/2012 : 12:45:44

But Sean's shirt is cooler (the Ford Speed Challenge!), Theo looks like he has an extra underbody warmer on, maybe to make him look bigger - to scare away the competition!

sean costin
human power supergeek

Lesotho
1919 Posts

Posted - 01/14/2012 : 11:23:53

I was all excited about getting my picture with one of my cycling heroes and Wow. I look like his coach. Note to self. Wear cap when being photographed with younger dudes.

Sean

Jackrabbit Jimmy
recumbent enthusiast

Canada
237 Posts

Posted - 01/15/2012 : 02:37:41

quote:
Originally posted by sean costin

I was all excited about getting my picture with one of my cycling heroes and Wow. I look like his coach. Note to self. Wear cap when being photographed with younger dudes.

Sean

It doesn't get any better with time Sean. In ten or fifteen years you will look at the same picture and say to yourself "I look so young in the picture".

Jackrabbit Jimmy

JMvD
New Member

70 Posts

Posted - 01/15/2012 : 23:29:42

quote:
Originally posted by Larry Lem

Gooly. He appears to a foot taller than Sean. At 7 feet, he'll tower over little-bitty Thomas and JM.

Larry Lem

Theo Bos is 190 cm which is 6 feet 2.8 inches (just like me)

cheers,

Jan-Marcel

Speedbiker
human power supergeek

USA
1996 Posts

Posted - 01/16/2012 : 07:50:11

So much for the idea that you can't be tall and go fast in a liner....

raptobike
Starting Member

Netherlands
24 Posts

Posted - 01/17/2012 : 07:41:57

Hi Speedbiker,

Theo is not the one racing. His brother Jan Bos will race the new Velox. Jan however is also around 1.90 meter. Sebastiaan is even taller.

If I remember correctly the assumption of the Delft team was that they could design a bike where having a big engine (and thus a fairly large bike) would out weigh the disadvantages. They specifically scout for taller riders.

Arnold.

Adam C
recumbent enthusiast

USA
219 Posts

Posted - 01/17/2012 : 10:40:30

quote:
Originally posted by raptobike

Hi Speedbiker,

Theo is not the one racing. His brother Jan Bos will race the new Velox. Jan however is also around 1.90 meter. Sebastiaan is even taller.

If I remember correctly the assumption of the Delft team was that they could design a bike where having a big engine (and thus a fairly large bike) would out weigh the disadvantages. They specifically scout for taller riders.

Arnold.

Is there a direct relationship with having a "big engine" and being tall?

Speedbiker
human power supergeek

USA
1996 Posts

Posted - 01/17/2012 : 11:09:07

Just my point. While not unimportant, hpv length and the resulting wet area is of lesser concern. Our CFD showed remarkable reduction in drag with a longer tail providing better pressure recovery. Look at the long tail on the Eiviestretto. Shorter isn't necessarily faster.
Now I don't feel bad for not making the Delft team....

25hz
human power supergeek

Canada
1217 Posts

Posted - 01/17/2012 : 11:52:17

Not at all, and physiologically, the larger a person, the lower the power to weight ratio is.

Speedbiker
human power supergeek

USA
1996 Posts

Posted - 01/17/2012 : 16:21:54

Yeah, but what about the watts? Once again, some factors are less important. Watts rule, and who's to say the heavier rider won't do better at BM? Obviously, Delft has their priorities right.

Larry Lem
human power supergeek

South Sandwich Islands
1971 Posts

Posted - 01/17/2012 : 18:36:14

My thoughts:

Battle Mountain-

Power versus drag trumps power vs. weight (assuming no one builds a 500 lb vehicle). Maximizing power while minimizing aero drag is the #1 concern. Decreasing rolling resistance is a concern, but a distant #2.

Low weight is important for acceleration with respect to the fixed distance of the runup. If a vehicle weighs a very large amount, then one could conclude that a longer runup is simply necessary. But the rider has a limited gas tank, so the lighter the vehicle, the better. Weight should also be minimized so that it doesn't contribute significantly to the forces preventing acceleration in the final 1 mile sprint. (Hopefully, the rider is fighting primarily aero drag, not mass).

Minimizing the weight will also reduce rolling resistance.

Larry Lem

Edited by - Larry Lem on 01/17/2012 18:40:10

Victor Ragusila
recumbent enthusiast

Canada
337 Posts

Posted - 01/17/2012 : 19:23:15

I agree with Larry on most accounts. Weight is important, but depends on the power profile. We are generally slow on the course, and try to sprint at the end to get more km/h. Todd is a sprinter, so we will try to reduce the weight of the bike a lot. A drop of 20lb (out of our 60lb bike) gives us 2km/h more at the top of the sprint. A good gain, but anyone going fast on the entire course will gain less.

Speedshaper, do you have any good references about presure recovery? I want to learn more about it. So far, Todd (he has been leading our AERO design) always tried to minimize area so the wetted area is minimum. We use the Standford pressure recovery profile (or somewhat similar) which minimizes the area while making sure there is no separation.

Rolling resistance is important however. I am curious if anyone else has calculations for this. We calculated that up to 110km/h our aero resistance is equal to the rolling resistance. We use 2 Stelvios in our bike.

I think delft did their homework better than almost anyone so far (having 4 people working full time for 1 year does that for you...) and they are very sure that bigger engines are worth the aero loss.

It will be interesting to see how they and Signus do next year versus Sam. We plan to have a bike somewhat similar to Velox and Signus, as it doesnt have any a canopy, but it smaller. This might give a good comparison between bigger and smaller similar bikes. Of course our aero will be much, much better :P

Victor

Adam C
recumbent enthusiast

USA
219 Posts

Posted - 01/17/2012 : 22:12:32

If "big engines" are worth the aero loss then I need to ask my 5'10", 165 lb female friend whose nickname is "quadzilla" to ride for me.

She's got freakish power for a girl.

Edited by - Adam C on 01/17/2012 22:13:42

Gugi100
New Member

Netherlands
78 Posts

Posted - 01/17/2012 : 23:06:09

quote:
Originally posted by Adam C

If "big engines" are worth the aero loss then I need to ask my 5'10", 165 lb female friend whose nickname is "quadzilla" to ride for me. She's got freakish power for a girl.

I didnot plan on coming to BM this year... But if you bring on Quadzilla.... that could make me reconsider.

:-)

Gr GJ

Adam C
recumbent enthusiast

USA
219 Posts

Posted - 01/17/2012 : 23:52:24

quote:
Originally posted by Gugi100

quote:
Originally posted by Adam C

If "big engines" are worth the aero loss then I need to ask my 5'10", 165 lb female friend whose nickname is "quadzilla" to ride for me. She's got freakish power for a girl.

I didnot plan on coming to BM this year... But if you bring on Quadzilla.... that could make me reconsider.

:-)

Gr GJ

Hmmm...I'll ask her.

My lead female rider is only 5'5", 125 lbs but she has "heart" and is an NCAA Division I distance runner with a well developed cardiovascular system.

Victor Ragusila
recumbent enthusiast

Canada
337 Posts

Posted - 01/18/2012 : 04:20:11

Best. bike. name. ever.

QUADZILLA!

Also, i definitely think that one should try to find the biggest rider for a given bike. If the bike is built, a smaller rider has very few advantages (unless they are more powerful, of course).

Edited by - Victor Ragusila on 01/18/2012 04:21:58

25hz
human power supergeek

Canada
1217 Posts

Posted - 01/18/2012 : 04:32:35

quote:
Originally posted by Larry Lem

My thoughts:

Battle Mountain-

Power versus drag trumps power vs. weight (assuming no one builds a 500 lb vehicle). Maximizing power while minimizing aero drag is the #1 concern. Decreasing rolling resistance is a concern, but a distant #2.

Low weight is important for acceleration with respect to the fixed distance of the runup. If a vehicle weighs a very large amount, then one could conclude that a longer runup is simply necessary. But the rider has a limited gas tank, so the lighter the vehicle, the better. Weight should also be minimized so that it doesn't contribute significantly to the forces preventing acceleration in the final 1 mile sprint. (Hopefully, the rider is fighting primarily aero drag, not mass).

Minimizing the weight will also reduce rolling resistance.

Larry Lem

Power to weight isn't about the weight, it's about where you start. A taller rider already has less comparative power for their size than a smaller person. That's the point. A taller person has the usable power of someone who is physically smaller. A physically smaller person can obviously fit in a smaller aero shell than the larger person. All things being equal, the smaller fairing will likely have the advantage aerodynamically.

That's all general info. If a taller rider has massive legs, well developed cardio and narrow shoulders, that muddies the waters. How do the performance curves stack up for a short stocky rider like Sam in a very small fairing, compared to a larger fairing with a narrow, large-legged rider? Lots of variables to consider with fairing length, width, height and shape, which of course is all dictated by who gets stuffed inside it and how much power they can produce. Strong thighs and narrow shoulders/chest are big bonuses for any size rider.

Larry Lem
human power supergeek

South Sandwich Islands
1971 Posts

Posted - 01/18/2012 : 07:27:38

"Power to weight isn't about the weight, it's about where you start. A taller rider already has less comparative power for their size than a smaller person. That's the point. A taller person has the usable power of someone who is physically smaller."

Unfortunately, I was not able to understand this. Could you please state it again in a different manner?

What does "where you start" mean, the length of the runup, or the size of the person you are starting with? It can't be the length of the runup because that is fixed at 5 miles (as we're not talking about an imaginary course). So I think you mean, "for a rider of a given size".

"A taller rider already has less comparative power for their size than a smaller person." Yes, but they have more power. And that is what the Delft team is pursuing as they think the higher power more than makes up for the increased aero drag caused by the larger vehicle resulting in a higher final speed.

Until the Delft team showed up, the general consensus was that a smaller, powerful rider and small vehicle would result in the fastest speed. (Just general, not shared by 100%)

"A taller person has the usable power of someone who is physically smaller." What does usable mean? Are you implying power density, size of vehicle, drag of vehicle, and resulting system balance (top speed)?

Larry Lem

Edited by - Larry Lem on 01/18/2012 07:29:17

Speedy
recumbent guru

USA
656 Posts

Posted - 01/18/2012 : 08:41:06

power to weight ratio

a 4,000 pound car with 1,000 HP (4/1 ratio)
will accelerate at the same rate as
a 1,000 pound car with 250 HP (4/1 ratio)
assuming the Coefficient of Drag is roughly similar

the Delft team seams to understand this concept
perhaps the one flaw in their design (my opinion)
is that the bike is not fitted to one rider, i.e. one size fits all ... or so it seems from this arm chair observation
the Varna / Sam combination has benefited from years of fit refinement helping to reduce the C of D

should Sam take up the Battle Mountain challenge again this year my guess is his fitness level will be quite high

Larry Lem
human power supergeek

South Sandwich Islands
1971 Posts

Posted - 01/18/2012 : 09:40:17

I think the "general consensus" over the years has been that power-to-weight ratio goes down as rider size increases.

And whether Delft agrees with this or not, I think they are more interested in power vs aero drag, that they can keep the aero drag from climbing too high as the size of the vehicle increases to accomodate the more powerful, larger rider.

Larry Lem

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