rolldown tests (longish)

Discussion in 'Recumbent bicycles' started by Mikael Seierup, Jun 8, 2003.

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  1. Made in Denmark. Unfortunately in danish. However its a good chance to see some danish homebuilts if
    you squint at the small pictures. ;-) Torben Scheel might have the originals in a larger size.

    http://www.hpv-klub.dk/Arrangementer/03-05-10_rulletest/default.asp

    I will translate the comments for each of the bikes:

    Odense Special:

    1: loosefitting clothes.

    Comments: Samme airresistance as the other highracer of the test, the Lolita. This rider is more
    heavily built which indicates that the bike is a bit more aerodynamic. This is probably due to the
    higher bottom bracket on the Odense Special.

    Kildemoes damecykel:

    2: Loosefitting clothes, box on rack, hands at the middle of the handlebars, upper body crouched
    over handlebars to minimize airresistance.

    Comments: The only upright was tested with the rider crouched over the handlebars which more or less
    resembles the position on a roadbike. The airresistance was equal to the highracers despite the
    rider being much smaller.

    Leitra:

    3: With full fairing and wheelfairings.
    4: Without faring but with wheelfairings.
    5: Without fairing and wheelfairings.

    Comments: The Leitra is the bike with the worst aerodynamics when riding sans fairing. Probably due
    to the very upright seatposition. The two frontwheels adds a fair bit of drag that is markedly
    reduced when the wheelfairings are utilized. With its fairing on its fairly aerodynamic but is not
    significantly faster on the road due to its weight.

    Hjemmelavet forhjulstrukket lowracer (homemade FWD yada, yada)

    6: Tailfairing, T-shirt.
    7: Tailfairing with 6 kg of luggage, loosefitting clothes
    8: Tailfairing, loosefitting clothes, rainjacket.
    9: No fairing, loose clothes.
    10: No fairing, loose clothes, rainjacket.

    Comments: Attempt 2 should have yielded more airresistance than 1. That this is not the case is
    probably a measurement error. On the other hand its obvious that the rainjacket add a significant
    amount of drag. The tailfairing reduces the airresistance by ~25% whichs nets you 2-3 kph.

    Optima Baron:

    11: tightfitting clothes, wheeldisc on front wheel, aerohelmet
    12: Tight clothes, 18 spoke front wheel, aerohelmet.
    13: Tight clothes, wheeldisc on front, ordinary helmet
    14: Tight clothes, wheeldisc on front, ordinary helmet, backpack dangling on arm

    Comments: The most aerodynamic bike of this test. The first three tries have been repeated many
    times to reduce statistical error, so the results are very reliable. The wheeldisc and the
    aerohelmet seems to reduce drag by 5 and 6 percent respectively, which nets you 0.5-1 kph. In
    attempt 4 the backpack is dangling on one arm and totally ruins the aerodynamics and dramatically
    doubles the airresistance.

    Homemade Zox-clone:

    15: Tightfitting clothes, small seatbags.

    Comments: This lowracer has lower drag than most of the other bikes. But the tires Schwalbe City
    Marathon has a rather high rolling resistance, which slows it down.

    Homemade FWD with tailfairing:

    16: Tight clothes.

    Comments:

    Despite its low seatheight and a tailfairing this bike displays relatively high airresistance. Most
    likely due to the upright seatingposition. The tailfairing probably doesn't help much either apart
    from being handy to store stuff in as its too short for the upright seat. However the bike is still
    relatively fast due to its Schwalbe Stelvio tires.

    Homemade "Lolita" highracer.

    17: loosefitting jacket.
    18: loosefitting jacket, topbag behind seat.
    19: loose jacket, topbag, arms in superman position

    Comments: The Vittoria Corsa EVO CX tires makes the bike relatively fast in relation to the other
    highracer of the test that has the same airresistance. The topbag does not affect anything
    significantly but the position of the arms does. When the handlebars are tilted forward so the arms
    are extended (superman) the airresistance is reduced by 18% which nets you 2 kph.

    Evita-2:

    20: Tightfitting clothes
    21: Loose clothing
    22: Dressed for touring with bags

    Comments: This quasilow bike has relatively low airresistance. This is probably due to the narrow
    handlebars that keeps the arms close to the body and partly because the seat covers the top part of
    the rear wheel. Loose clothing means 6% more drag. Flapping clothes for touring and bags increases
    drag significantly. In this case nearly 50 %.

    Evita-1:

    23: No helmet or jacket.
    24: No helmet, loosefitting jacket.
    25: helmet, jacket, bag, waterbottle

    Comments: The old model of the Evita is a bit slower than the new. This is partly due to the larger
    rider but probably also that the rearwheel is not out of the airflow behind the seat. The jacket
    increases drag by 4% and all the kit increases it yet another 4%.

    Regards Mikael

    Note: I just translated it so I cannot argue the pros and cons of the conclusions and
    assumptions. All errors and typos are mine unless I can come up with a plausible excuse or
    blame someone else. ;-)
     
    Tags:


  2. Mikael,

    Thank you for finding this site, and for translating.

    Too bad they didn't do all the runs with the same rider.

    Some take-home insights:

    The rider, by far, is the largest contributor to drag. Get a slim rider in aero position, tight
    cloths, and aero helmet.

    Tail fairings won't offset a big rider in loose clothing.

    Even a full fairing doesn't guarantee low aero drag.

    A small, poorly designed tail fairing/bag won't help. It won't hurt either.

    Hi racers appear about as aero as low, and semi low-racers.

    Warren
     
  3. Mikael - thank you for the data and translation.

    Chris
     
  4. "Warren Berger" skrev...
    > Thank you for finding this site, and for translating.

    Our danish HPV-site so it wasn't all that hard to find. ;-)

    > Hi racers appear about as aero as low, and semi low-racers.

    Oh? I don't feel the data supports that. Or rather the tailfaired Baron with assorted aerogoodies
    got em all beat. 7-10 kph is quite a difference in my book. You could probably reduce that gap by
    tailfairing them but only by 3-4 kph.

    Btw. the piece was written by Mark Olaf Slot and the webmagic was performed by Torben Scheel.

    M.
     
  5. Mads Hilberg

    Mads Hilberg Guest

    > http://www.hpv-klub.dk/Arrangementer/03-05-10_rulletest/default.asp
    >

    Very interesting. Do you know if there are any plans to expand this? Obvious omissions are some
    retail 26/20 SWB recumbents, your Velokraft, a fully faired bike, the effect of various trailers and
    some more trikes. It would also be interesting to take a bike with USS and compare it with itself
    (!) in an OSS configuration.

    Maybe we could translate the site to English, post the methodology and invite people to add to
    the database.

    Mads
     
  6. "Mads Hilberg" skrev

    > Very interesting. Do you know if there are any plans to expand this? Obvious omissions are some
    > retail 26/20 SWB recumbents, your Velokraft, a fully faired bike, the effect of various trailers
    > and some more trikes. It would also be interesting to take a bike with USS and compare it with
    > itself (!) in an OSS configuration.

    Just arrange it with Mark. The hill they use is west of Odense. I just didn't have time to go there
    plus Storebælt presents a challenge when it comes to bringing recumbents on the train.

    Or we could try to dig up some suitable hills around the country depending on how amenable to change
    his computerprogram is.

    M.
     
  7. "Mikael Seierup" skrev ...
    > Or we could try to dig up some suitable hills around the country depending on how amenable to
    > change his computerprogram is.

    Talking to myself and Mads so it will be in Danish. Sorry ;o)

    Der er faktisk en god bakke lige før man kører ind i Farum, når man følger cykelstien op langs
    Hillerød (Farum?) motorvejen. Den har cykelsti med god overflade og træer langs siderne, der giver
    læ og vigtigst af alt ingen væsentlige sideveje eller kryds. Den går i en blid kurve mod højre, men
    intet der nødvendiggør bremser. Desuden er der en bro nede for enden af den, man kan stå under, hvis
    vejret driller. Jeg kommer som regel op på en 50-60 km/t uden at træde.

    Det hjælper selvfølgelig ikke dig oppe i det mørke og flade Jylland. ;.)

    mvh Mikael
     
  8. Mads Hilberg

    Mads Hilberg Guest

    > Just arrange it with Mark. The hill they use is west of Odense.

    Okay - once I have my StreetMachine I'll contact him. We can try it with and without panniers,
    trailer, SON dynamo hub on/off, etc. If I can mount the fairing, that could be tried also, although
    I wasn't able to fit it onto my friend's SMGT with the brackets you sold it to me with - the cable
    guide for the front derailleur was in the way. Rather odd seeing as the fairing is made by
    HPVelotechnik!! Guess I'll need a different mounting bracket.

    > I just didn't have time to go there plus Storebælt presents a challenge when it comes to bringing
    > recumbents on the train.

    Now that's just a myth. I've taken my recumbent and Bob Yak with me loads of times all the way from
    Copenhagen to Thisted with no problems (sometimes with the fairing mounted!). Sometimes I've been
    given a bike reservation, other times a pram reservation. Either way the conductors have never
    minded and I've never had any problems with other passengers either. Just remember to book a couple
    of days in advance and don't tell the ticket staff that your bike is a recumbent and don't mention
    your trailer. I think it'd be more problematic with a tandem (or a trailer so big it can't be
    stacked on top of the bike) though.

    Of course it's not a myth that you didn't have time :)

    Mads
     
  9. Mikael,

    > > Hi racers appear about as aero as low, and semi low-racers.
    >
    > Oh? I don't feel the data supports that.

    I wish I had more info, in English.

    But look at the 250 W speeds, which should magnify any aero differences. The Baron is using some, or
    all, aero tricks known to man on its runs. The high racers are using none. No tight cloths, no aero
    helmets, no wheel discs, no tail fairings. The Baron is the only low or semi-low to clearly beat the
    high racers. The only other faster low or semi-low is the one with the huge tail fairing. Without
    the fairing, or with loose cloths, it is slower!

    > Or rather the tailfaired Baron with assorted aerogoodies got em all beat.

    Again, if it didn't win using everything short of a full fairing something would be terribly wrong.

    Warren
     
  10. Gary Mc

    Gary Mc Guest

    "Mikael Seierup" <[email protected]> wrote in message
    news:<[email protected]>...
    > "Mikael Seierup" skrev ...
    > > Or we could try to dig up some suitable hills around the country depending on how amenable to
    > > change his computerprogram is.
    >
    > Talking to myself and Mads so it will be in Danish. Sorry ;o)
    >
    >

    Being stationed in Europe a couple of times, Danish was the hardest language for me to get any
    handle on. In every other language that I had to use at least "beer" sounded about the same as
    English. In Danish It is spelled something like "oel" using the English aphabet: but, asking for
    "oil" never got me what I wanted. Luckily, most Danes that I met are bilingual, trilingual or
    whatever. They are also very patient with others who stumble badly in their language.

    Gary McCarty, Greenspeed GTO, Salt Lake City
     
  11. In article <[email protected]>, [email protected] says...
    > In every other language that I had to use at least "beer" sounded about the same as English. In
    > Danish It is spelled something like "oel" using the English aphabet: but, asking for "oil" never
    > got me what I wanted.

    Did you ever try asking for 'ale'? For that is the likely the English counterpart. Beer is bier and
    then I had to ask for a 'Pivo' in Prague. I never did find out what beer was in Hungarian. But then
    I don't think the Hungarians ever found out what beer/bier was to give it a Hungarian/Magyar name.

    --
    Cletus D. Lee Bacchetta Giro Lightning Voyager http://www.clee.org
    - Bellaire, TX USA -
     
  12. "Mikael Seierup" <[email protected]> wrote in message
    news:[email protected]...
    > Made in Denmark. Unfortunately in danish. However its a good chance to see some danish homebuilts
    > if you squint at the small pictures. ;-) Torben Scheel might have the originals in a larger size.
    >
    > http://www.hpv-klub.dk/Arrangementer/03-05-10_rulletest/default.asp
    >
    > I will translate the comments for each of the bikes:

    I guess I'll have to get to work now, thanks for the translation. If you fall into a timegap, feel
    free to translate the rest ;-)

    >
    > Odense Special:
    >
    > 1: loosefitting clothes.
    >
    > Comments: Samme airresistance as the other highracer of the test, the
    Lolita.
    > This rider is more heavily built which indicates that the bike is a bit
    more aerodynamic.
    > This is probably due to the higher bottom bracket on the Odense Special.
    >
    > Kildemoes damecykel:
    >
    > 1: Loosefitting clothes, box on rack, hands at the middle of the
    handlebars, upper body
    > crouched over handlebars to minimize airresistance.
    >
    > Comments: The only upright was tested with the rider crouched over the
    handlebars
    > which more or less resembles the position on a roadbike. The airresistance
    was equal
    > to the highracers despite the rider being much smaller.
    >
    > Leitra:
    >
    > 1: With full fairing and wheelfairings.
    > 2: Without faring but with wheelfairings.
    > 3: Without fairing and wheelfairings.
    >
    > Comments: The Leitra is the bike with the worst aerodynamics when riding
    sans fairing.
    > Probably due to the very upright seatposition. The two frontwheels adds a
    fair bit of drag
    > that is markedly reduced when the wheelfairings are utilized. With its
    fairing on its fairly
    > aerodynamic but is not significantly faster on the road due to its weight.
    >
    > Hjemmelavet forhjulstrukket lowracer (homemade FWD yada, yada)
    >
    > 1: Tailfairing, T-shirt.
    > 2: Tailfairing with 6 kg of luggage, loosefitting clothes
    > 3: Tailfairing, loosefitting clothes, rainjacket.
    > 4: No fairing, loose clothes.
    > 5: No fairing, loose clothes, rainjacket.
    >
    > Comments: Attempt 2 should have yielded more airresistance than 1. That this is not
    the case
    > is probably a measurement error. On the other hand its obvious that the
    rainjacket
    > add a significant amount of drag. The tailfairing reduces the
    airresistance by ~25%
    > whichs nets you 2-3 kph.
    >
    > Optima Baron:
    >
    > 1: tightfitting clothes, wheeldisc on front wheel, aerohelmet
    > 2: Tight clothes, 18 spoke front wheel, aerohelmet.
    > 3: Tight clothes, wheeldisc on front, ordinary helmet
    > 4: Tight clothes, wheeldisc on front, ordinary helmet, backpack dangling
    on arm
    >
    > Comments: The most aerodynamic bike of this test. The first three tries have been
    repeated many times
    > to reduce statistical error, so the results are very reliable. The
    wheeldisc and the aerohelmet
    > seems to reduce drag by 5 and 6 percent respectively, which nets you 0.5-1
    kph.
    > In attempt 4 the backpack is dangling on one arm and totally ruins the
    aerodynamics
    > and dramatically doubles the airresistance.
    >
    > Homemade Zox-clone:
    >
    > 1: Tightfitting clothes, small seatbags.
    >
    > Comments: This lowracer has lower drag than most of the other bikes. But the tires Schwalbe City
    > Marathon has a rather high rolling resistance, which slows
    it down.
    >
    > Homemade FWD with tailfairing:
    >
    > 1: Tight clothes.
    >
    > Comments:
    >
    > Despite its low seatheight and a tailfairing this bike displays relatively
    high airresistance.
    > Most likely due to the upright seatingposition. The tailfairing probably
    doesn't help much
    > either apart from being handy to store stuff in as its too short for the
    upright seat.
    > However the bike is still relatively fast due to its Schwalbe Stelvio
    tires.
    >
    > Homemade "Lolita" highracer.
    >
    > 1: loosefitting jacket.
    > 2: loosefitting jacket, topbag behind seat.
    > 3: loose jacket, topbag, arms in superman position
    >
    > Comments: The Vittoria Corsa EVO CX tires makes the bike relatively fast in relation
    to
    > the other highracer of the test that has the same airresistance. The topbag does not affect
    > anything significantly but the position of the
    arms does.
    > When the handlebars are tilted forward so the arms are extended (superman) the airresistance is
    > reduced by 18% which nets you 2 kph.
    >
    > Evita-2:
    >
    > 1: Tightfitting clothes
    > 2: Loose clothing
    > 3: Dressed for touring with bags
    >
    > Comments: This quasilow bike has relatively low airresistance. This is
    probably due to
    > the narrow handlebars that keeps the arms close to the body and partly
    because the seat
    > covers the top part of the rear wheel. Loose clothing means 6% more drag.
    Flapping clothes
    > for touring and bags increases drag significantly. In this case nearly 50
    %.
    >
    > Evita-1:
    >
    > 1: No helmet or jacket.
    > 2: No helmet, loosefitting jacket.
    > 3: helmet, jacket, bag, waterbottle
    >
    > Comments: The old model of the Evita is a bit slower than the new. This is partly
    due to the larger rider
    > but probably also that the rearwheel is not out of the airflow behind the
    seat.
    > The jacket increases drag by 4% and all the kit increases it yet another
    4%.
    >
    >
    > Regards Mikael
    >
    > Note: I just translated it so I cannot argue the pros and cons of the
    conclusions
    > and assumptions. All errors and typos are mine unless I can come up with a
    plausible
    > excuse or blame someone else. ;-)
     
  13. > Hi racers appear about as aero as low, and semi low-racers.

    Yes, but in a real world comparison, the low ones will go faster, as the windspeed near the
    ground is lower.

    Torben
     
  14. "Mikael Seierup" <[email protected]> wrote in message
    news:[email protected]...

    > Der er faktisk en god bakke lige før man kører ind i Farum, når man følger cykelstien op langs
    > Hillerød (Farum?) motorvejen. Den har cykelsti med god overflade og træer langs siderne, der giver
    > læ og vigtigst af alt ingen væsentlige sideveje eller kryds. Den går i en blid kurve mod højre,
    > men intet der nødvendiggør bremser. Desuden er der en bro nede for enden af den, man kan stå
    > under, hvis vejret driller. Jeg kommer som regel op på en 50-60 km/t uden at
    træde.

    Alternativt er der en stejl en på vejen fra Lynge til Ganløse (tæt ved ganløse). Jeg tror at den vil
    være bedre, da den er en del hurtigere, og stejlere i starten.
    >
    > Det hjælper selvfølgelig ikke dig oppe i det mørke og flade Jylland. ;.)
    >
    > mvh Mikael
     
  15. "Torben Scheel"

    > I guess I'll have to get to work now, thanks for the translation. If you fall into a timegap, feel
    > free to translate the rest ;-)

    A timegap would be neat. Then I might have time to meet my deadline.

    M.
     
  16. "Gary Mc" <[email protected]> wrote in message
    news:[email protected]...
    > Being stationed in Europe a couple of times, Danish was the hardest language for me to get any
    > handle on. In every other language that I had to use at least "beer" sounded about the same as
    > English. In Danish It is spelled something like "oel" using the English aphabet: but, asking for
    > "oil" never got me what I wanted.

    No problem these days, every other pub is Irish now. Asking for øl can be a problem sometimes :-|
     
  17. "Torben Scheel"

    > Alternativt er der en stejl en på vejen fra Lynge til Ganløse (tæt ved ganløse). Jeg tror at den
    > vil være bedre, da den er en del hurtigere, og stejlere i starten.

    Broskov bakke? Ned mod Ganløse eller mod Bastrup Sø? Jeg må et smut forbi den en dag og se. Har den
    cykelsti og læ?

    mvh Mikael
     
  18. "Mikael Seierup" <[email protected]> wrote in message
    news:[email protected]...

    > Broskov bakke? Ned mod Ganløse eller mod Bastrup Sø?
    Jeps, det vidste jeg ikke at den hed. Forbi Ganløse Eged nordfra ad lyngevej efter Bastrup Sø

    > Jeg må et smut forbi den en dag og se. Har den cykelsti og læ?
    Kun læ, men normalt ikke så meget trafik.

    vh Torben
     
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