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Thread: "Dear Carleton"

  1. #2926
    Senior Member Impreza_aL's Avatar
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    but they would rub my pretty anodized cranks...

  2. #2927
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    Dear Carleton
    What do you think about the dosnoventa Houston frame for racing and training ?

  3. #2928
    Elitist carleton's Avatar
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    Quote Originally Posted by Jaredkemp View Post
    Dear Carleton
    What do you think about the dosnoventa Houston frame for racing and training ?
    I've never heard of it till just now, so I can't say. Looks like a street fixed gear, though. And integrated seat posts are not a good thing.

  4. #2929
    Senior Member Brian Ratliff's Avatar
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    Quote Originally Posted by carleton View Post
    I've never heard of it till just now, so I can't say. Looks like a street fixed gear, though. And integrated seat posts are not a good thing.
    1+

    It's got a road front end (slack head tube) and a track rear (steep seat tube and high bottom bracket). Pretty bike, but probably not the first pick for a velodrome.

    http://www.dosnoventabikes.com/faq.aspx#Geometry
    Cat 2 Track, Cat 3 Road.
    "If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter

  5. #2930
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    Quote Originally Posted by carleton View Post
    I've never heard of it till just now, so I can't say. Looks like a street fixed gear, though. And integrated seat posts are not a good thing.
    Quote Originally Posted by Brian Ratliff View Post
    1+

    It's got a road front end (slack head tube) and a track rear (steep seat tube and high bottom bracket). Pretty bike, but probably not the first pick for a velodrome.

    http://www.dosnoventabikes.com/faq.aspx#Geometry
    thanks guys , i would think an integrated seatpost is more aero though mind explaining?

  6. #2931
    Senior Member Brian Ratliff's Avatar
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    Quote Originally Posted by Jaredkemp View Post
    thanks guys , i would think an integrated seatpost is more aero though mind explaining?
    It's not adjustable, and if you ever have to ship the bike, it'll make it difficult to pack. But on the other hand, if your saddle height is dialed in to +-0.5 inches and you don't care about shipping, it is a slick way of getting a really stiff, very light, seatpost built straight into the bike. Lots of custom builders do this because it 1) allows for a lighter frame, and 2) differentiates their frames from mass produced frames.
    Cat 2 Track, Cat 3 Road.
    "If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter

  7. #2932
    Elitist carleton's Avatar
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    Quote Originally Posted by Jaredkemp View Post
    thanks guys , i would think an integrated seatpost is more aero though mind explaining?
    1) An "aero" seatpost doesn't provide much (if any) aero benefit. Think about it. Your legs are churning up air like an egg beater right in front of it. That air is so "dirty" (meaning not smooth) that an aero seatpost can't do much to save it.

    2) This "aero" seatpost on the Houston frame is round...just like any other round seatpost. So, it's thicker and no more round than a standard 27.2 post which actually makes it less aero...if aero seatposts were a real factor in aerodynamics

    3) Integrated Seat Posts (ISP) create an obvious problem: Once you cut it, you can't un-cut it. So, if you cut it too short, you are sh*t out of luck. You can't even hover the cap over the post on this bike because the cap sits inside of the mast of the ISP. When you train/race, you'll adjust your seatpost a lot for various reasons (drop vs aerobars, new saddle setback, adjusting pedaling style, adjusting leg reach). So, when you buy this bike you can't do any of that. You get one chance and that's it. This is reason enough to avoid this bike, for track or street use.

    4) This is a bad bike with a nice paint job.

  8. #2933
    Resident Alien Racer Ex's Avatar
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    Quote Originally Posted by carleton View Post
    1) An "aero" seatpost doesn't provide much (if any) aero benefit. Think about it. Your legs are churning up air like an egg beater right in front of it. That air is so "dirty" (meaning not smooth) that an aero seatpost can't do much to save it.
    The set up question for this theory is:

    Then that should apply to the whole back of the bike, correct?

    It doesn't because that assumption isn't valid though on face value it looks like it could be. You shape flow and attach dirty air as much as possible to stop turbulence in the first place or reduce/remove it when you can, which is what an aero post does, just like shaped seat stays, chain stays, and a disc rear wheel, all of which sit behind that same dirty air.

    Watch some smoke tests some time when they put a foil behind something creating turbulence. You get less turbulence. Same thing happens with an aero seat post in smoke tests.

    How much of a benefit an "aero" seat post is depends on the rider, length of post, and a bunch of other variables and is a case by case number. A watt is a watt, two watts is two watts, Etc.

    The rest of the objections to integrated or proprietary posts, some quite valid (though not the one about cutting it too short unless you go completely insane...most ISP have several cm of usable shim stack under the clamp), are part of a cost/benefit analysis of what that number is worth. Especially if you can use an aero post like Burrows designed.
    Last edited by Racer Ex; 01-03-14 at 01:42 PM.

  9. #2934
    Elitist carleton's Avatar
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    Quote Originally Posted by Racer Ex View Post
    The set up question for this theory is:

    Then that should apply to the whole back of the bike, correct?
    Nope

    Quote Originally Posted by Racer Ex View Post
    It doesn't because that assumption isn't valid though on face value it looks like it could be. You shape flow and attach dirty air as much as possible to stop turbulence in the first place or reduce/remove it when you can, which is what an aero post does, just like shaped seat stays, chain stays, and a disc rear wheel, all of which sit behind that same dirty air.

    If you really want to clean up the dirty air created by the legs, you can remove the top tube. That's what Mr. Tiemeyer told me was the reason that his team did that on this bike:


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    Senior Member VanceMac's Avatar
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    Quote Originally Posted by carleton View Post
    That bike is hot. And as much as I'm a fan of engineering and innovation (Obree forever!), I really hope the Katsanis UCI appointment doesn't mean we have to re-invest in a whole new fleet.

  11. #2936
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    For some vintage comments on seatposts there is an interview with John Cobb (on the 'new' compact frame designs).
    http://www.slowtwitch.com/mainheadin...r/compact.html
    The summary is that for skinny posts round is better but thicker posts work better with a tail - all of this with a rider. The thicker post is supposed to help keep air out from between the legs.
    My guess is that with a skinny post the air off the legs is coming in at a high angle so the airfoil is getting a side wind and stalling where round is the same for all the angles.

    As far as integrated posts I like the idea on the Felt TK1 with a removable/replaceable integrated like post so it will not slip like most non integrated aero posts yet does not require a new frame when you get a different seat. I have not tried one so this is all theory where anything works.

  12. #2937
    Resident Alien Racer Ex's Avatar
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    Quote Originally Posted by carleton View Post
    If you really want to clean up the dirty air created by the legs, you can remove the top tube. That's what Mr. Tiemeyer told me was the reason that his team did that on this bike:

    I wish I could dig it up but there was a Brit who made fairings we wore on his arms and calfs. Looked...odd. Probably worked though.

    I am with Vance on the innovation side and my hope that the UCI starts embracing change.

    Too bad Tiemeyer retired. I'm having a heck of a time finding someone to build an aero tandem.

    My buddy is Cobb's data recorder. John's a mad scientist and not someone who gets locked into dogma. His seatpost theories dovetail with some of his bottle tests where he ran an aero bottle vs. a round bottle. Some folks were faster with one, others with the other. That goes back to my long post above about the aero stuff being interactive.

    Shot of me on the old track bike at A & M with Cobb...and some wheel tests.

    IMG-20110324-00087.jpg

    Wheels copy.jpg

    And as Robbie Ketchell's (now the Garmin aero guru) bike model

  13. #2938
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    I live in Portland, who would you recommend for a quality bike fit?
    Thanks

  14. #2939
    Elitist carleton's Avatar
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    Quote Originally Posted by cdat12 View Post
    I live in Portland, who would you recommend for a quality bike fit?
    Thanks
    Check with Kirk Whiteman. I'm not sure if he offers it as a service. He really knows his stuff.

    http://tempocycles.com/html_home.cfm...9723&load=html
    https://www.facebook.com/pages/Kirk-...81693791871132

    Also check with Bike Central: http://www.bike-central.com/service_menu.html

    A bike fit usually runs $75-100. It's definitely worth it if you can afford it, especially for a new rider.

    If you don't go with one of them, at least try to get a bike fitter that is familiar with track racing. In track racing the races are only a few minutes long as opposed to a 30 minute criterium or a 2+ hour road race. Most beginner track races are 5-15 minutes. So, a more aggressive (and less comfortable) position will work.

    I've only been in Portland about a year so I don't know that many resources. Maybe Brian can chime in.

  15. #2940
    Senior Member Brian Ratliff's Avatar
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    Russell Cree at Upper Echelon did my bike fit a few years ago. He knows his stuff. Basically, unless you are complaining about back issues (or something is really out of whack), he doesn't really do much with the upper body; he is more about the leg motion. He is not a trackie, but he is up to date on racing cyclist biomechanics. He's got a fancy motion tracking machine. I recommend him primarily because when I went in, I had already been racing a few years; thought my position was pretty good (until I started getting some niggling injuries). He looked at me with that motion tracking machine, raised my saddle like a full inch, and all my troubles literally went away. Goes to show the limits of a self-fit.

    At Bike Central, Dean will fit you by eye, watching you as you ride. He's not a fit specialist per se, but he does know what a good fit looks like and a lot of guys swear by him. Just ask. He might bite your head off, but only if you deserve it .

    Those are the only two I know about personally. Russell will put you back a C note or two. Good fits are not cheap. Don't know what Dean charges.
    Cat 2 Track, Cat 3 Road.
    "If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter

  16. #2941
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    Thanks to both of you for the suggestions, I had Russell do my road bike fit, didn't know if there was someone that specialized in track bikes. Will go back to Russell, liked what he did. Looking forward to learning about and trying track when Alpenrose starts their classes. .

    John

  17. #2942
    Elitist carleton's Avatar
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    Quote Originally Posted by cdat12 View Post
    Thanks to both of you for the suggestions, I had Russell do my road bike fit, didn't know if there was someone that specialized in track bikes. Will go back to Russell, liked what he did. Looking forward to learning about and trying track when Alpenrose starts their classes. .

    John
    I just got a reply from Kirk. He suggests Ward Griffins at River City Bicycles. He highly recommends her.

  18. #2943
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    Thanks


    Quote Originally Posted by carleton View Post
    I just got a reply from Kirk. He suggests Ward Griffins at River City Bicycles. He highly recommends her.

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