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  #961  
Old 02-18-12, 17:27
FrankDay FrankDay is offline
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Originally Posted by marathon marke View Post
Frank, how would raising your seat made you more aero?
if you accept that lowering your handlebars will make you more aero then raising the seat is doing the exact same thing (because it is the relationship between the seat and the handlebars that determine upper body position). In the video I linked when starting this thread I have an animated explanation as to why in that the hips get moved into the wind shadow of the shoulders as the seat goes up or the handlebars go down. The other change that happens is, as the back gets flatter, the head moves more forward and down in relation to the shoulders, this also causes the head to stick up less above the shoulder, again reducing frontal area.
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  #962  
Old 02-25-12, 02:10
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Because of the interest we have seen in short cranks and because of the number of PC'ers who have decided to race on shorter PC's this year we have decided to come up with a short PC for racing. These are available from sizes ranging from 142.5. to 75 mm. Pictured is my own 105 mm cranks mounted on my bicycle with compact 50/34 chain rings. Within the next month or so I will have available shorter cranks of the "regular crank" variety for those who don't give a whoot(sp?) about pedaling in the PC fashion but see an advantage to shorter cranks. While short cranks are available though other sources, the shown crankarm itself weighs about 140 gm but we expect our fixed crank arms should weigh about 100 gms (depending upon the length) for the weight weenies, when available. Also note the picture shows the spider being made out of a soon to be available composite material in the final stages of testing for further weight reduction. Enjoy.
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  #963  
Old 02-25-12, 04:28
marathon marke marathon marke is offline
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Originally Posted by FrankDay View Post
Another anecdotal report (sorry Fergie, it is the best I can do) from the same source as the last time, just an earlier edition.
Quote:
Originally Posted by FrankDay View Post
if you accept that lowering your handlebars will make you more aero then raising the seat is doing the exact same thing (because it is the relationship between the seat and the handlebars that determine upper body position). In the video I linked when starting this thread I have an animated explanation as to why in that the hips get moved into the wind shadow of the shoulders as the seat goes up or the handlebars go down. The other change that happens is, as the back gets flatter, the head moves more forward and down in relation to the shoulders, this also causes the head to stick up less above the shoulder, again reducing frontal area.
I think I'm understanding you correctly, Frank. But I have a question. If you are already riding comfortably with a flat back on long (175) crank arms, then wouldn't raising the saddle (for the shorter arms) effectively make one less aero?

Can you direct me to that video you are referring to? I an't seem to find it.
Thanks.
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Last edited by marathon marke; 02-25-12 at 04:31.
  #964  
Old 02-25-12, 05:41
FrankDay FrankDay is offline
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Originally Posted by marathon marke View Post
I think I'm understanding you correctly, Frank. But I have a question. If you are already riding comfortably with a flat back on long (175) crank arms, then wouldn't raising the saddle (for the shorter arms) effectively make one less aero?

Can you direct me to that video you are referring to? I an't seem to find it.
Thanks.
For that rider "already riding comfortably with a flat back on long (175) crank arms", unless the head is already below the highest point of the back/**** it is pretty unlikely that raising the seat and **** will increase the frontal area and make one less aero. The frontal area is not going to increase unless the **** is moved out of the wind shadow of the trunk/shoulders. The number of people for whom this condition currently exists is, I would estimate, approximately zero but I would give you that it is theoretically possible. I guess that is why one needs to try it and see if it works for you or not.

Here is the link to the video i made: http://www.youtube.com/watch?v=HFxBg7BnFlQ

Frank
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  #965  
Old 02-25-12, 06:27
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Originally Posted by FrankDay View Post
Because of the interest we have seen in short cranks and because of the number of PC'ers who have decided to race on shorter PC's this year we have decided to come up with a short PC for racing. These are available from sizes ranging from 142.5. to 75 mm. Pictured is my own 105 mm cranks mounted on my bicycle with compact 50/34 chain rings. Within the next month or so I will have available shorter cranks of the "regular crank" variety for those who don't give a whoot(sp?) about pedaling in the PC fashion but see an advantage to shorter cranks. While short cranks are available though other sources, the shown crankarm itself weighs about 140 gm but we expect our fixed crank arms should weigh about 100 gms (depending upon the length) for the weight weenies, when available. Also note the picture shows the spider being made out of a soon to be available composite material in the final stages of testing for further weight reduction. Enjoy.
this must be that custom bike built for the actor who plays Tyrione Lannister
  #966  
Old 02-25-12, 08:21
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So what did we decide about crank length?
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Last edited by Maxiton; 02-25-12 at 08:26.
  #967  
Old 02-25-12, 08:29
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Varying definitions of importance.
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  #968  
Old 02-25-12, 11:29
simo1733 simo1733 is offline
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Quote:
Originally Posted by FrankDay View Post
Because of the interest we have seen in short cranks and because of the number of PC'ers who have decided to race on shorter PC's this year we have decided to come up with a short PC for racing. These are available from sizes ranging from 142.5. to 75 mm. Pictured is my own 105 mm cranks mounted on my bicycle with compact 50/34 chain rings. Within the next month or so I will have available shorter cranks of the "regular crank" variety for those who don't give a whoot(sp?) about pedaling in the PC fashion but see an advantage to shorter cranks. While short cranks are available though other sources, the shown crankarm itself weighs about 140 gm but we expect our fixed crank arms should weigh about 100 gms (depending upon the length) for the weight weenies, when available. Also note the picture shows the spider being made out of a soon to be available composite material in the final stages of testing for further weight reduction. Enjoy.
[IMG]https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/p480x480/431614_10150688725135126_619090125_11812337_965556 9
58_n.jpg[/IMG]
Do you have difficulty putting your foot down when you unclip?
  #969  
Old 02-25-12, 17:04
FrankDay FrankDay is offline
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Do you have difficulty putting your foot down when you unclip?
No. I do have to come off the saddle but it has never been something I even thought about.

Edit: I have been told that there is one Italian frame maker who is now making frames with lower BB's specifically for shorter cranks.
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Last edited by FrankDay; 02-25-12 at 17:10.
  #970  
Old 02-28-12, 23:26
coapman coapman is offline
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Quote:
Originally Posted by FrankDay View Post
Because of the interest we have seen in short cranks and because of the number of PC'ers who have decided to race on shorter PC's this year we have decided to come up with a short PC for racing. These are available from sizes ranging from 142.5. to 75 mm. Pictured is my own 105 mm cranks mounted on my bicycle with compact 50/34 chain rings. Within the next month or so I will have available shorter cranks of the "regular crank" variety for those who don't give a whoot(sp?) about pedaling in the PC fashion but see an advantage to shorter cranks. While short cranks are available though other sources, the shown crankarm itself weighs about 140 gm but we expect our fixed crank arms should weigh about 100 gms (depending upon the length) for the weight weenies, when available. Also note the picture shows the spider being made out of a soon to be available composite material in the final stages of testing for further weight reduction. Enjoy.

Latest research from Australia confirms PC's do not increase power output.
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