Frame Size

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Frame Size

Postby the crazyest vegan » Mon Oct 20, 2008 10:28 pm

i measure my frame today and from the centre of the headtube to the centre of the seatpost it is 53cm
i'm 5.7 and am going to by a new frame soon but am going for a 50cm for weight and position advantages.
what length is your bike and how tall are you??
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Postby Man On Bike. » Mon Oct 20, 2008 11:51 pm

Hmmm.

I dunno how tall I am exactly, they're just numbers innit, but I seem to remember being 6'2" or something.

I used to ride a 60, which was the correct height but too long.

I now ride the same frame but 58, which still feels too long up front, but feels like a BMX compared to the 60cm frame. I have to have the seatpost really really f***ing long for it to be the right height. I also have 5cm of spacers under my stem ffs. And that's with riser bars. If I had flat bars I'd need another 2cm of spacers underneath. My bike looks silly.
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Postby the crazyest vegan » Tue Oct 21, 2008 12:16 am

is the bike your on about the one in your picture? i think the seatpost look's good, i was considering buying a teeny compact frame and doing crazy shiz like that but it's too expensive so i'm not going to bother with that.
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Postby Mr. Cleetus » Tue Oct 21, 2008 12:57 am

neither of my two main bikes are standard sizing, so can't say anything in that context but I tend to pay attention to top tube length and one is about 56 and tt bike is about 55.

my fixxie is a 58 (in standard seattube sizing) and it is too big. I am 6'.
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Postby helmut » Tue Oct 21, 2008 6:08 am

i measured myself and im 5'4'' (i swear i was taller than that!!!) ... ive got a 50cm frame :)

i dont really have anything to contribute cos its my first road bike, though i got it secondhand, i bought it from my lbs and they made sure that it was the correct fit before i rode out on it.... and yea, everythings pretty comfortable.
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Postby fredrikw » Tue Oct 21, 2008 6:45 am

I'm 171cm, have a leg length of about 79cm
- road bike: 50cm with a 52.5cm toptube length (+120mm stem)
- MTB: 16" with a 57cm toptube length (+100mm stem)
- CX: 51cm with a 52.2cm toptube length (+100mm stem, going to switch to a 90mm)
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Postby Man On Bike. » Tue Oct 21, 2008 5:24 pm

the crazyest vegan wrote:is the bike your on about the one in your picture? i think the seatpost look's good
Nope, it's the 60cm one in the picture. Now cracked. RIP :(
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Postby bob_summers » Wed Oct 22, 2008 5:25 am

a smaller frame for positional advantages? Smaller frames just give me backache!
Try a frame in the right size, horizontal top tube, no more than a fistful of seatpin showing. Look for a pic of Merckx for a good illustration!
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Postby JohnBarleycorn » Wed Oct 22, 2008 7:07 am

bob_summers wrote:a smaller frame for positional advantages? Smaller frames just give me backache!
Try a frame in the right size, horizontal top tube, no more than a fistful of seatpin showing. Look for a pic of Merckx for a good illustration!


Good advice !

Frame size is often dictated by fashion, rather than practicalities. And if anything, top tube length is more important than seat tube length.

All my frames are 54com, or thereabouts. I am 5ft 10in.

My top tubes are usually 54cm too.
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Postby the crazyest vegan » Wed Oct 22, 2008 8:15 am

my thinking is that a smaller frame is lighter and more aero and according to some weird calculation formula i found on the interweb my ideal frame size is 47 although i have no idea what that mean's as it didnt say top tube length or anything =P

i plan on getting this frame with a 50cm top tube

http://www.planet-x-warehouse.co.uk/ind ... ge_id=1049

in white of course :D
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Postby fredrikw » Wed Oct 22, 2008 8:32 am

5'7" is about my length I think. Are you sure about the 50cm top tube? Are you getting a stem that's 3cm longer than the one you have now? If not, any possible aero advantage will be canceled out by the fact that a shorter overall length means a more upright position on the bike...
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Postby bob_summers » Wed Oct 22, 2008 9:41 am

yeah, bear in mind that something like 90% of drag is created by the rider. any advantage gained with a too-small frame will be more than cancelled out by your new position :shock:
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Postby the crazyest vegan » Wed Oct 22, 2008 2:06 pm

but then again as it will be a racing bike shouldnt your position be more compact??

Edit:
i have a 30" inside leg btw
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Postby littlepurplegoth » Wed Oct 22, 2008 2:23 pm

Urgh - have to work in mixed heights here.

I'm 158cm tall, and have a 15" frame (and its only *just* small enough...). It doesn't get ridden enough....
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Postby fredrikw » Wed Oct 22, 2008 2:39 pm

the crazyest vegan wrote:but then again as it will be a racing bike shouldnt your position be more compact??

how can you decrease the overall length of the bike without you having to either sit more upright or hunching your back? 3cm is a major decrease in length, and if you don't compensate this with a 3cm longer stem you'll have a vastly different position on the bike. if there's one thing that separates racers from "ordinary" cyclists is that their bikes tend to be longer in total (with extraordinary long stems) and silly saddle-handlebar drops :)

don't think so much about getting the smallest frame you can, look at how you sit on the bike and what measurements you want to keep and what you want/need to change. do you need a longer or a shorter bike? do you need to increase och decrease the saddle-handlebar drop? etc.
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