I'm confused about sizing.

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Gravity Aided

Legendary Member
Location
Land of Lincoln
Pretty much how I do it, but I just have horizontal top tube bicycles.
 

youngoldbloke

The older I get, the faster I used to be ...
It would really be helpful if there was some agreed standard way of measuring frames - virtual seat and top tube measurements should always be stated, as well as actual. I would also want to know the length of seat tube above the top tube, especially on a compact frame.
 

smutchin

Cat 6 Racer
Location
The Red Enclave
Horizontal. Just looked online and the picture shows more sloping.

If you think that's a horizontal top tube, remind me never to ask you to lay a patio for me. ;)

A size 52 frame sounds about right for your overall height, but it does also depend on the proportion of leg/torso length - I'm the same height as m'colleague but he tends to prefer a larger frame because he has longer legs; I prefer a smaller frame with a longer stem.
 

smutchin

Cat 6 Racer
Location
The Red Enclave
I just thought that as I get better and fitter my body might change but the bike wouldn't be able to adapt. Newbie mistake. Sorry.

It's not as daft as you might think - as you get fitter and stronger, and lose weight, you'll probably find you want to spend more time in the drops. You might even want to lower the handlebars, which will depend on having spacers under the stem.
 
OP
OP
cabbieman

cabbieman

Senior Member
Sounds the right size, why would you have issues in the future, are you still growing?

Funnily enough, I've been going to the doctors every month for my on going blood pressure checks and the last month has seen me lose 3.4 kgs but also gain 2cm in height . At this rate ill be a six footer at the end of the year.
 

smutchin

Cat 6 Racer
Location
The Red Enclave
The horizontal reply was off the top of my head. Didn't realise it sloped so much till I looked at the picture after

It's possible that the degree of slope varies between different frame sizes, and it will vary between different manufacturers - that's probably quite horizontal compared to, say, a Giant TCR but the slope will look more pronounced compared to a bike with a genuinely horizontal top tube.
 

boydj

Legendary Member
Location
Paisley
I gave up on seat tube measurements for sizing , everyone measure differently, i am more interested in top tube measurement . both my boardmans are listed as 51.5 and have a 54 top tube .

Agreed. The horizontal top tube measurement is the best for comparing different makes and for making sure you get the right size.
 

youngoldbloke

The older I get, the faster I used to be ...
If the only measurement given is centre to top there is no indication of the actual length of the tube below the top tube junction, and therefore the slope of the top tube is difficult to assess. I ride small frames, and this has implications for the amount of standover and the space within the frame triangle for bottle cages etc. Some modern frames have a lot of seat tube above the top tube junction.
 

Ajax Bay

Guru
Location
East Devon
Some modern frames have a lot of seat tube above the top tube junction.
But I don't think many seat tubes extend much beyond the point they would have 'reached' with a conventional horizontal top tube so the length of seat tube above the seat tube / top tube junction is really a function of how 'slopey' the top tube is. But I hadn't thought of your 'space in the triangle' point. Which make/model had you in mind which has a lot of seat tube above the top tube junction?
It would really be helpful if there was some agreed standard way of measuring frames
Agreed but we've had the centre to top and centre to centre anomaly for half a century (at least). The internet gives pretty good access to a proper 'dimensions' chart and most will show both ctc and ctc(virtual/horizontal) to inform the buyer's choice.
horizontal top tube measurement is the best for comparing different makes and for making sure you get the right size.
The(horizontal/virtual) top tube dimension (ctc) has become the most important one, with the advent in the last 20 years of increasingly long seatposts combined with sloping top tubes.
 
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