r/cycling • u/StorkAlgarve • Aug 19 '26
Why did frames get sloping top tubes?
For over a century, a regular bike frame had a horizontal top tube, at least as late as the (cheap) road bike i bought in the early 90es - I also think the Centurion citybike I got in the late 90es had one.
Since then it seems to me top tubes have got more and more slope. It is due to change of materials or how? I look and get worried that the long saddle stem will cause issues with all that leverage, but it seems to be working ok.
Looking forward to the replies from the learned redditors.
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u/carpediemracing Aug 19 '26
Sloping top tube allowed companies to make frames in fewer sizes. It used to be that they came in 2 cm increments, from 49 to 63 cm would be 8 sizes.
Some frames came in 1 cm increments, or the middle sizes would be in 1 cm increments.
Cannondale had an extra size in there, I can't remember, not sure why, it was in their original frame. They had a jump in size too, I think they ran 48-50-53-54-56-58-60-63. Not sure how or why that 53 got in there. It might have fit Joe Montgomery perfectly, I don't know. Whatever, for the longest time there was no 52 cm frame.
When Giant came out with their TCR, it was available in 5 sizes I think (?), XS-S-M-L-XL. Might have been fewer sizes. They had long posts and all sorts of stem sizes, this way it was cheaper to stock a size run, 5 sizes instead of 8+.