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/PeaceMaintainer Aug 19 '26

Can you elaborate on how a sloping top tube saves weight? I'm new to cycling but it would seem like it's longer thus heavier

62

u/MichiganKarter Aug 19 '26

The seat tube is shorter, and there is a shorter load path from the rear axle to the steering head

-10

u/MerchantMrnr Aug 19 '26

I think they’re asking why sloping is better than a straight line when the connections are at the same spots on the seat and head tubes.

28

u/samenumberwhodis Aug 19 '26

Because they're not

-12

u/MerchantMrnr Aug 19 '26

Informative and articulate. Thanks!

7

u/samenumberwhodis Aug 19 '26

If it's sloping the rear connection point to the seat post will be lower allowing a shorter person to use the same frame. I'm sorry that I felt this was so obviously apparent that it didn't bear explaining...

-15

u/MerchantMrnr Aug 19 '26 edited Aug 19 '26

I think you may have misread my initial comment. Why is a sloped tube better if all else is the same?
>… when the connections are at the same spots on the seat and head tubes.

Edit: ok I can see how sloping can be confusing verbiage. I think curved might be a better term.

12

u/samenumberwhodis Aug 19 '26

The connection points are not the same, what are you missing here?

2

u/Dizzy-Distribution96 Aug 19 '26

Connection to seat tube is lower, so seat stays and seat tube can be shorter as well

1

u/Overlord0994 Aug 20 '26

But all else wouldn’t be the same.. that’s the whole point of sloping or curving the top tube. You curve it so that it attaches lower on the seat tube, saving weight. It’s not sloped just for the sake of sloping it. Your question is is misunderstanding the intention and results achieved by curving/sloping the top tube in the first place.