Theoretical watts lost due to too wide a tire
Moderator: robbosmans
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Thanks, I'll have to see if I can find some of these. I'm surprised the difference is so small.
It depends what your rim width is. If your rim is 25-26mm and you go from 25 to 28mm tire you will loose in the 4-5W if your rim is wider you will be in the 1-2W range (data for reasonable speed around 30 or 40kph).
That’s one of the reasons Canyon send their bikes to Tour with 23 front 25 rear tires (and now with wider rims, with 25-28 combo).
That’s one of the reasons Canyon send their bikes to Tour with 23 front 25 rear tires (and now with wider rims, with 25-28 combo).
Let's say the wheel is 50 deep and 25mm wide, you put on a 28c tire that measures 28-29c.C36 wrote: ↑Sat Aug 20, 2022 4:45 pmIt depends what your rim width is. If your rim is 25-26mm and you go from 25 to 28mm tire you will loose in the 4-5W if your rim is wider you will be in the 1-2W range (data for reasonable speed around 30 or 40kph).
That’s one of the reasons Canyon send their bikes to Tour with 23 front 25 rear tires (and now with wider rims, with 25-28 combo).
Wondering if there are tests with data and graphs? Where is the 4-5w number coming from?
I know it makes a difference I'm just curious how much.
Not nothing, at least according to the below:
https://www.hambini.com/testing-to-find ... le-wheels/
(but that's 23 to 25, but still...)
https://www.hambini.com/testing-to-find ... le-wheels/
(but that's 23 to 25, but still...)
18w at 50kph if I'm reading that right? I think the old c60 was 24-25mm wide and the gp4000 ran a size large...Singular wrote: ↑Sat Aug 20, 2022 5:13 pmNot nothing, at least according to the below:
https://www.hambini.com/testing-to-find ... le-wheels/
(but that's 23 to 25, but still...)
Correct - if anything, the negative effect of a lightbuld-shape tyre is apparent in this test. The wider Enves fare significantly better in this instance.spartacus wrote: ↑Sat Aug 20, 2022 5:23 pm18w at 50kph if I'm reading that right? I think the old c60 was 24-25mm wide and the gp4000 ran a size large...Singular wrote: ↑Sat Aug 20, 2022 5:13 pmNot nothing, at least according to the below:
https://www.hambini.com/testing-to-find ... le-wheels/
(but that's 23 to 25, but still...)
That was from a road test done by a continental team on a open velodrome 2 or 3 years ago. They also tested at higher speed but I lost trace of the results.spartacus wrote: Wondering if there are tests with data and graphs? Where is the 4-5w number coming from?
Supersix Evo2HM - aero-stiff 5970g / light 5690g
It really depends on the wheel you're putting it on. And that doesn't just mean simple width/depth measurements, as the location of maximum width on the rim is really important - just having a number which says how wide a wheel is at either the brake track or an indeterminant point further down doesn't give you the whole answer as the location of this maximum width.
You should also consider the speeds that you're travelling - if you're being quoted 1w at 45kph then this is very little (difference in speed of 0.045kph), whereas 1w at 30kph is double this from a speed perspective (0.1kph).
It's one of those unfortunate things where there is no blanket answer, and you have to do the testing on the exact wheel and tyre model you're comparing to understand the impact. Some wheels are specifically designed to accommodate a range of tyre sizes, others less so.
You should also consider the speeds that you're travelling - if you're being quoted 1w at 45kph then this is very little (difference in speed of 0.045kph), whereas 1w at 30kph is double this from a speed perspective (0.1kph).
It's one of those unfortunate things where there is no blanket answer, and you have to do the testing on the exact wheel and tyre model you're comparing to understand the impact. Some wheels are specifically designed to accommodate a range of tyre sizes, others less so.
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Thanks, this makes sense, I was just hoping there were tests done where someone intentionally tested tires that are wider than recommended (3-4mm wider than the wheel) on various rims but so far the hambini one is the only one I've seen, and that was kind of accidental due to the gp4000 running large and being inflated to high psi.xav wrote: ↑Mon Aug 22, 2022 11:36 amIt really depends on the wheel you're putting it on. And that doesn't just mean simple width/depth measurements, as the location of maximum width on the rim is really important - just having a number which says how wide a wheel is at either the brake track or an indeterminant point further down doesn't give you the whole answer as the location of this maximum width.
You should also consider the speeds that you're travelling - if you're being quoted 1w at 45kph then this is very little (difference in speed of 0.045kph), whereas 1w at 30kph is double this from a speed perspective (0.1kph).
It's one of those unfortunate things where there is no blanket answer, and you have to do the testing on the exact wheel and tyre model you're comparing to understand the impact. Some wheels are specifically designed to accommodate a range of tyre sizes, others less so.
In this blog Josh from Silca is sharing some data from an old Zipp 404 with a 23mm GP4000 and a 25mm GP4000 at different pressure levels (widths).
https://silca.cc/blogs/silca/part-5-tir ... rodynamics
https://silca.cc/blogs/silca/part-5-tir ... rodynamics
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