Yep - I’ll happily roll along in comfort knowing that I’m just as fast!

Thanks man - Most the roads around here I would say certainly would be considered bumpy!

Thanks Seth - doesn't seem to be much of a reason not to switch to be honest. I'm glad that I went through and tested them just to prove it to myself!

This is an excellent idea - I could totally see this being the norm at some point in the future.

I did not and I think that’s where some of the extra weight came from - apart from the different types of tires. I started with similar amounts when I originally installed the 28’s about 8 months ago, then added a few mls periodically overtime.

@@TBBCycling Easiest way to solve this would be to weigh the tyres each

I could certainly do that, but tbh they’re already mounted, so I’m not really interested in taking them off again. I’m happy knowing that the new setup is lighter, doesn’t really bother me where that weight saving is coming from specifically.

Yep - I’m only about 62kg. I’ve never actually used the Zipp tire pressure calculator - looks like they recommend quite a bit less than Silca, which is interesting. I actually think the pressure is probably more important than the width, but that’s a test for another day!

I’ve never looked into tire inserts actually - what is their purpose?

Inserts are just to ride on a flat tire. Totally unnecessary unless you're a pro riding with a support team.

Measuring tire height/diameter is something that I didn’t do, so you could certainly be on to something!

Perhaps, but only if you blindly believe the marketing - I like to check these things for myself and now I know. There's also maybe not that big of a difference in rolling resistance than you may think. I don't have access to the 'member only' data from Bicycle Rolling Resistance, but at 90psi they measure the AS 28mm CRR=0.0033, which is less than the S 32mm at 44psi of CRR=0.00384. Obviously you'd want to compare similar psi, but the difference may not be as far off as you would expect. A BRR member may be able to let us know.

​@@TBBCycling You never ride different width tyres at same pressure for a shitload of reasons. But your pressure difference is way off any reasonable bounds. Under same conditions the correct diff between 28mm and 32mm is less than 20psi. Check Silka tyre pressure calculator. Your measurement is useless.

If you read my comment you know that the only reason I referenced those pressures was because I am not a member at BRR, so I don’t have access to all of their measurements - this was just to show that the rolling resistance difference probably isn’t as large as one would expect. These aren’t my measurements and I certainly wouldn’t recommend riding at those pressures. If you’re a BRR member and have useful measurements please do share.

Good advice! I plan to test them out today, so I’ll let you know how I make out. I think I’m making a bigger deal than necessary about them - it’s really only .25-ish long.

This isn’t a sponsored video or anything, I was just switching tires and wanted to see which was faster. You’re welcome to send me a set of 32mm GP5k AS to donate to the cause!😄 Everyone keeps saying that thinner tires are faster and I know the theory - they should be, but I have yet to see it happen in anyone’s real life testing (even with the same tire type). Maybe most real life roads are bad enough to make up the difference? Or we’re not going fast enough for the better aerodynamics to matter? Either way, it was a good test for me knowing that the faster tire was still faster for me, even in the wider width.

@@TBBCycling i just told y, the wider tires have better rolling resisitance and you did more power.

Wrong

@@sevenrats right ▶️👍

Thanks Luke - I'll likely dig into the math at some point - I was a physics major, so this stuff is really interesting to me. It's so counterintuitive for the wider tires to be faster, but this seems to be consistent across all the reviews/tests I've seen. I'm curious how smooth the road has to be for the skinnier tires to be faster? The roads around me tend to be fairly rough. Tire pressure I think has a huge effect on this also. How fast do you have to be riding until aerodynamics really matter? Zipp says that the 303S was designed for 28mm tires for optimal aerodynamic efficiency, but didn't seem to matter in this case for me. Weight was interesting because the wider 32's were actually lighter in this case, so that throws the calculation off a little bit. Anyway - I'm glad that I did the test and until I can prove it to myself that the skinnier tires are faster in the real world I'm sticking with the 32's!

I think wider tires being perceived as faster is a placebo effect. It helps to sell drugs and it helps to sell cycling equipment. If you look at the question at hand scientifically, there is not any definitive evidence that wider rims are faster or slower, at least I can't find any. We even might even need serious blind studies in real world conditions employing sophisticated measuring equipment (off-the-shelf power meters might not suffice) to address such small differences. Using just power data won't suffice because we cyclist tend to change posture if we think we are going faster and that messes with aerodynamics. And how do we even do blind studies if the tire is in front of cyclist nose? Moreover, we all know there is no financial incentive for doing this. I am not saying that those youtube tests are totally worthless. But I am leaning more into theory nevertheless. So I have come up with those "postulates": - rolling resistance on relatively smooth surface is small compared to aerodynamic drag (except on very steep climbs where rolling resistance is very small compared to dynamic component of gravitation) - difference in rolling resistance between narrow and slightly less narrow tire is extremely small - wheel with wider tire has significantly greater surface area - wheel with wider tire has less favorable thickness-to-chord ratio Based on that I would choose narrower tire-rim combo as a faster option. I am not 100% sure though, aerodynamics are very unpredictable.

The only reason why wider tires became the buzz is simple, a few decades they started to use carbon fiber composite instead of of metal alloy bike frames. They are to stiff for the comfort, Jess it’s good for smooth surfaces, not so much in other circumstances. So industry sought compliance in other way, dampeners and wider tires for the difference in stiffness. …

And rider comfort gives speed, in many of those tests

vibrational losses?

Could be! But if I can go the same speed (or faster) with more comfort and it’s safer (at least in my case with the hookless rims) then I’ll take that.

I was agree with that sentence until I swap my 28c to 32c. If that marketing bs, than I take that BS because it feels more comfortable and the brake are grippier, and could take some small section of smooth gravel easily.

@@laillosidgar +1 - after a couple of test rides I'll take the BS! Now I just have to figure out the best tire pressure for me.

You are safer with the 32 mm tires and lower pressure. Silca just released a video that addressed the problem about max tubeless pressures vs optimal pressure. And if your optimal pressure is higher than the rim limit, Josh Poertner says you need a wider tire. I got a new bike last summer and had a set of wheels built with hooks because I was concerned about the hookless issue and I didn’t want to run a tubeless setup on my road bike. 32 mm GP5000 with TPU tires is working great!

@@randallsmith7885 That's exacly what I was thinking. My recommended pressure was getting close enough to that hookless limit that I just didn't feel comfortable with it. Glad the new wheels are working out for you!!

Also, do multiple repeats of your tests in bunch of conditio🎉n and look overall ...

This was all just my informal testing, so certainly not a scientific study! You can make your own conclusions, but I’d seriously doubt that the extra 5 watts would make me 37s faster.

Whoa - while I very much appreciate your passion over my equipment choices - there’s no need to shout!! Seriously though - I’m guessing when you say “ITS PROVEN” you mean on a track - I don’t ride/race on a track and the roads around me are far from smooth. The surface being ridden makes a big difference in real world speed. So I will quite happily plod along on my 32’s in comfort knowing that I’m just as fast in most circumstances instead of rattling my teeth out on 19’s. Heck - I may even switch to 35’s at some point when my frame will take them!

Because track racers are riding on a well maintained and super smooth surface that won't be found outdoors...just saying.

Recently in 2023 the UK Track Racing team has been riding on 28mm tubeless tires. So check your « knowledge » maybe?

Very interesting!

You're just wrong. Multiple groups have tested different tire sizes.