Lyca

Hi All,

I have recently bought a new wheelset for my Pinarello Prince 2021 disc bike. Campagnolo bora wto 45 disc version. Currently I’m mounting some very basic, cheap wheels with the conti gp 5000 28c clincher.

With the new wheelset, I’d also like to have some good tyres. The idea is to switch to tubeless, still continental gp 5000, but I’m not sure about size.

clearance is not a problem, as I have a disc brake bike.

The new rim width is 19mm internal, 26mm external.
I’ve heard and read that a 28mm tubeless tyre would end up measuring 29-30mm, hence losing the aero benefits of the medium profile depth wheel (45). But 28mm would give more comfort..

I weigh 80kg and cycle in and around London, no races, just trining on flat and hills, surfaces tend to be normal in the area, but sometimes rough.

on the other hand, 25mm tyre would be more aero but provide less comfort..

what do people recommend? Any advice on this choice?

Thanks so much for your comments and help!

DaveSSS 

Try 28mm michelin tubeless. They will measure 29mm after they stretch out. Consult zipp pressure calculator and use what they suggest, but be sure your pump gauge is accurate - mine wasn't. Why so much concern about aerodynamics? You're not racing. At 62kg, I use 62/64 psi.

Lyca

thanks! Would the 25mm be more aero than the 28mm? This seems to be the big argument, with the 28mm being a bit too wide for the wheel’s aero profile..

thanks

WhyFi

Would the 25mm be more aero? Sure. Would you be able to notice it, either by the seat of your pants or on a stopwatch? Not likely.

Meanwhile, at your weight, you'd *definitely* notice the difference in running lower pressure on the 28s. Fatigue is very real - little bumps and jolts add up on long rides and feeling fresher is faster. Then there's the suspension losses of running higher pressure on real-world roads; smooth is fast - vibrations working their way up from the tarmac are robbing energy and letting supple, lower pressure tires deform around those bumps is more efficient.

At the end of the day, though - they're consumables, don't overthink it. IMO, the 28s would be better suited to you and your roads, but buy both, if you want - wear out the first set in a couple months and then try the others.

Sy Reene

Start off simply moving the 28mm GP5Ks you have already to the new wheelset and see how it goes. You want to go tubeless.. is this because you're flatting often? Just IMO, but I probably wouldn't consider TL for 25mm tires.

WhyFi

Why? Is this opinion borne of experience?

Sy Reene

Nope. Just enough stories about difficulty mounting TL 25s (see the lightbicycle reference guide), higher pressures sometimes challenging sealant abilities. I think OP is looking at recommended rear pressure of about 90psi if he opts for 25s.

WhyFi

Ah, yeah. You need to take all of that stuff with a grain of salt, looking at things like the experience of the user and the equipment being used. More often than not, it's a fault that lies with the user, so regurgitating their tales often does nothing but magnify non-issues. I've only run a couple sets of 25s, but they were no more difficult to mount than 28s or 30s - I think that small, brand-to-brand variations in bead diameter will have a bigger impact than tire size. Also, no issues with Orange Seal doing the job at 105psi.

Iride01 

Have you tried 25 mm tires of the same make and model as your 28 mm tires to find out if you can tell the difference? Or are you just imagining that you can tell the difference.

Different makes and model tires will give a difference in ride more so that width changes alone. But don't anyone interpret that to mean I think you'll have just as good a ride on a 18 mm tire than the same tire in the 28 mm version. But who knows, if your roads are smooth, you might not care.

tomato coupe

A few years ago 25 mm tires were considered "comfortable" road tires. They still are.