26mm vs 28mm Tyres and Road vibrations

Quick One…

Took my SL7 out for a gran fondo over the weekend. Currently running my Specialized Turbo 26" tires at 80 psi. Felt a lot of road vibration from shitty roads, thinking about moving to 28" Spez Turbo Cottons / Vittoria Corsa G2.0 and run them at 65 psi.

Now a friend has 28" tires and says he still feels quite a lot of road vibration, but he also has 10kg on me. So not sure if the higher pressure would effect this.

Would moving to 28" @ 65 psi allow me to notice a difference in removing some of that road vibration…as the Roval CL wheels are designed around a 26" I’m reluctant to go to 28"

Yes, you should see less road vibration. It won’t eliminate it though. Yes, his higher weight (and thus tire pressure) would probably mean that he’s feeling more vibration.

The CL’s being designed around 26mm vs 28mm won’t really affect the vibration aspect but will have a larger impact on aero. So you’ll probably see lower rolling resistance and a more comfortable ride but you may be sacrificing some of the aero benefits. But those wheels will have no issues with mounting 28s on them.

This what I am worried about lol #marginalgains

I edited your title to replace the " marks with mm (millimeters) as the proper notation for this measurement. The " double quote is the symbol used for Imperial Inch measurements.


Could you moderate ebay too please? Not sure whos buying 58 inch trek emondas


:rofl: If only… I know units and general labeling in posts can be TERRIBLE.

For instance, years ago… my brother actually made a small business of searching EBAY cell phone listings done poorly, that would not show up with a “proper” search or were in the wrong category. He did misspelled names and such, watched the auctions on those and effectively “stole” them for super low bids because people simply didn’t see them.

It’s a very real issue and can lead to bad sales for sure :stuck_out_tongue:


It’s also pretty bike dependent. Straight up performance bikes (like the SL7) aren’t really designed for comfort. 28mm tyres will help but I imagine the gain would be marginal. It all comes down to what you want the bike to be good at - there is always a compromise that has to be made.

I thought I was going to be the first pedant to reply “technically all your tyres are 28” (700c)!

To answer the question, I can definitely feel the difference between 25 and 28s, but if you can fit 32s you’ll rarely regret it if not racing!


There is a middle ground between those two…you could like drop the psi on your current tires down to 72-75psi and soften the ride a bit.

Thought about dropping the psi, I was going off the Roval suggestions for my weight (70kg / 155lbs)

But you reckon dropping the psi a bit would work out ok ? Dropped it to 75 psi (lets see how that will work tomorrow)

The good thing about testing lower psi is that it is pretty risk-free…keep dropping the pressure until you hit a point where you don’t like how it feels.

based on that chart, I think you can easily start at 75psi and give that a whirl. 130-160 w/ 26mm = 78 psi…you are a lower weight than that, so 75 is a good test point.

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Just for comparison sake…

I weight ~183lb (so the upper end of the dark black range) and run 30mm Corsa Controls on my bike at ~59psi. Any my wheels have a 1mm narrower internal width so theoretically your wheels would allow you to run ever so slightly lower pressure than me.

I’ve loved the smooth ride of them. They do feel just a hair squirrely on really hard cornering so I was planning on going narrower when races picked back up. But then they never did so I kept them.


I run 28m conti gp 5000 on my CL50s on an sl6. Only change I have made to the stock build and it’s been such a difference maker for me. I would try it for sure but be warned, once you go up in size you won’t want to go back down. Ever. Seriously when I got my tarmac something felt off. Changed to 28s and it became absolutely perfect for me.

interesting…my turbo bike is TCR running 25mm tyres, so i have gone up a mm with the SL7 but with the Rapides being built around the 26mm tyre, I have spoke to Roval they say for speed and aero stick with 26mm but for that bit of comfort go up to 28s.

I am curious about trying the 28s for sure, my mate has the same set up as you 28s GP5000 SL6, he enjoys them. I just wish GP5000 had the tan wall, instead of that limited edition set that only come in 25s boooo.

Dude! Just try it! I’m not really a fan of tan sidewalls but I did feel left out when they did them in 25 only :laughing:

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