ChillDilettante

Old forum post have conflicting answers. Wanting to get an even more comfortable ride by switching to 28mm tubeless (thinking Conti GP 5000) from 25mm contis w tubes. Will it work?

HTupolev

If you have the bicycle, you're in a far better position than any of us to check if the clearances are adequate. A 28mm tire is going to add around 1.5mm to either side and 3mm above, compared with an otherwise-similar 25mm tire.

Keep in mind also that there's variance between tires. For example, a 28mm GP5000 might be similar in size to a 25mm that runs very large like a GP4000SII. It's also good to keep a few extra millimeters for safety.

ChillDilettante

Thanks for that. It looks like the 3mm above may not quite work in the rear. Maybe 28mm on the front, 25 back? I realize that wouldn't be optimally aero, but for comfort?

cxwrench

As HTupolev posted 'it depends'. Mainly on which brakes you have. If you post that info and maybe some photos you'll have to wait for someone with that exact combination to reply. Why don't you just try it?

ChillDilettante

Thanks cxwrench. Ultegra brakes.

Front

Rear

msu2001la

An easy way to measure the gap on the existing tires is to see which size allen hex key you can slide in there.

msu2001la

If my frame limited the rear size more than the front, this is exactly what I'd do.

Iride01 

You do realize that lever on the brakes where the cable attaches is to open them up more when removing the wheel don't you?

And to find out what the maximum spread you can have on that brake, you simply need to loosen the pinch bolt so they can spread open to their maximum amount. Then you'll be able to guess yourself what will and won't work.

However width of the brakes usually wasn't the issue of whether a wider tire would fit for me. It was usually the diameter of the wheel. Diameter of the entire wheel increases with the width of the tire. So it either rubbed the seat tube or the center of the brake caliper arms.

biker128pedal

How wide do the current tires measure and what is the inside width of your rim? I had a 2015 or so Madone and 28mm did not fit front or rear. A 25mm fit the rear but was too close to the fork bridge on the front.

GP5000 Tube type width
Conti 5000 25 mm 85 & 67 psi 27.4 mm 19 mm Rim grew to 30 after 3000 mile
Conti 5000 28 mm 87 psi 29.0 mm 19 mm Rim
Conti 5000 28 mm 74 psi 28.8 mm 19 mm Rim
Conti 5000 28 mm 64 psi 28.7 mm 19 mm Rim

Bah Humbug

Also note tires have different shapes - the GP4K was much taller and narrower than the GP5K at the same nominal size. You could probably fit a bigger GP5K into your brakes.

More comfort, less aero.

SkepticalOne

My 2016 domane frame did not clear a 28mm GP4K in the rear.

NJgreyhead

I have a similar 2013 endurance bike, the Spesh Roubaix, which came with 25mms.
I decided to try Plus 1, and found the Maxxis Re-Fuse 28s clear the rim brakes etc, no problem.
I ran Spesh Espoir 30s for a bit, and they cleared the stays, etc, but they just brushed the underside of the rear brake spring. With my hearing, it took a while for me to notice the tick-tick-tick.
I'm guessing you could roll with 28s.

eduskator

Probably not, and if it fits, it may be too tight around the frame and you risk damaging something if a rock or a debris gets between.