Tyre Width

[Chopper]

So I pulled the trigger this morning on a 2016 Defy 2 Disc which was on sale and too good an offer to refuse. I'll be using this to commute the 25km to work and at times out for a quick Sunday ride before the kids wake up. I'm looking at getting wider, more puncture proof tires - my question is, how can I tell what size I can go up to?

There are currently 700 x 25 tires on it and I'd like to go up to 700 x 28 tires.

Cheers,
BK

[biker jk]

I believe the 25mm tyres which came with the bike are puncture resistant (Giant S-R4 Flat Guard). You could probably fit 30mm tyres if not wider but why bother if the existing 25mm tyres are puncture resistant?

[Chopper]

I believe the 25mm tyres which came with the bike are puncture resistant (Giant S-R4 Flat Guard). You could probably fit 30mm tyres if not wider but why bother if the existing 25mm tyres are puncture resistant?

I havent read in any of the specs or reviews that the tyres are flat gaurd, plus this is my first ever toad bike so I think I'd be a bit more confident on wider tyres.

[Thoglette]

how can I tell what size I can go up to?

Read this (Jan Heine)

but why bother if the existing 25mm tyres are puncture resistant?

Comfort and speed. Fewer flats and less risk from cracks & bumps.

[biker jk]

but why bother if the existing 25mm tyres are puncture resistant?

Comfort and speed. Fewer flats and less risk from cracks & bumps.

A wider tyre has lower rolling resistance at the same pressure. So you won't get both more comfort and speed.

[Chopper]

My priority would be comfort, not too fussed about speed.

[Chopper]

how can I tell what size I can go up to?

Read this (Jan Heine)

but why bother if the existing 25mm tyres are puncture resistant?

Comfort and speed. Fewer flats and less risk from cracks & bumps.

Cheers for the link Thoglette

[Thoglette]

A wider tyre has lower rolling resistance at the same pressure. So you won't get both more comfort and speed.

Actually you will. Lower pressure for the same (or more) speed, and more comfort.

You're welcome to be with the mainstream and not believe it. After all, it feels slower. To quote:

they said .."this cannot be"

..the push back was incredible

But hear all about it. CyclingTips Podcast, Episode 9: Rethinking road bike tire sizes and pressures

In the end, what we all need to realise is that smooth roads are still really rough

[madmacca]

but why bother if the existing 25mm tyres are puncture resistant?

Comfort and speed. Fewer flats and less risk from cracks & bumps.

A wider tyre has lower rolling resistance at the same pressure. So you won't get both more comfort and speed.

The whole point of running wider tyres is so that you can REDUCE the pressure, thus getting more speed AND more comfort.

[madmacca]

So I pulled the trigger this morning on a 2016 Defy 2 Disc which was on sale and too good an offer to refuse. I'll be using this to commute the 25km to work and at times out for a quick Sunday ride before the kids wake up. I'm looking at getting wider, more puncture proof tires - my question is, how can I tell what size I can go up to?

There are currently 700 x 25 tires on it and I'd like to go up to 700 x 28 tires.

Cheers,
BK

A disc brake endurance bike such as the Defy should be able to comfortably handle 700 x 28. It will probably handle 700 x 30, although it will depend somewhat on the tyre brand (some are notorious for being bigger than spec), and also the width of the rim you are running them on.

How can you tell? Take a look at the amount of clearance you have at the fork and frame with your existing tyres.

[biker jk]

Comfort and speed. Fewer flats and less risk from cracks & bumps.

A wider tyre has lower rolling resistance at the same pressure. So you won't get both more comfort and speed.

The whole point of running wider tyres is so that you can REDUCE the pressure, thus getting more speed AND more comfort.

The wider tyre at the same pressure will have lower rolling resistance. But if you lower the pressure of the wider tyre for better comfort, rolling resistance will rise.

So in the tests conducted for the Continental GP4000 II, rolling resistance for the 25mm version is 12.9 watts at 100psi. This compares with 13.1 watts for the 23mm version at 100psi. But drop the pressure of the 25mm tyre to 80psi and rolling resistance rises to 13.7 watts.

http://www.bicyclerollingresistance.com ... i-23-25-28

[Thoglette]

So in the tests conducted for the Continental GP4000 II,

Another test using a now thoroughly discredited test method (it's been a decade).

[Xplora]

Run the 25s at 80psi, sorted. You don't need new tyres. If you wanted more comfort, a road bike isn't the right tool for that job.

[li2099]

Watching Durianrider on Youtube, he has 2015 Defy(same shape different paint job) and he's running 30mm Victorias.
You should be able to fit 30mm with a very comfortable tyre pressure.