Road bike gravel capability

[Jolyon2002]

Hi,

I have a giant defy advanced 3 with 40mm deep SLR1 wheels. The frame has a lot of clearance and the bike is mainly a winter bike atm. What size tyre would be recommended for a bike like this and how capable would this be for gravel? I have a CX mtb so I don't want it for serious things. Any contributions welcome

[CampagYOLO]

That depends entirely on your local conditions. Well maintained gravel like the New Forest would be fine on 33-35mm tyres and your Defy.
Bashing over rocks and tree roots on singletrack will want much bigger tyres.

Round where I live there's some nice stretches of gravel but they're connected with much more technical singletrack so I prefer 650b wheels and 2.2" tyres. King Alfred's Way is a good example of the local conditions.

[Jolyon2002]

That depends entirely on your local conditions. Well maintained gravel like the New Forest would be fine on 33-35mm tyres and your Defy.
Bashing over rocks and tree roots on singletrack will want much bigger tyres.

Round where I live there's some nice stretches of gravel but they're connected with much more technical singletrack so I prefer 650b wheels and 2.2" tyres. King Alfred's Way is a good example of the local conditions.

I live Cambridgeshire area so nothing very technical. For single track etc I'd use my mtb. Do you think 40mm feel carbon wheels would be happy enough for some something like that?

[CampagYOLO]

If it's nothing too technical then the biggest tyres you can safely fit and at not too high a pressure should be fine. Main concern may be the nicks and scratches the wheels may pick up from the gravel.

Some gravel racers such as Ted King have used Endurance bikes such as the Synapse as it is a faster set up than a proper gravel bike on conditions that aren't too demanding.

[yinzerniner]

As always, start with the terrain then move backwards. Depending on your terrain you can choose the tire tread and construction type, then calculate actual tire size and pressure based off your weight using any/all of the online calculators from enve, zipp, silca, etc. From there see if calculated tire size will fit in the choke points of your frame and fork.

General rules of thumb tho:
-For general road riding 4mm clearance around the entire front tire, and 3mm clearance on the rear tire is adequate as you're unlikey to get any road debris larger than that stuck to your slick or semi-slick tires.
-For moderate gravel riding ~6mm front and ~5mm rear should be OK.
-If you're doing single track and or muddy conditions (ie close to MTB conditions) 8mm front and rear is the min suggested by most frame and tire manufacturers. This is for larger debris and especially mud.

[Marin]

You can ride gravel on 28s just fine. Tubeless helps a lot

[BenSiskri]

Most modern road bikes are pretty capable, and light gravel should be no problem; I had a rim brake Domane, and could fit 32mm GravelKing SK tyres in it. In winter I'd often use 30mm Schwalbe CX Pro. My current 'winter/ gravel' hack, is a disc brake Domane AL4, and I've got 31mm Vittoria Terreno Dry fitted, tubeless.