urbanknight

I built up some lightweight road wheels (for my road bike) a couple of years ago but ended up sticking with the deeper wheels after all. The light wheels have been sitting around since then and I realized I could put them to use on my gravel bike. The bike serves two functions: (1) offroad riding on fire roads and light singletrack with 42mm wide knobby tires, and (2) road riding when it's dark and/or raining on 35mm wide slicks. I'm trying to decide which wheels to use for which purpose. Obviously my "gravel" rides are for fun and usually with some buddies, and my rainy or dark road rides are usually solo and more about getting some mileage in.

Wheelset 1: Stock Giant PX-2, 24mm IW, 24mm depth, alloy rim with 24 double butted spokes, ~2,000 grams

Wheelset 2: Mavic Open Pro Carbon rims, 21mm IW, 32mm depth, carbon rim with 28 aero spokes, ~ 1,400 grams

The inclination is to have more fun with the lighter pair on the offroad rides, but they are also noticeably narrower than the stock wheels. What do you think?

Koyote

According to the physics, the lighter wheels won't be much faster than the heavier wheels. (Just getting that out of the way as a public service - hopefully we can now move on.)

The Open Pro rims are narrower at 21mm ID, but I have been happily running 42mm nominal width (measure out at about 44mm, though) tires on 19.5mm ID rims for almost five years now. If I were you, that's what I'd use for riding with friends. Then use the boat anchor wheelset for your solo training rides.

mstateglfr 

I would ride the lighter wheelset all day every day. There is just no downside.
I used 25mm external 20mm internal rims for my gravel bike for 4.5 years and all tires were 42-44mm actual widths. I never thought during a ride- 'man, I wish my wheels were 4mm internally wider!' because the wheels and tires felt and rode fine.

You save 1.3 pounds with the carbon wheels- thats significant. Yeah wheel weight really wont slow you down on flat roads, but this is a hobby, having fun is a big reason why people ride, and wheels that accelerate faster after slowing down on turns or feel faster when riding up a hill are absolutely worth using.
This is especially true for singletrack or other twisty riding where you are constantly braking, turning, and accelerating. Maybe you only save 5 seconds over the span of a ride with the lighter wheels, but if they feel more fun while riding, thats an easy decision.

urbanknight

Agreed, but the placebo effect is still valid to me.

Since I'm running slicks for the streets and knobbies for the trails, and I'm not going to swap tires regularly, I'll have to dedicate one set of wheels for each purpose. Otherwise I would definitely just run the lighter set every time and let the stock wheels sit next to the road bike's stock wheels.

Steve B.

Many folks who ride gravel bikes do exactly this. A wheelset with 28-32 or whatever slicks, maybe a cassette appropriate to the road conditions and hills. Then a 2nd wheelset with gravel tires and maybe a different cassette (or not) for hillier conditions. This is how I have my C-Dale Topstone setup. It’s a great road bike when it’s not my gravel bike.

Koyote

Yeah, swapping wheels back and forth is tiresome. That alone is reason enough to have two wheelsets for a heavily-ridden bike.

urbanknight

Well I think that settles it unless someone knows of a reason one wouldn't want to run Open Pro Carbon rims off road. Some stores list them for road and time trial while others list them for road and gravel. Mavic's website has a page for the product, but with absolutely no information.

tFUnK

Between those two, my inclination would be to run the wider tires on the wider rim. That said, the narrower rim is still pretty wide. With that big of a difference in weight between the sets, if it were me I'd only use the lighter set and swap tires when desired (assuming you'd do this no more than a few times a year).