spiroX

Hi,

I have a gravel bike and have been wanting to get road wheelset to be a bit faster on the road. I got the money but now I am having second thoughts as I don't know how faster I would be?
Right now I have WTB isym 23 wheels (with cheap formula hubs) with WTB 650x47 Horizon tires. The tires are more road+ tires than gravel tires and are smooth on the center with no knobs. I was thinking of getting 700c wheels with road 700x32 tires (for some comfort on day long rides and some light gravel).
I do not race, and I am still working on my fitness (as my work and family time allows). My average watts (according to Strava) is 210W for an 1h ride and some 180W for an 3h ride after which I feel pretty tired (although not totally exhausted).
With new wheels and tires I could loose some 500-600g of weight and should have better aerodynamics and lower rolling resistance.
My question is will all those 3 things make a significant difference? Only one of those might not, but with 3 combined will it make a difference?

Thanks.

jpescatore

You might first try some good, more narrow 650 road tires - that is where you will see most reduction in rolling resistance on pavement. At below racing speeds, bigger wheels aren't necessarily faster - lots of mythology out there on that.

Similarly, at non-racing speeds, I don't think the aerodynamics will be any gain at all for new wheels, so there is only the weight savings - new wheels would be a lot of money to spend for 500kg savings.

Another thing to check: while many bikes will take either 650 or 700c wheels, the frame geometry may be such that the larger 700c wheels will cause your feet to overlap the front wheel too much. Some amount of toe overlap isn't a big deal but depends on the geometry and your crank length if it will be a problem for you.

I have a Jamis gravel bike with 700C wheels that are strong but heavy and 40mm gravel/knobby tires. For pure road rides, I switch to 32mm road tires. Swapping wheels would be easier, and I could go with lighter wheels but I could also stand to lose a pound or 10 from my body! So, I just switch tires.

WhyFi

Will it make a noticeable difference? Yes, very much so, particularly in terms of perception - it will certainly feel more light and lively. It will have an effect on metrics, too, but without a real power meter, you might be hard-pressed to point at solid evidence of gains, particularly on solo rides.

I would actually encourage you to go a little skinnier, though - 28 or 30mm. Unless you're really heavy or your light gravel is much gnarlier than mine, 28 or 30 will do just fine and will give you more of the light, snappy feel that you don't get with the larger, heavier wheels/tires. YMMV, but at 185-200lbs, I'm comfortable running (tubeless) 28/30mm tires at ~65-70psi. A personal favorite tire, if you're looking at mostly pavement but some light gravel, is the Schwalbe G-One Speed (formerly known as the S-One, if you're looking for reviews online).

ThermionicScott 

Those tires are slick, but there are lighter/faster options in that general size. You could knock a little under 100g off each tire by going to Compass/Rene Herse in the same size (Switchback Hill), and a bit more than 100g by sizing down to 42mm (Babyshoe Pass). And that's without considering the extralight versions.

spiroX

@jpescatore
My bike can accomodate up to 700x42. It used to come with 700x35 until they switched to 650x47. I myself could loose 2-3kg (4-6lbs) but not more than that, it would make me too skinny and all 2 of my abs would show I am working on my fitness regardless of this upgrade and I will probably loose a few pounds, but that would mean that with the upgrade my bike+rider would be 2-3kg lighter
@WhyFi
I was thinking of getting Pirelli Cinturato Velo in 32 as those (according to the reviews) seem to have very good puncture resistance and not too bad of a rolling resistance. I also like to do day long rides so that little extra comfort helps. Especially since I'm used to comfort on 47 tires.
@ThermionicScott
I was thinking of getting smaller tires, but I was afraid of my bike being too low. I have 165mm crankarms, but I do like to pedal in corners and don't want pedal strike.

jpescatore

I use 32mm on my road bike - unless you are a racer, lots of science showing there is minimal (if any) gain in speed going smaller unless you are always riding on a dynamometer! I run Continental GP 5000s - so far no flats and they tested low in rolling resistance. Not sure how much lower your pedals will be going from those 47s to 32s, you'll probably just have to try it.

rivers

I run 32mm pirelli cinturatos on my winter bike. They're a decent tyre. Rolling resistance isn't as low as something like the GP5000s (I'm still running 4000s on my summer bike), but it isn't bad, especially for a thick tyre. I don't have any complaints about punctures, and I'm running them tubeless.

bruce19

FWIW I've gone to Mavic USTs on both my road bikes. Faster, lighter, smoother and more comfortable. And, that's with 25s.

WhyFi

You sound like a relatively light person. Are you going to be running tubeless, also?

Run what you want to run, but if the goal is to have something markedly lighter and more spirited than your chunky wheels/tires, while still being robust enough for light off-road, then you're leaving a lot on the table with your selection. Again, I'm getting 2,500-3,000 miles out of 28-30mm rear tires at ~190lbs on some horrible roads and with the occasional gravel.

spiroX

OK, I managed to borrow some wheels to put on my bike and do a direct comparison.
Couple of things to notice:
- The wheels are almost the same as the ones I was looking at. The difference is in the hub and the tires. They are not dt Swiss hubs and the tires are some Specialized turbo pro 28mm road tires that came with the friends Roubaix.
- I wasn't my top when I did this, I might be coming with a cold.
- I had head wind about 1/3 of the way up because why not! It wasn't very strong but I could feel it slowing me.
- I don't have a power meter so I rode against my heart rate. If it would go below 168 I would accelerate and if it went higher decelerate. Not the best way but that's what I did when I did a PR on this uphill.
- Tires were at 80-85psi or around 6bar. Not tubeless.

And the results? My time on an 5% ~8.5km uphill was exactly the same at 37min! (give or take a few seconds) as with 650b 47 tires. I was very surprised!

Observations :
- The bike felt very different, it felt quicker and more maneuverable.
- It actually didn't feel more uncomfortable, in fact the road felt smoother! The potholes and speed bumps though were a lot more noticeable.
- Braking is noticeably worse. I had to brake sooner on downhill.
- When going back down I did a PR without even trying. That was VERY surprising as I didn't even pedal all the time. It might have had something to do with wind as on downhill it was in my back.

Conclusion:
With these wheels/tires I am probably a bit faster. I would say 3-5% judging by the headwind and the fact that I didn't feel my best. I definitely like the feel of them, but will I buy them? Actually I found those same wheels for 200€ with rotors which is a great deal so I will buy them Although I am not that faster they do feel better on the road and when I'm fully recovered if I can be 5% faster on uphills that is a BIG increase. Maybe not worth 5-600€ or more, but definitely worth 200! If I hadn't found this deal though I probably wouldn't switch. Or at least not yet, but might have waited for my current tires to wear out completely and then buy new wheels + tires.

Thanks for the help, maybe this will help other people looking to make the switch.