Big difference between road bike and gravel bike with road tires?

I am on the hunt for a new bike, currently riding a 2003 Trek 5200 that has seen better days. I am interested in doing some gravel events in the future, but have no gravel to train on nearby, so will be doing 99% of rides on roads.

Just wondering how much of a difference/speed there would be on a proper road bike vs. getting a gravel bike with either road tires or even a full road wheelset to swap out.

I’m looking at the Tarmac SL6 Disc Sport for $2600 or the Diverge Comp E5 for $2100 (2021 model) or $1900 (2019 model). I could then get a wheelset like Hunt 34 mm rims for $600 and keep some GP5000’s on there.

I saw another thread where someone posted a picture of a Canyon Grail with some deep rims and that is what gave me this idea.

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It’ll be pretty negligible with road tires.

I’m definitely in favor of the dual wheelset, dual role gravel bike (and I just put my money where my mouth is - I have a set of LB AR56 / DT 240 wheels incoming for my Trek Checkpoint), but bear in mind that it’s the wheelset, plus $100 in tires, plus $100 cassette, plus $100 in rotors. I can’t imagine anyone switching all that just to go for a road ride or vice versa. Just be sure to account for those costs going in.

:+1:

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I’m thinking about putting a similar set of wheels on my Crux.

With gravel bikes, you just have to look at stack/reach dimensions and see if you can get your preferred postion for road riding. These days some gravel bikes are more mountain bikey and some are more road bike.

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Like everyone said -basically no difference.
Rolling-wise, you can put the same tire and wheel on them. Keep in mind that you probably want to get a cassette and discs too.

Aero-wise

  1. that SL6 is a pretty round tube bike. (220w in the Tour test?? The worst frame would be about 229w in that test and the best would be 203).
  2. The fork is the same width at the hub, but just a bit wider at the crown. (17mm ish). The tarmac has longer, thinner, aeroer fork legs. The Diverge has mounting points.
  3. Everything behind the downtube really doesn’t matter much because you’re on the bike pedaling. With water bottles /cages and a flat kit mounted (Diverage can hide that in the downtube - SPC says about 2sec / 40k https://www.youtube.com/watch?v=89KEevSRcGw), the Tarmac doesn’t all the advantage it did in the windtunnel.
  4. The Diverge has 20cm-ish longer wheelbase, making it a few watts less efficient when drafting a person.
  5. You can put aero bars and wheels/tires on the Diverge and get most of the aero benefit of the Tarmac. Aerobars are usually more comfy than round bars anyways.
  6. The tarmac has hidden cables - SPC says about 12seconds/40k https://www.youtube.com/watch?v=89KEevSRcGw

Other bits -

  1. The Tarmac can run a much bigger chainring up front. (Div 42t 1x ??; 46t 2x??), so you might be limited on top speed in group rides against a 50t road bike if you’re pedaling in the mid-30mph range.

I have a Trek Emonda road and Checkpoint gravel. I cant really tell the difference between them with the same tires on. I run 30c Vittoria Corsa Control on the gravel bike in road mode and 25c/28c GP5ks on the road bike, they seem to roll about the same in the real world. If I were to go back to a single bike, it’d be an easy decision aside from the paint job on the road bike being prettier.

If you’re doing longer rides in the country or traveling, I’d do the Diverge no question. If you want options, get the Diverge. If you’re doing 1-2 hour group rides and want something slick, get the Tarmac.

Similar topic in this thread

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I’m doing a similar thing. My next bike will be a Diverge with two wheelsets for road (700x32) and gravel (650x44). That bike will replace my current Synapse. I expect to lose very little speed, if any, and gain quite a lot in comfort.

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Why not 700x44 for gravel? The 2021 Diverge easily fits this size.

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I think this question can be broken down into two essential questions: frame weight and geometry. Features like 1x or 2x or the ability to carry stuff are all secondary or tertiary. I suspect the one-bike model here is better when you want or lean toward an “endurance” geometry for your road bike. In my case, my road bike is substantially lighter and with a more aggressive geometry than my gravel bike. Changing the wheel set on the gravel bike, or even changing the stem angle or length, won’t create parity.

In the end, it just depends on what you want in a road or gravel bike.

On @davewh question about 650 v 700, that’s a good question. Rolling over stuff with 700s is better, so I’m told by friends who I helped convert to gravel and went with 700s while I’m on 650s. I’m not changing the rims, but I’m unable to justify why I’m on 650 v 700. Is it a matter of acceleration and spinning up a 650 is easier than a 700?

I have a dedicated road bike but often use my CX for long distance stuff, road and gravel. if you set up the reach right it can be a comfortable ride, or surprising fast if you use, say a 17 deg flipped stem. You also often get wider gearing for relaxed climbing.

Below is my Marin cortina set up for a 400km audax, average speed for that was 29kmh.

And below doing the fun stuff!

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If I had to pick between my road bike and my gravel bike, i would choose my gravel bike. I can do more with it. I have one set of wheels with fast road tires and one set of wheels with fast gravel tires. If i only had a road bike, i couldnt do gravel, or CX if you really wanted to.

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I did this. Cervélo Aspero GRX 2x11 with 3 wheelsets. First is the stock alloy 700c wheelset that hardly gets used. I might sell them. Then I bought some 650b alloy wheels to maximize my tire width (48 mm) for more volume and comfort vs maxed out 700x42. Then I bought Light Bicycle WR50 (Carbon, 700x25i) as my road wheels, running GP5000 28c (measures 30 mm on these rims) with latex tubes.

I threw on a comfortable carbon seatpost as well. The bike is very comfortable and very fast. My complaint with this bike is the Easton crank doesn’t have the right chainline for GRX, so I have a GRX crank on the way.

I recently took a vacation to an area with great road, gravel and XC MTB trails. I brought the Aspero with my road and gravel wheels and road all three surfaces (sometimes in the same ride). It was nice to not have to bring two bikes.

I also like that I only have to maintain one bike and feel more justified spending money on upgrades to it, since it gets more use.

Go for it

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Yup, been running a stock Allez on road and maintained gravel. Works great! I prefer the road though, which is why I chose the Allez.

Have you tried adding spacers on your crankset spindle? I also have the Easton/GRX combo with 2x 46/30 and with a few spacers on the drive side, shifting has been spot on.

My preference is 650 for gravel so I can have more air/tire on a smaller rim. I can ride lower pressures, be more comfortable, and worry less about the tire when off-road (which is new to me).

Have to ask - how are the LB wheels holding up? I’ve been hovering over those for a while and wondering if they’re good. I’m a bit heavier at 95kgs than most so wondering what the buying experience was like, if you had any issues and what they feel like to ride. I’d be upgrading a set of DT Swiss Spline 1850s set up tubeless with them. :grin:

OP here, thank you everyone for the great advice.

If I am planning on being 90-95% road, is there maybe a better option than the Diverge? I assume some of the gravel bikes have a more race like geometry.

i’ve been racing crits and cross on my cross bike (with two wheelsets) and it’s been more than fine for the past few years. It won’t even really hold you back if you’re racing (probably forever, but at least for the first few years)

Makes sense - but to get the benefit of 650 over 700c, you should put a 2”+ tire on the 650s.

On the new Diverge, you can easily fit 45 tires on 700s, and could probably push that to 50mm.

On 650s, the recommended max is 2.1”, but I bet you could push that a little more to 2.2” or 2.3“.

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