You think it’s accurate that a gravel bike is potentially 20% slower than a road bike
 

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Is this a trick question?

haha. no. genuine question. i own a gravel bike. just curious

Only when I am on it. But (a) I am also 20% slower than most people on my road bike, and (b) my gravel bike is my road bike.

Often it is slower to ride on loose gravel and steep, rutted inclines than it is to ride on smooth, well-maintained roads with more moderate grading.

If your gravel bike slows you down on the road, you probably just need more supple tires.

For ex. today I did an exhausting 80km ride on my gravel bike, 1100meters (85% of this trip was on national park paved roads). I feel I'm in pretty damn good shape but one of the last climbs (very demanding), a group of road bike guys passed me, and quite fast it seemed. Although, at the top of the climb they were all stopped taking a break which I didnt :)

I’ve been riding CX and now a gravel bikes since about 2014 after riding a Madone for a bit. I’ve kept up with roadies fine, and did so, day of after making the switch. My first long fast ride (20mph is fast for me for 40-50 miles ) wore me out pretty good on my first ride with the CX bike but that’s because I was in the front 3/4 of the time on the knobbies. I’ve never had my legs die out like that. My point is that your engine is going to limit you more than anything else. I pushed the engine and tried to be the hero our front all day. It wasn’t my bike.

I will say big knobby dirt tires are a little slower if you’re going a long way on really smooth pavement but for most typical trials and general riding they really aren’t. I am on 700x38 grevelking now and I don’t think they are slower at all. They are a good all around tires that rolls well The CX and gravel bikes are a little heavier so there is that.

A more premium light CX bike with more aggressive geometry, full road gearing, and road slicks is going to lose nothing perceivable unless your elite level - that’s my opinion.



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If there is a difference (which from your example isn't necessarily the case -- they may have been at the beginning of their ride), it would most likely be the tires.

I ride a 650B gravel bike with somewhat knobby tires everywhere, and I'm definitely slower than the serious roadies(at least they LOOK serious considering their kit). Where I live it's all incessant climbing, whether on the road or the dirt. I'm strong and can ride forever, but I get passed all the time. I think it's a combination of my engine, my bike, but also just the way I like to ride - I'm not in a hurry.

This is a great example as to why advice here should be weighed.

Road bikes are typically lighter, usually more aero, handle better on pavement, and are generally geared for (wait for it) riding on the road.

You'll never bridge that gap, no matter how supple your tires.

Lower end road and lower end gravel there is probably not much difference. For nicer stuff though, it's pretty huge.

I just don’t care. I ride solo in the boonies going on adventures. I guess if you are competing a dedicated road bike will be faster.

I own many bikes, and yes, the gravel bikes are slower. They are heavier, and less aero, mainly due to a higher riding position. The fat 28mm tires are slow pigs due to their weight and high rolling resistance. Despite all the nonsense propagated by the bike industry these days, 23mm tires pumped up to 110+ psi are unquestionably faster on pavement.

Depends on how heavy you are and where you want to ride. On gravel, I can get away with relatively narrow tires and lightweight wheels because I am light and careful.

Small differences in weight, especially wheel weight can become a major performance issue if you are riding with the 'fast crowd' on the road. Getting dropped on accelerations out of corners or on climbs can cause you to spend too much time riding solo into the wind. So when you are pushing it close to the limit already, a 5% performance disadvantage due to a heavy set of wheels can manifest itself as 50% extra suffering when you get dropped from the pack.

A gravel bike is only 17% slower than a road bike.

Not slower on intended surface!
If paris roubaix was all cobbles then you would see gravel bikes being used.

I don't think "are gravel bikes slower on gravel" is the question.

I think we've all put up with a 40mm or more tire on pavement to get to the fun stuff. Sometimes it feels like a tractor. Other times I think, wow, this isn't terrible. I never think, while riding a gravel bike on the road, that I'm faster than if I was on the road bike.

I don't get my wife to follow me and switch bikes. I don't think she would if I asked. Too bad, I've got one I'll do soon that would be great for gravel, road, mountain, then road bike. In that order.

If you replace an Ultegra 50/34T crank with a GRX 48/31T or 46/30T crank, with an 11-speed 11-X cassette, at most you have lost only the topmost gear. So if your speed is dependent upon spending most of your time in the 50T/11T gear, then gearing will make a small difference to speed. Otherwise the gearing makes no difference. There is at least as much variation in geometry within pure road bikes as there is between the average road and average gravel frame. (Mine, for example, is almost identical to that of a Trek Domane.) If you compare a time-trial frame to a gravel frame, there will likely be a significant difference. If you compare a Domane to my bike, there will be none.

So it looks like it comes down to the tires and the surfaces you ride on as being the primary differences. (One might also choose heavier, more robust wheels, but people like me do that on-road, too.)

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On the left, 1X Ritchey Swiss Cross on tubeless 700x35s, ~25lbs. On the right, Cervelo R3 on tubeless 700x25s, about 18lbs. Identical route. The difference in speed is about 8%-- brought about mostly by the lighter bike being slightly quicker uphill (lighter?) and slightly quicker on the descent (more gears.)

Gravel bike could be slower, sure. Could be faster though.

If you ride a flat 20mi course on pavement with a road bike and compare it to a hilly 20mi 2000' climb gravel ride with a gravel bike, then sure your time will be slower on the gravel bike and maybe that's 20%.

If you ride a 20mi flat course with a road bike and gravel bike, I doubt the time difference will be 20%.

If you ride that same flat 20mi course with both and slap road tires and gearing on the gravel bike the time difference should be even smaller.

If you ride that 20mi hilly gravel route with both bikes, perhaps the gravel bike is faster.



As for your experience with roadies passing you...i wouldn't give any thought to that.
maybe they were early int year ride and you were late in yours...fatigue difference.
Maybe they just put out more watts/lb or kg than you so they are then faster.

I don't know about the percentage, but gravel tires are heavier and have more rolling resistance than road tires. Yeah , the gravel bike with gravel tires is slower than a road bike, given the same power output.

Guess a fair apple to apple comparison is my 17.6 lbs carbon road bike vs. my aluminum gravel at 22.6 lbs. Carbon has 25mm tires at 100-110 psi, the gravel with the road wheels and tires are 31mm at 70-80 psi. Carbon feels faster, my avg. for similar courses at about same effort is the carbon is about 1/2 to 1 mph faster on avg. The carbon certainly feels lighter and quicker. Totally non-scientific analysis.

My '76 Raleigh Competition, with 32mm Panaracer Gravelkings, comes about as close to road bike performance as I dare. This thing flies with 23's and light wheels. Very versatile, but some would say not a true gravel bike because it maxes out at 35 mm tires.


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The exact number is 28.99.

I totally agree. My "gravel only" bike is a 29plus, 29x3. I love it on gravel but it is not suitable for much pavement, although different tires could make a difference. Then I also have my "mostly pavement" gravel bike, 700x40c which can handle both pavement and gravel (but excels at neither, at least with the tires I've been running). When you're riding to escape civilization, your speed isn't that important.

But wait, my bike has "Road Plus" tires--shouldn't that make me faster?;)

Show your math please!

Dr Iso showed the math, 8% it is:thumb: