Having never owned a carbon bike (currently own steel road and aluminum cx), I'm wondering what material provides a more comfy ride over gravel. I realize the type of steel, type of carbon, the builds/welds/layups, etc., make a difference, but this is more 'generally speaking'.
As a point of reference, the following two bikes from Jamis have a similar geometry (chainstay length, BB drop, etc.). I'm 150 lbs, and the gravel I ride is relatively smooth in most sections, but the roads underneath the gravel are often pot-holed or have ruts.
I don't have much experience with different materials on gravel, but do have such experience with road bikes...And I suspect the answer you'll get around here is that tires (volume, inflation, type), saddles, frame geometry, etc, will all trump frame material.
Some observations from ownership and recent testing.
It's MTB and fattie, but my wife and I have almost identical Trek models with each having one made of the plastic or recycle beer cans. There your bike engine makes far more difference than frame material.
Testing a bunch of gravel or CX or tourers with my son recently got him liking steel like me. He observed the AL bikes felt stiff an responsive if you stand on it but liked the steel sound and feel or flex.
Some associates who've spent time with the Trek Checkpoint that has the soft material around seat post say it is very comfy and also stiff or responsive when you're out of the seat.
All this testing stuff and some family bike rides made the tires stand out as really influencing the ride. That comes to mind when I think of our Farley fat bikes. You can't really feel which is plastic unless you're pecking it them with your fingernails.
Really, some bikes just kind of grab me the way some guitars do. It's not always rational. Still, I often like steel and plastic bikes in same way I like Telecasters and 000 but know many others choose differently.
I think the OP better go try that Checkpoint SL and a top steel and maybe a ti bike too be really sure. Better yet, buy them all so you really know.
Everything I am about to write is a generalization, because engineering can effect a lot of things. Almost every steel frame is going to be comfortable. The real trick with steel is making it stiff enough without making it a tank. A cheap steel frame will be comfortable (it may even be light) but flex like crazy. Carbon is a much different material than any other frame material. All other materials have certain properties that cannot be completely changed. Carbon can be engineered in many different ways to tune a bike for whatever you are looking for. Carbon can be tuned to give just as comfortable a ride as steel, while being much stiffer and lighter. However, it has been my experience that most carbon frames are built overly stiff and are uncomfortable for long distance riding. So while carbon has the potential to make the best gravel frame, in my experience very few manufacturers are using it properly, they try to make everything stiff like a road bike for the Racer/Strava crowd. I have not tried the Salsa Warbird, but it does look pretty promising. Personally I went with Titanium because it rides awesome, is stiff enough, lighter than steel and won't rust. My bike would probably be a couple pounds lighter with a carbon frame, but I'll take the guaranteed ride quality of titanium in exchange for a couple extra pounds.
It comes down to engineering. I've been of carbon bikes that are so stiff they feel like you are riding a brick. On the other hand every BMC bike I've ever ridden be it carbon or aluminum have been stiff enough while being extrodinarily comfortable. Those guys understand engineering perfectly. It's too bad they don't make a true gravel bike and instead retrofit their endurance model.
There are so many other factors from road+ tubeless tires to iso-speed decouplers and futureshocks that I wouldn't discount any material. My current gravel rig is a Kona Rove NRB which is an alloy framed bike with road+ wheels. It's been great on gravel. I have an old Jamis Dragon steel 29er hardtail and I can honestly say that that the Kona with it's alloy frame is just as comfortable. The steel Jamis Dragon feels springier and is very smooth but I don't think of it as being more comfortable than the alloy Kona Rove NRB.
These days the material itself is not critical to comfort. They've come a very long way with both carbon and aluminum. You still have to try everything. As Guitar Ted is always writing too many bike companies throw on these still carbon cyclocross forks. They want to save weight but don't want to invest in a supple carbon fork since they already have the cross ones available. That will ruin any frame. You just can't look at a bike on website and know how it rides from build kit and geometry chart.
I ride a 2017 Jamis Renegade Elite carbon bike that replaced a Salsa Vaya steel bike as my primary gravel bike. The Jamis frame is very well engineered to be stiff where you want it (e.g. BB, lateral movement on the fork), but exceptionally smooth at the saddle with enough flex to noticeably dampen vibration. It is a much more comfortable bike overall than the steel Vaya; even running with the Vaya running slightly wider tires. The Vaya's steel fork definitely had a bit more flex, but that was noticeable laterally as well and steering was nowhere near as precise.
Overall, I agree with others that are many factors and components that come into play that effect overall comfort; not to mention individual preferences. However, I'm really impressed with the carbon frame on my Renegade.
Just my 2 cents worth. Have owned aluminum, steel, carbon and titanium bikes and as previously said have found it all comes down to engineering. My aluminum and ti bikes were cyclocross bikes that were built quite stiff for racing, although the ti bike was much more comfortable, I would start to feel pretty beat up after 45 miles. The carbon is a road endurance bike which I love even more after putting 28 mm tires on it. Only ride it pavement and easy gravel and boy is it fast on really smooth trails. My very favorite is my Niner RLT9 steel which is built for gravel, is not as fast on the road as a road bike, but can handle pretty long gravel rides really comfortably, and will do single track if you want to crack your stock rims .
I love my steel gravel bike, and don't plan on changing any time soon, but if companies will use the amazing advances in carbon engineering for gravel specific bikes, I'm sure that carbon would be pretty well unbeatable.
I’m the last couple days I’ve been trying out different gravel bikes. I tried steel and carbon, including very similar geometry/spec bikes from Jamis. I’m selling an aluminum cx bike. The first four rides, I didn’t feel what I was looking for, regardless of material, which means the engineering and bike spec (tires especially) make a huger difference. As would fit, of course.
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