Sorg67

mstateglfr made and interesting comment in another thread that the only benefit of a carbon frame with 40mm tires is weight and the weight advantage is not that significant for recreational riders.

This comment is interesting to me. I was advised to get a carbon frame by a road rider. It makes sense to me that on tiny road tires, vibration dampening of a carbon frame might make a difference. But with bigger tires on a gravel bike, the vibration dampening might not be significant and the carbon frame might not be worth the money.

OTOH, I am considering a second set of tires to have more road orient tires if I am going to start riding with the roadies. And perhaps if I do that, the carbon frame will be a significant benefit.

Do I understand the considerations correctly?

Koyote

Hell, I'm not even convinced that cf makes for a smoother-riding road bike. Maybe my sample size is too small, but my steel-framed road bikes (1x Cro-Moly, 1x Reynolds 853) ride just as smoothly as my one cf bike. And as mstateglfr pointed out, the high-volume tires on a gravel bike will further mute any differences.

A cf frame will result in a somewhat lighter bike, but that benefit is vastly overestimated by many cyclists.

shoota 

I've ridden both heavy steel gravel bikes and now a somewhat light (19lbs) carbon gravel bike. I'd take the light bike all day long and twice on Sundays.

chas58

IMHO -
I've periodically ridden aluminum and carbon versions of the same bike, and there is no comparison. Carbon was tons nicer. Maybe its just the resonance frequency. Shoot, one of the reasons I like steel is that the vibration is just so, so well damped. Aluminum is the opposite.

There are crappy carbon bikes out there, but a well made one can be nice and cush, while at the same time offering explosive acceleration (mine does, and weighs 16-17lbs). I was shocked the first time I went down a heavily washboarded road on 32mm tires and felt very comfortable. I tried doing that 15 years ago, and it really turned me off on gravel (with what was available in those days - washboard was my nightmare).

That said, I have put a lot of happy miles on an aluminum bike with good tires (at correct psi) and a good seat post (thudbuster ST). That is a very comfortable and responsive ride. That resonance frequency gets dampened a lot with the rubber above and below the frame.

Yeay, I love Aluminum. It is very responsive, priced right, and can be tuned for comfort. With something like the Canyon Grail, I'd be tempted to go for the Aluminum model. But if you have the $$$, put a priority on both comfort and out of the seat responsive acceleration - well nothing beats a great frame.

mstateglfr 

For sure there is a ton of difference in feel between a heavy and light bike.
A true 19# gravel bike in medium/large sizing is pretty darn good for weight.

The difference between a true 21# bike and 19# bike just isn't much. That's the difference I was mentioning in the other thread as it's a realistic average difference in frame weight(1000g) since all other components would be the same.

I was saying that tire width is going to affect specifically the road feel more than frame material.

Blindfolded, i certainly wouldn't known what frame material im riding based on road vibration if I have 50mm tires at 30psi.

Koyote

I would, too, all other things equal. But all other things are never equal, in this case. And when you look at the actual physics of it (and play around at a website like this one), it's apparent that a lighter bike is usually not much faster.

'Course, it partly depends on how much lighter...But if we're only talking about a couple pounds, it's not a big deal.

shoota 

Agreed and agreed.

I'm at the point in my life where I'm never gonna be the fastest, but I'm also not the slowest. What it comes down to is how the bike feels, even if it doesn't technically add speed. I want a bike that is fun to ride. What that is for each person varies. And there ain't nuthin' wrong with that.

Toadmeister

As a 6’4” 270# Clydesdale, I hesitate to invest $ in a carbon frame when my body's mass is literally the Elephant in the room saving 2-15 lbs on a frame is insignificant for me.

As such I’ve found my sweet spot with steel on my Jamis Renegade. Have had 3 different Aluminum bikes in the last 8 years or so and the Steel wins hands down! My current aluminum fat bikes frame is far too stiff, the fat tires on low pressure still don’t compensate for that dog of a frame.

I have ridden carbon frames and they do feel pretty sweet, I can notice the difference. They almost feel unnaturally light and fragile to me (that’s perception, not a fact). If I were a skinny road racer I could see the attractiveness. Otherwise, I love steel.

Sorg67

This has been a very useful discussion. I think I am going to get the carbon frame, but I understand it will not do much for comfort or speed. I will just like it and that is the only thing that really matters.

Koyote

As long as you like the frame and it fits well, you'll be happy with it. And if it is a bit lighter, as shoota suggested, it might feel a bit more lively - especially when you are up out of the saddle, attacking a climb.

mstateglfr 

Yeah, go for whatever material gets you all giggly to ride. My comments earlier weren't to bash one material, they were to really compliment all 4 main frame materials as they are all quite capable of being built into great bikes.

dwmckee

I have taken several courses in the dynamics of vibration. Certain things are better as dampening high frequency vibrations but do little for low frwequency and visa versa. One type of dampening (rubber tires for example) only work on vibrations in certain frequencies while other materials or systams are better at other frequencies. The more sophisticated dampening systems normally rely on a combination of things, not just one for dampening a broad range of frequencies. Rubber tires are only good at handling part of the problem, but when combined with a properly made carbon frame together they can be very good at dampening a broad range of low and high frequency vibrations (washboard is low frequency and gravel texture is high frequency). Rubber tires or a CF frame alone really only handle one half or the issue or the other. A car is a great example, The coil springs handle just part of the problem, the tires help and the shock absorbers and frame flexibility of the car together handle the rest for a nicely refined ride. Drive a care wih the tires inflated to 60 PSI or with bad coil springs or bad shocks and see what it feels like with just part of the vibration control system working.

CF frames also have an advantage beyond weight savings or dampening. The frames can be built with different carbon layups all throughout each member to finely tune stiffness in different directions where symmetric steel, aluminum or titanium tubing do not have this flexibility (though hydroforming or butting has some limited benefits here). This is where a well made carbon frame can win out in creating the holy grail of laterally stiff but vertically compliant characteristics sought in a good gravel bike.

mstateglfr 

Money well spent. /snark

Toadmeister

Well described. My bachelor's degree is in composites with an emphasis on laminate analysis. My background in vibration is less educational and more industrial but from personal experience I concur with your words.

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dwmckee

Thanks. Your steel Renegade is a good example of a well designed system of a steel frame in combination with the right tires can be a great gravel bike. Aluminum can be a good material too, but it seems that making a GOOD aluminum frame can push the price up to where carbon or steel start to make more sense.

Sorg67

My current feeling is that the performance elements of Carbon are not going to materially change my performance. But I think it is going to feel better and I will like it.

Who knows, maybe I will even giggle a bit.

Chi_Z

the problem is every hipster wants an alloy bike, so a decent steel or titanium frame is more expansive than carbon

rosefarts

I completely agree with you about weight but you are making the wrong conclusion about carbon and other materials. It's the setup, not the frame material.

A carbon frame should be 950-1200g where an aluminum should be 1400g and steel is going to be 1800-2200.


So we're realistically talking 2.5 lbs difference from the pure racing rocketship to the friggin cast iron Surly. 19 vs 21.5 lbs for the same build. Can't exactly call either heavy.

Sure we'd all love to ride 2.5 lbs lighter but neither are a tank. Lower end metal bikes, old bikes converted, and vintage bikes with wide tires are heavy, almost entirely because of the setup, not frame.

Compare a Ritte Satyr or even a Motobecane 853 gravel to something carbon and comparable, and you're not going to see a huge difference.

shoota 

That's totally fair. At one point I went full WW on my Raleigh Tamland and had it down to 21lbs. It felt light enough for sure.

Elvo

I only had about $1200 total to spend on a bike so a carbon frameset was all I could afford

paloaltan

LOL

I can't say much for feeling a difference in dampening, but I sure do appreciate the lightness. Coming from an aluminum mountain bike, the weight difference really gives me a different riding experience where I feel like went from driving an SUV down to a Miata or S2000.

tFUnK

The difference isn't big in terms of holding a constant speed, but a lighter bike just feels more responsive when you put down a sudden acceleration out of turns, over technical sections, etc. If you do a lot of sudden stops and accelerations you will appreciate the weight savings. But sometimes on dodgy, rough terrain a heavier bike actually feels more grounded. And I'm less worried when I tumble on a metal frame than on a carbon frame.

Sorg67

Each one of these comments gives me a different perspective. I like the idea of responsive acceleration. Won’t make much difference in average speed, but will be fun.

I like hills. We do not have much hilly terrain, but I often do a few hill repeats on the few hills we have.

I like the feeling is sitting in my seat and cranking by some guy who is standing up and huffing and puffing up the hill. Of course, it won’t be quite as satisfying when I am on a bike that weighs 10 lbs less.

Any decent bike is going to weigh a lot less than my 30 lbs hybrid. Not sure what my cromolly fram MTB Bike weighs. I want so say 28 lbs or so.

Whether a new bike is 18, 20 or 22 lbs will still feel light compared to what I am on.

msu2001la

My new carbon fiber bike actually a little bit heavier than my older aluminum bike.
It has discs, vs rim brakes, and the stock wheelset is pretty heavy. I notice the added weight when climbing or picking the bike up, but I don't really notice it when riding on flat roads.

The ride quality on the carbon bike is way better. My aluminum bike feels really stiff and harsh in comparison. The carbon bike feels like it floats over rough washboard and gravel.

nicovlogg

I'll be the dissenting anti-science voice here. I've ridden a couple of nice carbon bikes, including one very nice Cannondale gravel model, and lots of aluminium bikes, and on the gravel we have round here, nothing comes even nearly close to my 'heavy' 23lbs Cotic Escapade with a steel fork. It feels plush and comfortable in a way that goes way beyond tyre pressures.