Mountain Mitch

Can somebody please explain the reasons to buy a carbon MTB?

I am looking at two identical bikes: one carbon and the other ALU. They each weigh within a few oz. of 30 lbs.; the Carbon bike is about one pound lighter overall (3.5%). The carbon bike is $2000 more than the ALU.

Aside from trendiness is this weight difference really worth that kind of money? Plus I know aluminum is strong and durable. While carbon is pretty good it is still a more fragile substance.

prj71

With the a $2000 difference in price tag, I would bet the carbon also has better components.

Which bike you looking at?

justin70

No way carbon is the only difference if it costs $2000 more.

FrozenK

What bikes are you looking at? Not that many with identical spec and frames offered in carbon and aluminum.

And carbon isn't fragile. That's a meme that needs to go away. But if what you are looking for is people telling you that you should buy the aluminum one: you should get the aluminum one.

gsa103

Most manufacturers say that the carbon versions of their frames are more durable than the Al version.
Al frames can fatigue at the weld points when really abused.

I wouldn't hesitate to buy an Al frame bike, but a modern carbon frame will be lighter and at least as durable. For example, a Santa Cruz Bronson Al is $1899, the carbon with better shock is $2999, so ~$1000 difference, which is typical. For $2000, I would expected better components also.

Mountain Mitch

Heh-heh! I ended up going for a different carbon bike. Intense Tracer T275c. First ride this morning. Very pleased with the bike.

Now about running tubeless.....

prj71

Do it.

MarioT

You'll really like it an never go back. The lower tire pressure is great for climbs with roots and such, as well as berms.

Mountain Mitch

I've taken the tubes out. Now if we can get a break in this shocking weather I'll go out for a ride and figure out what all the excitement is about!

justin70

Don't run the pressure too low

ussprinceton

I have aluminum road bikes, but carbon mountain

Mountain Mitch

Love my new bike. Don't think the tubeless thing is real. Carbon is also more or less a marketing gimmick. Saves very little weight - but does make you feel cool and in with the in crowd!

Cyclist0108

OK, now try it with valves and sealant.

prj71

It's real.

1.) You don't have the tube working against the tire (friction) when it is rolling over uneven surfaces. Which makes it harder to pedal.

2.) If you puncture the tire, the sealant seals the hole up within seconds. If you had a tube, you would be stopping on the trail, possibly getting eat up by mosquitoes, and spending 15-20 minutes of your time removing old tube, installing new tube and pumping it up with a hand pump.


Ummm...no.

1.) Saves weight...Less gravitational force to overcome when climbing.
2.) Dampens vibrations
3.) Longer fatigue life than aluminum.

Mountain Mitch

Well, those are the theories. I'm talking about real life.
-The weight saving of carbon is minimal and could probably be achieved through careful component selection (or laying off that breakfast bagel). I'll try and convince myself I was smart to pay double for a carbon bike that shaves a few grams next time I'm riding up a steep hill
-I cannot feel the 'friction difference' you are talking about; so why should I care? I doubt it is real. Just more marketing jumbo jumbo. Show me the actual science with proof it is a factor for a recreational rider.
-A minor puncture may seal itself (if your sealant is less than a few months old) but a major one is much more of a catastrophe than with a tube. Plus, I normally get maybe one puncture a year so it is no big deal compared with the fuss of 'tubeless' (does anybody really replace the sealant according to the manufacturer's recommendations? )

gsa103

Everyone that has measured rolling resistance has shown that tubeless is faster than a butyl tube.
TESTED: Rolling Resistance of Tubeless Mountain Bike Tires
There's the data. The difference is about 5W per wheel, or 10W total. That will make the average recreational rider 5% on any given climb.
I switched to tubeless after getting 4 flats in 4 rides (goat-heads). Haven't looked back.
If you don't get flats then it's doesn't really matter.
As for sealant replacement, there are a couple of scenarios:
1) Sealant seals the hole. No further action needed.
2) Sealant dried out. Install a tube, no mess because the sealant is dried out.
3) Giant gash. Boot required, this can get messy but it's the least common. And once you pour the sealant out it's not that bad.

Mountain Mitch

I gotta hand it to you. I asked for studies and you came up with one. I have some disagreement with some of the data (eg. Running with sub operating amounts of sealant) but overall it seems to make the point. I guess my bike is doing its best - but I still don't feel any difference.

I agree that if you ride where there are lots of goatheads or cactus spines, anything that makes flats less of a bother is worth it.

However, I still think this is primarily about marketing. Buy the new wheels, the new tires,the tape, the sealant; remember to replace the sealant every three months; you'll tear the tape occasionally while replacing sealant. Fuss and spend for an item that was largely ignored or inexpensively repaired if it was punctured. But I admit I went for it. Just wish I feel I'd got more for my time and money.

bikingtotown

I've had two cracked aluminum frames. So I was ready to try something new. I like the ride quality of carbon better seems much less clunky. Can't say anything about durability yet.

prj71

None of what I posted is theory. It's actual facts.

Now imagine the careful component selection coupled with a carbon frame. Your legs will thank you for a lighter bike at the end of a long day in the saddle.

Why should you care?

https://www.thoughtco.com/standard-v...-tires-2403286

Mountain Mitch

Well, keeps the bike shops in business I suppose.....

fietsbob

not me, but we have a few Mountain bike trails here , most of the bikes at prices people are willing to pay are aluminum.

Not a lot of them have the money to get a Carbon MTB...



...

ebow3d

If you watch this video, then carbon is clearly the stronger option:

stockae92

If everything is the same except for the frame material and $2000, and if you don't race, I will go for the AL bike, spend $1k wheel upgrade (sell the old wheel to get some money back), another $500 for other bikes and accessories upgrades. And you still have $500 (plus tax saving) left to buy some Apple stock and watch it grow.

If its my money, get the AL bike, ride it (a lot), replace stuff when it breaks.

Light weight is good, 1 lb won't stop you from making it to the top of mountain. Lighter will only get you there faster.

PaulRivers

Lol, yeah, I got the whole "new flats with tubeless and sealant" speech. Rented the bike for a week, got a flat halfway through. The green sealant clearly marked the spot where the flat was without sealing it...

If I spun the tire around and let it sit a minute it "closed" the leak, but as soon as I tried to ride it again it burst open.


It wasn't as hard to fix as I had expected - the fix involves putting a fresh tube into the "tubeless" tire for the ride home. It was a bit messier though getting green goop onto my hands.

prj71

Just rode 55 miles of trails this past weekend. Was riding along and all of sudden my back leg was getting wet. Turned out I punctured the tire and it was squirting out at my back leg, but the sealant took care of it and I didn't flat.