Carbon Rims

paul.skibum

Nice little video and interesting info:

http://dirtmountainbike.com/features/carbon-mtb-wheels-do-you-need-them.html

Ferrals

Yeah that is interesting. I have to say I am dubious about buying rims direct from china, if I won the lottery I'd get a pair of ENVE's but I wonder how many people who arent semi-pro can justify them? I know exactly what my mrs would say if i explained i was about to spend 2.5k on a pair of bicycle wheels!!

BloggingFit

Not sure on the aluminium rim creating more of a footprint due to flex idea. I can't see it being by a noticeable margin. You would gain more using a wider Carbon rim and matching in the tyre width to put down more footprint that way which you couldn't achieve with aluminium without a big weight penalty.

Clearly has his ENVE PR head on talking Chinese rims and they have had their issues with failures.

All very interesting though and I like what he says overall.

paul.skibum

Made me think I wouldn't get a whole lot of benefit from Enve's - I definitely dont ride hard enough but might enjoy the extra snap. Interesting his view on the plusher feel of alloy rims though.

BloggingFit

I noticed the harsher ride when I first put them on my Remedy but then I also paired up with a narrower section tyre to get more footprint on the wider rim which would have contributed a little. They also showed up the short comings of my Fox 34s so I doubt anyone running newer Fox forks would enjoy them!

To be honest going back onto my aluminium wheels didn't really show up much in the way of comfort, just more flex, less direct, a little less zip when accelerating. I think the harshness would be far more noticeable on a hardtail which I have found on the Bird but again you soon forget about it through the ride.

Perhaps an experiment of Carbon front and aluminium rear for hardtails is in order. Lose acceleration, gain comfort, keep directness of the front.

poah

other than enve being really expensive, what makes them the "best". as far as I can see they still get trashed

BloggingFit

POAH wrote:

other than enve being really expensive, what makes them the "best". as far as I can see they still get trashed

I guess you pay for the name, warranty and higher fabrication costs of being made in the US.

njee20

Nothing particularly special about Enve's warranty.

Name and the 'US built' tag.

I'd not buy their MTB rims, just don't see the point in paying that much when they really don't seem to offer any advantage whatsoever over Light Bicycle et al.

Their road ones are a bit different, given unlimited funds I'd have some of those!

That article is so full of bollocks though:

Acceleration is one thing that is evident on carbon wheels, the lack of flex translates into a fast pick up of speed

you might even want to set the compression on your shock a bit lighter with carbon as an aluminium rim will ply with the shape of the ground more than a carbon rim

The inherent stiffness of a carbon rim means that you can build it a bit softer but you can’t make that much of a difference, you can however build an aluminium wheelset stiff and gain some of the compliance and grip but you won’t get the pick up and zip of a carbon rim.

How can you build an aluminium wheelset stiff (short of using thicker spokes) and how does that improve grip and compliance!?

I've read a far better article talking about the difference in stiffness and what not, which actually quantified it, and it was absolutely minute. That, like most things on Dirt, is just complete rubbish.

Angus Young

njee20 wrote:

That article is so full of **** though:

Acceleration is one thing that is evident on carbon wheels, the lack of flex translates into a fast pick up of speed

Without a doubt my Kona is more accelerative with the Superstar carbons I put on it. So much so that on first pedalling the bike across my drive I involuntarily said "WOW!" out loud. It wasn't a subtle improvement. I still notice it every time I set off. No doubt some of that is due to the new hubs/tyres/better spokes etc. but I'd guess some of it must be down to the carbon rims.

njee20

In that context though, how is rim flex making any difference? As you accelerate you twist the hub forward, and it takes a minute amount of time for the rims to 'catch up'. So building with really fat gauge spokes and using proper lacing pattern, and even hubs with a better bracing angle may well help here. Rim stiffness won't.

Your wheels felt better because they weighed less. That they're carbon isn't specifically relevant to this. In fact most of the lightest rims out there are aluminium.

benpinnick

Its a trade off on weight though - I like carbon because I can get a 30mm inner width to give a nice tyre shape, while weighing less than most alu rims. And in terms of strength the carbon 35mm option will in my experience outlive 400-ish g alu rims easily.

I don't much buy into the stiffness/feel thing though - tyres make a way bigger difference than rims. If there is a difference its hard to spot, other than g for g stiffness of carbon is higher, but then you'd just be running a bigger stiffer, heavier alu rim anyway, so that is negated.

Angus Young

njee20 wrote:

In that context though, how is rim flex making any difference? As you accelerate you twist the hub forward, and it takes a minute amount of time for the rims to 'catch up'. So building with really fat gauge spokes and using proper lacing pattern, and even hubs with a better bracing angle may well help here. Rim stiffness won't.

Not sure I'd go so far as to categorically state that "Rim stiffness won't." But yes, as I say, many other factors will be coming into play.

Likewise, the bike is definitely more accurate and confident at the front. The wheels were fitted at the same time as a Pike, carbon bars and a High Roller II (tubeless) up front (Ardent Race at the back) so, again, it's very hard to tell how much of the improvement is down to the wheels.

njee20

Angus Young wrote:

njee20 wrote:

In that context though, how is rim flex making any difference? As you accelerate you twist the hub forward, and it takes a minute amount of time for the rims to 'catch up'. So building with really fat gauge spokes and using proper lacing pattern, and even hubs with a better bracing angle may well help here. Rim stiffness won't.

Not sure I'd go so far as to categorically state that "Rim stiffness won't." But yes, as I say, many other factors will be coming into play.

Likewise, the bike is definitely more accurate and confident at the front. Again, the wheels were fitted at the same time as a Pike, carbon bars and a High Roller II (tubeless) up front (Ardent Race at the back) so it's very hard to tell how much of the improvement is down to the wheels.

Well yes, a carbon rim is far stiffer, but that's about lateral loads and handling, not acceleration over an identical aluminium rim. Much of it is how it feels anyway, more than an actual empirical difference.

Ben - wholly agree (and that's why I went carbon, rather than a lighter Stan's Race Gold or similar), was just observing that it's a common misconception that carbon rims are inherently lighter. They're not - most carbon XC rims are on par with a Crest, and heavier than the aforementioned Race Gold. That they're wider/stiffer/stronger for that comparable weight is the advantage.

rockmonkeysc

Good video. Bad Ass Bikes is my local shop, Box builds a very good wheel, he knows his onions. Rediculously fast enduro racer and still on the same set of 29er Enve rims he built three years ago, they look well used but still in one piece. I'm not convinced by the Chris King hope hubs though.