The Elusive Promise Of Carbon Fiber: Wheels

Last week I wrote about this subject in relation to bicycle frames for 29"ers. Today I want to talk about another major component that carbon fiber is used for: wheels.

Does carbon make wheels "better"?

Several years ago, 29"ers were not getting the "best" engineering, tech, or features like the smaller 26"ers were. Back then, (I am talking like '07-'08), you could get on a 29"er, slam it into a corner, and most likely you would feel a lot of wheel flex. Aluminum extrusions for 29"ers were mostly scaled up 26 extrusions and not specifically designed for the stresses that bigger wheels cause when riders do that mountain biking thing. The answer back then was carbon.

At that time, a Utah based company named "Edge Composites", (Now Enve), rolled out a couple carbon 29"er hoops that radically changed how riders would perceive the 29"er handling traits. The Edge wheels were stiffer. Way stiffer than anything else out there at the time. Yes- they were, ( and still are), super expensive. But if you could afford them, they would radicalize your 29"er experience. In fact, it took frames a while to catch up to how far Edge had taken the possibilities for frame stiffness and wheel rigidity in concert with each other.

But since then, aluminum designs for wheels in the plus size have come a long way. The gulf between aluminum and carbon in terms of ride performance has narrowed dramatically. Is carbon fiber even worth it anymore for 29"er wheels?

Aluminum rims have come a long way for 29"ers

Case in point: SRAM introduced some new wheels recently- the Roam and Rail wheels, (see here), and you have a direct comparison between what you get and what you don't get, (at least on paper), with comparably designed and purposed aluminum and carbon rims.

The Roam 60, a carbon rimmed 29"er wheel weighs in at 1625g, has a 28mm outer/21mm inner rim dimension, and costs $2199.00. Now the similar Roam 50, with an aluminum rim, weighs 1610 gms, has a 25 outer/ 21mm inner rim dimension, and sells for $1072.00. You can see that weight, inner rim dimension, and the cost are the three specs that jump out here.

The aluminum Roam 50 actually weighs less, has the same inner rim dimension, and is over a grand cheaper. To be fair, SRAM says the carbon rim on the Roam 60 actually weighs 10 grams less than the aluminum Roam 50 rim, but so what? (You can not buy just rims here, right?) And what's 10 grams versus saving a grand? Again- SRAM has said the Roam 60 is stronger. (Interestingly, the word stiffer was not used to describe the Roam 60 rim versus the Roam 50 rim, but I don't know that it is not stiffer.)

Well, you can argue the minutiae all you want, but the difference in price is not minute. The difference in performance? Maybe not so much, eh? It will be interesting to see, but again- Carbon doesn't automatically call out "better" here. And even if it is, by a little bit, the costs are dramatically different which seems to point to less value in the carbon format. Thinking about some of the other details on those SRAM rims brings this out even more.

And not all carbon rims are appointed or perform similarly, I get that. However; there are not too many companies making such similar wheel models in carbon and aluminum. In this case, the promise of carbon fiber seems to have a flat taste in the mouth.