Aluminum v Carbon Rims for an 'Allroad' Wheel Build
 

As I am getting ready to start piecing together the components for my incoming Bingham, I stumbled across this article and it got me thinking.

My use case is a bit different as I will be more in the 70/30 road to gravel split, but I was curious if anyone other than the author above had insight on the ride feel of carbon v aluminum wheels on the fatter tire disc builds.

If you go off-road, ya gotta pay to play so keep replacement rims in mind

M

I have used Belgium+ as a gravel allroad wheel and loved them. I currently have Reynolds carbon wheels on both of my gravel bikes and love them, but I do cringe sometimes when riding through leaf covered rocky trails. They have held up quite well so far, but I do not recall having the same feeling when running the Belgium+.

After seeing the condition of my ksyrium all road rims after two years of riding mostly road but also a number of miles on gravel and single track...

Dents, huge scratches and gouges in the bed of the rim - these surprised me as I never really thought I was hitting the inner rim that often on rocks, and all over the external areas as expected.

I don’t think I’d ever consider carbon for gravel riding unless someone else is paying.

Something to keep in mind is that a narrower (typical with aluminum) rim not only flexes more in torsional deflection (that is the precurser to potato-chip failure mode), but that the narrower rim makes the tire more supple by altering both the shape of the contact area and the angle of the sidewalls meeting the rim.
Additionally, the reduced OD of the tire casing reduces casing tension at any given psi.
So all told, there are FOUR reasons why a (typically narrower) aluminum rim might make for a softer-feeling ride.

And it's not just the inside width of a carbon rim that contributes to a stiffer ride, since the outside width is usually greater yet due to thicker rim sidewalls, which presents the flexing tire casing with a wider area off of which the sidewalls must rest under larger localized tire deflections.

So I think that makes five reasons, which cumulatively may be significant, two of which (outside width and torsional stiffness) are to varying degrees independent of the exact inside width.

I’m running the HED Belgium+ Eroica on my Bingham. I was comparing the weight vs some of the comparable carbon rims and it actually seemed pretty negligible in terms of difference. I wouldn’t hesitate to go with the Belgium+ for an all road build, if you’re leaning that way.

As a leading "ride gravel bike inappropriately" contender, I'd say carbon for sure. Rock gardens, baby head stream crossings, deep rail road ballast.. carbon just bounces stuff off with no damage, aluminum gets dinged and bent up. After 10,000+ abusive miles, the carbon rims are scratched up but still rocking.

Also make sure you're running tires about 1 cm wider than your rim OD, that will help protect the rims.

Or it catastrophically fails (that’s dramatic for no longer being usable after identifying cracks) which is what happened in my case though I’ll admit it wasn’t the wheels that hit rocks but a handlebar and frame (not at the same time :))

The handlebar was perhaps a bad example as i understand they probably aren’t designed to take hits from the side.

The frame though was a mountain bike and a rock jumped up and ruined the down tube.

splitting hairs.

I've got a set of aluminum (Easton R90SL) rims on my CX/gravel bike and they've been pretty bomb proof over several seasons of road, gravel, singletrack and generally not being nice to them. I finally dented a rim at Monster Cross this year (stream crossings... ) and had it relaced with new nipples and rims. Maybe it would have survived longer if carbon, but, I'd need several more rim replacements before I approach the same cost of using carbon rims.

Another thing to consider is the roads/off roads you will be riding. Baby heads and rock gardens - for me that sounds more like mountain bike territory than gravel, and you say 70/30 road so .....

No real weight savings with carbon (indeed you may be gaining weight compared to a nice alloy wheel) unless you spend $$$$. Do you need the aerodynamics of a deep rim? Do you want a really stiff rim? Is it going to matter much with big tires with high volume and low pressure?

I think only you can answer these questions but I wouldn't shy away from alloy just cause carbon is the new hot thing on the block. For example, Boyd Cycles makes some nice alloy wheels - Altamont, Altamont lite, the new CCC gravel specific design rim - I've had very good experiences with his wheels.

Ccc replaced my ksyrium all road. They are soooo much better riding with higher volume tires and easier to mount and seal the tires.

What are these wheels?

I have run one HED C2 wheel set and two HED Belgium Plus wheel sets on three of my bikes with no issues.

I don't see how you can beat the value for the dollar and reliability of a HED Belgium Plus rim brake wheel set with Chris King hubs for $1,000. Check out the Chris King website for other options like disc brake hubs for a bit more money.

I am 5'10" and 190 lbs and am fairly hard on wheels since I have no aerobic capacity but plenty of fast twitch muscle. No issues with my HED Belgium rims going out of true, cracking at the nipple, developing hops or turning into a potato chip.

Hope your bike build turns out to be everything you want it to be!

Not OP, but I'm eyeing a set of Belgium+, exactly as you described (CK hubs, disc brakes). I see they're $1,215 on CK's website. Do you know if these wheels ever go on sale? If not, I might just bite the bullet and buy them from my LBS.

https://chrisking.com/collections/he...isc-r45d-28-28

Oh, these are light-bicycle rims 35 mm deep, 25 mm wide. 28 hole, CXray spokes, laced to DT240S hubs. But I imagine any non-ultra-flyweight carbon is going to be equally durable. I don't suggest anyone ride the things I ride on a gravel bike, because it is dumb, but I definitely torture the poor thing. :)

I've destroyed a set of A23 alloy rims with a single trip through a marginal section, which could be just bad luck. But alloy doesn't seem to like sideways dings by rocks.