Cycling and What You Need to Know About Carbon Fiber Rims and Wheels.

I’ve got approximately 40,000 miles on this bike:

I’ve ridden it, almost exclusively with aluminum wheels, for upwards of eight years. It was only recently I decided to fit my good wheels to the rain bike for DALMAC.  It’s a long story, but I thought I couldn’t get 25mm tires and 23mm (wide) rims to work with the frame clearance I had on the old 5200.  25’s on my alloy wheels rub the chain stays – there’s no clearance.  With the wider carbon fiber rims, though, I was mistaken.  The extra width of the rim changes the profile of the tire, therefore allowing 3-mm each side of the tire betwixt the chain stays – enough space.

I did need new brakes, though. The old calipers wouldn’t take the wider rim, so I picked up a set of 2019 Shimano 105 calipers for the ’99 frame. I fitted the new wheels just a week before the big tour – just enough time to give them a roll to make sure everything was good…

I rode the new setup for a week before the big tour, then for the 377 mile weekend.

First, I was riding Specialized Turbo Pro 24mm tires pumped to 112 psi on the aluminum wheels.  I’ve got 25mm Serfas Prototype tires on the carbon wheels and I pump those up to 107 psi (lately).  There might be a little bit of difference in suppleness between the Specialized and Serfas tires, but it wouldn’t be much and the edge would absolutely go to the Specialized tires, if a difference exists.

With that out of the way, carbon fiber wheels are exactly what you’d think.  They’re faster and they improve ride characteristics.

Staying with subjective data, because I don’t have a testing facility other than open roads, my legs and my heinie, understanding and quantifying the improved ride quality is fairly simple.  If you’ve ridden a bike with an aluminum frame and another with a carbon fiber frame, you don’t need a $40,000,000 testing facility to know that the carbon fiber frame, all things being equal, will be a more comfortable ride that the aluminum frame.  Well, the same improvements in feel apply to carbon fiber wheels.

While some people want to make this into rocket science, I don’t think it’s entirely necessary.  There’s certainly room for completely geeking out over testing data, but all one really needs is to ride one a lot, then switch to the other.  You’ll feel the difference immediately.

So, while I would owe some improvement to the 1mm difference in tires and the extra five psi, the difference would be minimal at best.  The interesting twist happened when I swapped wheels back on returning from DALMAC.  All of a sudden I could feel every bump in the road riding the 5200.  I’ve found that when ride quality is improved, for whatever reason, the benefit slowly fades to the background as time goes by.  This happened on my tour.  So it was a pretty big shock going back to the alloy wheels.  I just might have to try lowering the pressure in those tires a little bit.  The difference between wheelsets was surprising.

Simply put, if you can afford a set of carbon fiber wheels, they’re worth it.  The aerodynamic improvement, even of a 38-mm rim over, say, a 23-mm, is well documented and make the wheels easier to keep up to speed (above, say 20-mph).  The ride quality improvements are equally impressive, if not more so.

To wrap this up, carbon fiber wheels won’t give you an edge.  They won’t make you faster.  They won’t take you from a B Group rider to an A.  They make fast a little easier.  If you want to jump groups, you’ll need a heaping helping of “want to” before you start worrying about which wheels you’ll buy.  On the other hand, there’s no question, a set of carbon wheels sure takes some sting out of the road.