jeff44

I recently swapped a Campy Veloce 10 speed alloy crank for a Centaur 10 speed crank with carbon fiber arms. I rode the bike (15 year old Ritchey Logic) with the carbon crank for the first time today and was actually faster than before on a 17 mile loop I ride often. Is it possible the carbon crank transfers more rider energy to the bike versus the alloy crank? There may be a 1/2 pound difference, if that, between the two with the carbon being lighter. Maybe this is my head wanting to go faster to justify the cost!

Your comments would be appreciated.

Jeff

FBinNY 

To set the record straight, it's between CF and Aluminum (not steel).

I suspect that the biggest difference was that you were feeling your oats today. IME incremental mechanical improvements and/or lower weight do help improve performance, which is why people do so, but only incrementally.

Decades back when I sponsored an amateur team, we found that we could squeeze better performance out of certain riders simply by describing the work we did on their bikes. We didn't actually have to change anything, just convince them that we did and it would help.

The Placebo effect is real and should never be discounted when people have a better than normal ride after some change to their bike.

Spaghetti Legs 

Clearly if that is the independent factor the new cranks made you faster.

In truth, probably not, other than the excitement of riding with new bike bits. I doubt you saved that much weight, I would guess maybe 1 to 3 ounces (100g). I'll leave the argument of power transfer of aluminum vs carbon to others with stronger opinions. Did you put a new bottom bracket on too?

RoadLight

Hi Jeff,

If you were outdoors, I imagine that the wind over the 17 mile loop would have had a much more significant effect than the crank, alone. In addition to the psychological gains of riding with a carbon crank, the wind may have been more favorable on that day.

When I first started riding seriously, it was on a quad-butted steel Fuji road frame from 1985. Just about everything else on it was aluminum and it had a Suntour alloy crank. I still have that bike and use it as a "work" bike when I need to haul stuff or pedal to the other side of the park. But I upgraded a while back to a newer Fuji road bike with a carbon frame and fork, carbon seat post, carbon handlebars, carbon aerobars and a carbon crank. I started with a SRAM Force 2x10 crank with carbon arms and spider but recently upgraded to a SRAM Red 2x11 crank which I converted to a 1x with a SRAM X-Sync chainring and removed my front derailleur. I even removed the obsolete shift paddle from my lever. I'm still using the 10x rear whose derailleur is part carbon, part aluminum and part titanium.

The point is: It takes many incremental changes to add up to big improvements in performance. My average speed (over many, many rides) is 2 mph faster with the carbon rig than my vintage steel rig over the 35 mile loop that I regularly ride during training. And that's not the only reason. I weigh a little less, I can hold a more aerodynamic position on my carbon rig and my strength and endurance have increased, too.

Making steady improvement is a two-sided proposition. First, you need to understand the "big picture". What will provide the biggest gains? The answer is almost always "you" rather than your bike. Second, you need to pay attention to the details. This involves understanding where the greatest gains for your dollar come from. Also understand that improvements to the bike is a pursuit of diminishing returns. The better your bike, the more it will cost to improve it and the less improvement you'll gain for that cost. That's the way all tech goes. After you've picked the low-hanging easy-to-reach tech fruit, it gets much more difficult and "expensive" to go higher because you've already exhausted the easier/cheaper solutions.

Can a carbon crank help you improve? Sure. I wouldn't give up mine. But it's a choice that's best made after you've tackled some of the bigger issues. But there are always exceptions. If your old crank breaks, why not replace it with a better one? It might not have been the next component that you had planned to upgrade, but necessity moved it higher up the list. And there's value in aesthetic choices. Some of the carbon parts just plain look better and if you feel "good" about your ride, you may just ride "gooder", too. :-)

Kind regards, RoadLight

andr0id

You have discovered a well kept secret of the pros.
The only thing faster than black CF cranks would be red CF cranks.

Squeezebox

Crank lengths?

Jarrett2

Did you change out the bottom bracket as well or have it serviced during the process? If so, maybe the new bearings are more efficient than the old?

Aside from that, I think you might have just experienced "New Bike (Part) Fitness"

I tend to have one or two really fast rides after I get a new bike (or part that I think might make a magical performance difference) then back to my same old speed

fietsbob

Bullseye made some well regarded steel crankarms , hand welded from Chromoly , box tube arms

His patent included having a tube spindle as Part of the right crankarm .


Carbon will be OK just replace it every year or 2 .

Have to stay on the cutting edge ? you want to do that to keep up.

AlmostTrick

CF crank arms are faster... until they snap.

Jarrett2

I was going to put a carbon fiber crank on my latest road bike, but my trusted bike builder suggested skipping them for Clydes. He said he personally knows a 250+ lb rider that has snapped two arms off carbon cranks and switched due to it. I opted for alloy based on that feedback.

well biked

You'd never ride that 17 mile loop and do it in the same time twice, so my thought is that you just happened to do it faster this time.

dabac

Never seen a snapped CF crank (yet). Seen some where the threaded insert for the pedal has come loose though.
But I have seen some snapped aluminium cranks.
Although what tops the list of witnessed failures in that area these days is snapped HTII BB axles.