coppercook62

I ordered a custom pair 2 weeks ago.

Super D

Weight-wise, I was looking at shoe pair weights 200-250g apart (reasonable range from low to high) and dividing in half for the per shoe weight, just for discussion purposes. That's around a quarter pound per shoe. Carbon soled shoes tend to be on the lighter side, non-carbon tend to range on the heavier side. Not being specific here, weight is published for shoe pairs and there are definitely plenty of light shoes out there, with carbon soles saving a fair amount of weight. If all of the shoes in consideration are carbon or CR, and weigh in the 400-550g per pair range, I'm with you, that's negligible. The higher the weight, the more rotating mass is a factor over time.

In terms of data and reasoning why shoe manufacturers produce lightweight, stiff carbon-soled shoes for performance and racing applications, I would disagree, but I'm not a lab tech, testing shoe engineering. In my firsthand experience using athletic shoes w/cages, then flexible cycling shoes w/nylon soles and then upgrading to stiffer CR shoes, it created an immediate power transfer difference, lessened strain in my feet on long rides, and I never went backward from that point. In terms of data, I'm sure the shoe manufacturers each create their own testing modalities during shoe engineering and development, but if you want to look at some really old data from the beginning of trending toward carbon sole application, there are articles online from over a decade ago that showed higher pressure measured in the forefoot on the pedal imparted by carbon soled shoes vs more flexible nylon. The thing is, power isn't being applied to the ball of the foot and then to the pedal in a straight line; it's being applied by a lever (the foot). If you rode with cages and athletic shoes, I'd wager you'd feel the immediate strain on your feet and the energy being absorbed by your flexy lever (unsupported foot) just like I did back then. If you can buy that concept, then moving on to nylon vs CR vs carbon soles, it's just a firm lever which is transmitting pressure with less deflection (depending on material and thickness). The more the lever flexes, the more energy is turned into heat or deformation of the shoe, and while some is returned, it is conserved more if there is less initial deflection. You said it's returned to the system; well, that depends on the material, how much and the engineering of the lever. I could put a paper thin carbon sole on a shoe and it'd flex like a rhythmic gymnast, and while some energy would be returned, some would be lost. The shoe manufacturers are gaining stiffness at a lower weight and absorbing less energy with carbon over other materials currently. Is it negligible? It depends.

An analogy is a racing ski boot versus a recreational ski boot. They're both far stiffer than a naked foot or soft boot, and create a tremendous amount of leverage. Racing boots tend to utilize materials that transmit physical inputs to the cuff, tongue, sole, binding, and ski quicker in order to affect directional changes and apply power with less variance, and less time from the initiation of the input to the reaction of the ski. Recreational boots are created to deflect more, forgiving imprecise movements, and reacting more slowly for a developing skier. Stiff lever leads to max energy transfer (and faster), more flexible lever leads to lower energy transfer (more energy lost) and the transfer is slower (it takes more time for the exchange to complete).

Now, I'm with you on this part in spirit. Why is there no easy-to-find data for our shoes from right now, this year, on how much more efficiently a shoe of whatever material transfers power, and how that translates into efficiency on the bike? The manufacturers sell carbon soled shoes touting power transfer efficiency, so where's the proof? Well, I can't answer that. I think there should be too. I'd certainly think that each carbon soled racing shoe is going through extensive finite element analysis pre-production, and the shapes, thicknesses, weaves, and filaments in those carbon soles are made very purposefully (just like skis). Why don't carbon bike frame manufacturers publish all of their data? Some have, but not every year...It's a bit of a crap shoot for us regular consumers, isn't it. We have to test out gear and make a pick based on little data. Like I said, I'm with you on this.

What I will say is that I'll err on the side of getting a stiffer support under my levers (feet), and keeping rotating mass to a minimum. More rotating mass and a more flexible lever doesn't make sense to me if I'm trying to get the most out of what my body can produce on a given ride. I expect a lighter stiffer soled shoe will equate to less fatigue over 60-80 miles than a heavier softer soled shoe, just based on what I've used in the past and with no data in hand to help me decide how I felt.

Geez, that's too many words, sorry. I think at this point, I'm not up to arguing, and would just say that everyone should get what makes them happy, and we're all right as long as we meet that criteria--even if it's hokus-pokus bs and we're paying for nice shoes for no good reason, and we're creating minimal gains. I'm still going to get pretty light carbon shoes, and I don't care if I'm overdoing it. It makes me feel good, just like the light carbon bike does. It's fun getting really good stuff and riding the hell out of it.

kleng

I tried the cx236 , the heel cup is too loose for me and the toe box is too tall and roomy, you feel it on the pedal upstroke as your foot lifts inside the shoe. I went back to SH-R320, which can be moulded and fits me better

gregf83 

I think you probably need to ride more and write less Regarding rotating mass, other than the weight it's a non-issue for anything other than acceleration and even there an extra 1/2 to pound of weight on the pedals isn't material. It's not too difficult to calculate the amount of energy stored in a set of shoes rotating around a crank and the energy is very small. The amount of power required to spin up the pedals and shoes would be measured in tenths of watts.

Saving 1/2 lb on your shoes will save you about 10S on a one hour hill climb.

Super D

You are wise, good words to follow.


That's not a lot to worry about, thanks for that.