Big Ringing It

 The efficiencies of cycling are discussions worth having as we are all limited to a very small amount of power output and maximizing that is important to cyclists who want to enjoy riding for as long as they can. It isn't just for racing. 

I've been observant of what makes cycling easier (more efficient) without resorting to gimmickry or assistance for years. Yes, you can find all sorts of quackery which promises efficiency gains. You also can bypass all of this and get an e-Bike where a lot of the efficiencies for 100% human powered cycling are of no concern.  

I'm not talking about those things here. I'm speaking of things I've learned and which are validated by testing by racers and companies involved in performance cycling. One thing which triggered this post was an inteview of SILCA's Josh Poertner, CEO of the company and who routinely works with top pro cyclists in road and gravel disciplines. 

I wish I'd have paid attention to the site/channel who did the interview because I'd link it here. Josh was spitting some knowledge with facts to back it up. The things I knew inherently to be true from my experiences and observations. Plus he had a bit on aero wheels and tires I found enlightening.  

First, I have read before, and Josh reiterated the fact, that big rings and cogs are more efficient than smaller ones. So, that 10T cog on your SRAM cassette? Highly inefficient. This is why Pro road riders have jacked up their big chain rings and cassettes,  Josh claims many of those cassettes for the Pros are custom assembled for 12T small cogs and up from there. All with an eye to keep the chain as straight as possible in races where flat terrain or time trials are going to occur.  

This is also why many Pro riders prefer 2X set ups. Especially if they are going to be using the entirety of the cassette. That way the chain can be kept as straight - and thus efficient - as possible. 

Cross-chaining, normally thought of as a double or triple crankset thing, is a huge deal in 1X set ups. The single front chain ring has some advantages, but chain efficiency is certainly not one of them. The 1X does allow for bigger tires on MTB's, gravel bikes, and it does allow for full suspension designs which would not be possible if a front derailleur were necessary. However; most of us gravel folk don't need  1X and would benefit from 2X crank sets more than we would 1X. 

Then Josh shared what he has found to be the "fastest" chain. I was not surprised to hear him say it was a Shimano Dura Ace chain. That's what I use on some of my bicycles, or an Ultegra or XTR chain, which are all proven to me to be superior chains to anything SRAM has ever made. But I was surprised to hear the fastest chain wasn't something else. So that was news to me. I would not have been surprised to hear Josh say that a KMC chain or maybe a Wipperman chain was better, but he claims it is Dura Ace, and I'm inclined to believe it based upon what Josh does for testing. 

Image courtesy of Corima

Finally, the aero thing for gravel. Josh was saying that wind tunnel testing is showing that if your gravel tires are wider than your rims then whatever the depth/aero profile is of the rim pretty much gains you little. There are watt savings, but they are minimized by that big tire. 

This makes sense to me. Josh was saying the airflow off the tire has to flow off the tire seamlessly to the transition to the rim for the best aero gains. He claimed the rim should ideally be slightly wider than the tire, to gain the maximum efficiency in aero. 

He went on to say that if you are using a big tire all rim depth really does on most gravel set ups is shorten the spokes. Interesting.... 

Then additionally on the wider tire thing. Josh is saying wider is better if terrain/road surfaces are rough. Okay, I've seen this said as well from several sources. However; when gravel racers start running MTB width tires my eyebrows raise. At what point does tire/wheel weight start to erode gains from wider tires? 

Yes, there are light, wide-ish MTB tires. However; how much less efficient is a lighter, 45mm tire and is that narrower tire actually gaining back watts from aerodynamics? I'm not seeing these two things being connected nor discussed. My inclination is to say wider tires are better on rougher roads to a point, and then tire weight and aerodynamics start to take away any benefits you gained from rolling resistance. Or.....maybe I'm nuts? 

Anyway, it's all stuff that matters and maybe if you are wanting to see the best gains from your equipment which would enhance your riding, these are things to consider.