I’ve been riding for long enough to know that what “feels” good and and what “is” good in terms of technique are two independent sets with a small intersection; it’s very important to put a lot of thought and research into what you’re doing to make sure it offers a benefit. Research takes “work” and “time”, so I’m not very fond of that approach. Instead, I like to do a lot of “thinking”, leveraging both my inadequate expertise in mechanics and my unusually high degree of confidence in my ability to reason in order to jump to conclusions that benefit my initial assumptions.
For example, I believe there is an advantage to riding sur la plaque, or in the big ring, as opposed to riding in the same size gear on the small ring. I generally find that when I’m strong enough to stay on top of my gear, climbing in the big ring feels less cumbersome than when I climb in the small ring at the same speed. The downside is that it is like playing a game of chicken with your legs; it works very well if you are able to keep the gear turning over smoothly, but should you fall behind the gear, and your speed evaporates as you fall into a spiral of downshifting and decreasing speeds (not to mention morale).
All this can be explained away by having good legs or not (un jour sans), but I think there is a mechanical advantage as well.
First, there is the duration of the effort. As they say, it never gets easier, you just go faster, but I firmly believe faster is easier, provided you are strong and fit enough to support the effort. The faster you climb, the less changes in gradient and road surface impact your speed. Not to mention that while all athletes perform the same amount of work when they cross over the same climb regardless of the duration of their effort, athletes doing so in less time suffer for a shorter period of time than do those who go slower. Marco Pantani claimed that despite knowing the suffering that was just around the corner before his attacks, he was motivated to go as fast as possible in order to make the suffering end sooner.
Second, there seems to be a mechanical advantage of riding in the big ring. I’m a little bit hazy on the physics here, but it seems to me that the crank arm is in effect a second-class lever and, while maintaining the same length crank arm (lever) and fulcrum (bottom bracket), by moving into the big ring, you are moving load farther out on the lever, providing a mechanical advantage over the small ring.
WikiPedia defines leverage as:
load arm x load force = effort arm x effort force
In our case, since the speed is constant, that means that the load force (to turn the pedals) is also constant. And, since the load arm (crank) is a fixed length and the effort arm length is increased when moving the chain to the large chainring, the effort force is reduced in order to maintain a balanced equation, meaning that it doesn’t just feel good to ride sur la plaque, it actually is good.
All that said, this theory completely ignores the energy loss of bending the chain as you start to move the chain from straight at the center of the cassette towards the edge of your cassette, in particular when riding in the big ring and crossing to bigger cogs. Q-Factor has an impact on how much your chain is bending as you ride in bigger and bigger cogs, but I think there’s a measurable loss if you are crossing your chain completely (big ring to biggest cog); and I suspect is is entirely possible that the big ring’s mechanical advantages are outweighed by losses in chain friction.
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I'm a massive girl. And I'm running a compact.
But I'll get my excuses in early. I'm coming back to cycling after 14 years off the bike following a broken neck. I started riding again in December last year and I'm riding l'Etape in July. On 6 months of very random training.
If that doesn't follow rule 5 I don't know what does, so I'll ask for a temporary rescind of the no compact rules here. I do have a lovely FSA carbon 53/39 set up in shed for the months ahead.
In a funny way it does not matter. I mean were talking about gears and a 89 inch or 49 inch gear is the same on a compact or old school 42-53 so it (as said above) is what you do with it, I am not coming back like Guy, or at least not from a huge disaster like his, my sin was getting old and fat so I am happy to not have the choice. Will I have a compact someday? Probably, but I hope that's the day I wake up and say "gee that recumbent look like a really intelligent way to go get my beer".
@rob
It does matter.
It may be that the the gear ratios on a compact or a "normal" are the same. But it's how they are used and how they are available. Compacts might have a more useable range of gears, but it means that when you shift between rings you have to shift a load at the back and your momentum disappears. The little ring on a compact is only any good if you're going up hills, the rest of the time you're in the big ring.
In my book, little ring is for climbing and easy rides and the big ring is for training and racing.
@david
why so protective of triples? If anything they are worse than compacts
@Jarvis Jarvis I am sure you are right but the bottom line is what happens on the road and I see no difference with my shifting pattern compared to my mates in terms of "results". In fact $9000 bikes, oh wait we now have the new electric shifting in my group (holy!!!!) and spinning hill climbing (and I like to spin with the best) are not dropping my fat ass that often?
So does it really matter or is this just another hollow discussion about preferences? I do not know. I am going to keep with the 42 until my leg can't turn her over or if I move to where there are serious hills and then it makes perfect sense!
@David "But I'm all for a Rule on compacts. It is a matter of style. A matter of protecting the history, traditions, and culture of the sport against the wicked forces of capitalism."
Well, going on that logic, you should be riding a steel frame with a threaded headset and quill stem, square taper BB and downtube shifters for your 6 speed cluster.
If you have a carbon frame with 10 speed and aero wheels, or even just one of those, then you've just contadicted everything you've said about compacts.
@Jarvis No, no. I meant triples are so bad, even so much worse than compacts, that we do not even need a Rule against them.
That doesn't follow! If new innovations truly make you go faster, stronger, harder, then buy them. I am, however, condemning the widespread distribution of compacts on stock bikes in bicycle shops. Their legitimacy is so narrow in range that they should be for special order only. I mean, if you are recovering from breaking your neck and you can't avoid hills . . . or, if you are Liquigas rider who has to time-trial up the Plan de Corones, fine. But to sell a budding young cyclist a compact . . . well, I say it's a freakin' crime against the Cog.
(Did you sell young Nathan his compact??)
@Nathan Edwards Chris Boardman putting a compact on one of his bikes. What the fuck is the world coming to?
How does an A-Head system make you go faster?
Are you saying the LeakyGas riders who used compacts up Plan de Cojones are soft? Shouldn't they have just taken a dose of Rule 5 too?
If standard chainrings are too hard to turn over up a steep hill, and a compact means that you can turn the pedals more easily, then surely that equates to going faster up that hill, no? That's why we see Pros using compacts, 28t cassettes and shit, even some triples on Angliru in the Vuelta in 99.
We are not Pros... the compact is one of the best innovations for the average cyclist in years. By your logic also, the 39t ring is also a crime against the cog. Taking it to the logical conclusion, you should be riding around on a fixed gear, and flipping your wheel around every time you get to a hill.
@brett: "Taking it to the logical conclusion, you should be riding around on a fixed gear, and flipping your wheel around every time you get to a hill."
Ouch. That hurts, brett. I think it makes sense for the LeakyGas riders to use a compact up the Plan de Cojones. The thing has got 24% grades. The winner up it this year, Garzelli, said he used a 34x29 on the steepest portions. Wow. You want the gearing that will allow you to turn over the pedals smoothly and efficiently. brett: "We are not Pros." Exactly. If you are a pro racing up 20% grades, a compact, or a 28t gear with a 39 makes sense. If not, then not. Young Nathan says he's got a 5% grade in Durham. Jesus Christ. A decent cyclist can ride up that with at 39x21 or 39x23. Selling him a compact just means, as Jarvis has said, kind of, that he's paying to go slow.
There's a wicked climb out here, in CA, "Mix Canyon", with a full kilometer at 20%. Chris Horner won a race up it about 6 or 7 years ago, by using a 39x28 rather than a 39x27, which everyone else had. All the power to him. He did what was needed to win.
The 39t ring is not a crime against the cog. Science has shown that high cadences on climbs is better than the old, slogging, climbing we saw 20 years ago with the 42. And, as I mentioned, if the Velominati are about style and aesthetics, then they have to be for the 39, since climbing in it is far more graceful and elegant.