Mostly recaps of two wheeled rambles through the countryside, but sometimes thoughts on other things.

Monday, February 25, 2013

Continuing On..

"So what  kind of gearing do you want? Are you clipping in or pedaling free, or something in between?  More on all that next time."

Most of the people who come out to a beginner ride will reply, when asked about their bike, "It's whatever they recommended at the bike shop."  That usually means whatever the bike shop had in stock and was trying to sell on that particular day. Like just about anything you buy, almost every part of a bike has size and quality options. There are a lot of numbers on a bike, and the number of teeth on the gear in front by the pedals and the number of teeth in back by the rear wheel governs how hard you have to pedal to make the bike move, and what the resulting speed of that pedal stroke will be. So, if your big gear in front has 50 teeth and the big one on back has 25 (a fairly common set up these days), your wheel goes around twice for every turn of the pedals. If your smallest gear in back has 11 teeth, then you spin 50/11 or almost 5 times in back for each pedal turn. Over twice as hard and twice as fast. The usual smaller gear up front (and most of the bikes I see lately have this) is 34 teeth. So the absolute EASIEST gear you have is 34/25 or a ratio of 1.36. You can count gear teeth yourself, or look at them in good light and find the numbers stamped on them at the factory. 

Here's a simplified picture of a bike's drive train. The front gears on the crankset are called chain rings. The rest of the crankset is the crank arms which the pedals attach to and the bearing that connects them, called a bottom bracket. The front derailler moves the chain from one chain ring to another. The rear gears used to be called a freewheel. (I still use these. They are threaded and spin on and off the wheel hub) These days the wheel has a spinning freehub instead and a cassette of gears (also called a cluster) slides on and off it. The rear derailler moves the chain from one to another back gear (or cog). You can shift either or both at the same time. If your deraillers are not set up right, you can shift too far and the chain goes over the inside or outside and comes off. Cables attached to your shifters move the deraillers. (The French spelling is derailleur. More and more you see the English derailler instead these days. They were invented by an Italian. He started a small parts company that is still in business.)

If you climb hills, or have a fair amount of weight to lug up any sort of slope (your own weight or cargo you're carrying), then lower gears are very helpful. I have a couple of bikes and one of them has that 50 & 34 double gearing up front (called a "compact double") and the gears in the back go from 13 teeth to 27 teeth. My lowest gear there is 1.26. My other bikes all have 3 gears in front. The 3rd is a smaller one, called a "granny" by many. So easy to use, your granny could pedal it. The small gear for me is 26 teeth. Those bikes have either 26 or 32 teeth in back. Now my effort level is even less than 1:1. A 26 to 32 gives a ratio of 0.81. That's 40% less work to go up a hill than the 34 to 25 ratio on a bike shop floor model. This really matters when you are well into a ride and getting tired, believe me. A wider range rear set of gears (called a cassette) works with a double gear set up front too, just not over as wide a range. Is having a 3rd front gear heavy? It adds a few ounces to your bike weight. Less than your cell phone probably. Or your Garmin. Or a filled water bottle. Well, you get the idea. You have make sure that the number of gears and the number of teeth of the gears you buy (if you are replacing what came stock with the bike) suits the shifting mechanism you have (unless you are changing that too). You can order your new bike with wider range gearing and the shop will set it up for you. One local rider did that when she bought her first road bike, following a period of coming out to club rides on her mountain bike. I'll be glad to help with any questions.  Yes, you travel uphill slowly in a very low gear, but you do travel and you won't feel like death at the top of the climb. As long as you keep moving, you will not keel over, either.

So the pedals go in a circle every time you push on them and each turn of the circle makes your rear wheel spin which propels your bike. If you average about 72 RPM or more, that's called "spinning." Less is called "pumping." Spinning is easier on your joints and more efficient than pumping is. So you select the gears front and rear that let you keep a desired effort level at the rate of spin (called "cadence") desired. For me, it's 84 RPM average, and I usually run 14 - 16 mph on a flat smooth road in no wind, so I want a gear ratio of about 2.36.  Yesterday, on the relaxer ride, I was coming up Jackson Ferry Rd at 80 RPM. My front chain ring was 42 teeth and my rear cog was
a 16 tooth so that was 2.63 ratio. My speed was about 16 mph. That bike has three chain rings and 42 is the middle one. I have a spreadsheet gear calculator but really, I go by what feels best at any point in any given ride. I ride "free" in that I don't connect to the pedals as a rule. You can connect your feet to the pedals by means of snap in cleats on shoes, or a metal or plastic cage that your shoe slides into or by a fabric strap that you slide your foot under. I've tried all of those methods and for me, riding is more enjoyable when I can move my feet around to relieve any hot spots or joint twinges. Also, I push in different ways when climbing than when going flat. If my feet are locked in place, none of that can happen. If you stop your bike and forget or are unable to release the foot on the down leaning side of the bike, you fall over on the ground. This is embarrassing usually and can cause injury. I know of no one who clips in to the pedals who has NOT fallen over. Including me. The attachment mechanism of any sort adds a few ounces of weight as well.

so why do so many people clip in or otherwise connect to pedals? There are two reasons. The first is that your feet won't slide off the pedals. The second is that with practice, you can pedal more efficiently by pulling UP on the pedals as well as pushing down, and even pedaling in a full circle. If your goal is to race, or even just to go faster, this is an advantage for you. In the end, I decided to adopt a more relaxed bike lifestyle and stay comfortable and free of foot, ankle and knee pain. I also can put my feet down fast when unexpected road conditions pop up. I still pedal in a smooth circle and actually apply force through about 2/3 of the pedal circle. Push forward, then down, then draw back. I can't pull up of course, but by lifting the idle leg, it makes the pushing work of the opposite leg easier.

We had 12 riders including 4 brand new faces yesterday for the relaxer outing! Once again I heard how painful a tush-cush saddle is. Yes, it is. Please see the prior entry for comments on saddles. I rode in un-padded pants on an un-padded leather saddle and was pretty happy about it. That's because the leather saddle has shaped to fit me and my weight is evenly distributed on it. There are any number of saddles out there to try of course and comfort is a very personal decision. Since it's really the most important part of bike comfort, take your time, try lots of saddles and saddle positions (nose up, flat, down, etc) until you find the combination that yields an enjoyable ride every time. You'll ride more that way.

Century season is coming up. I'm thinking of doing 4 in the Alabama "Backroads" series this year. Plus the MS 150 (for the 11 year running). We'll see how it all pans out.


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