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Just wondering what all people have as their gear ratios. I ride lots of hills so I have a 46:16 (2.9:1).
 

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Road = 53:20
Mtn: anywhere from 32:20 for the steep rocky stuff to 32:16 for flowy rolling singletrack.
 

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I have used such a ratio since age 15 and have ridden 50 miles at a time including many steep hills and descents on such a bike.
I ride in some open areas near the coast. Wind is more of an issue than hills. 48x12 is not something I'd want to get caught with fighting 35 knots going home. I think a strong young guy could handle that, but I'm not so strong anymore and have always been a spinner. Big, long gears kill me. 48x18 and no more.
 

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55x14-13-12 on flat trial course as per distance.
52x15 on hill climb race under 7% average
50x16 on hill climb race under 11% average
48x18 on hill climb race over 11% average grade.

I'm somewhat old school on hill racing. Most UK hillers now use gears. About 20% do not. I like the weight saving and the threat of failure. This make a lad work as hard as he should.
 

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retromike3
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gear ratios?

I'm used to gear inches. If you divide the chainring number by the cog number and then multiply by the diameter of the rear wheel you get how many inches you will go in one revolution of the peddle. I like running a small gear, something like 65 inches. But I'm a fat old guy.


Mike Frye-the bike guy:cool:
 

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I'm used to gear inches. If you divide the chainring number by the cog number and then multiply by the diameter of the rear wheel you get how many inches you will go in one revolution of the peddle. I like running a small gear, something like 65 inches. But I'm a fat old guy.


Mike Frye-the bike guy:cool:
Mike, I like to think in gear inches also, but you're off a bit. That number you come up with after doing your formula represents the old fashion Pennyfarthing big wheel diameter. Example: 50x15 gearing = 90 inch gear if using a 27 inch tyre. That 90 inches is what a Pennyfarthing's wheel diameter would have to be in order to equal a modern 50x15 with 27 inch tyres.

Distance traveled is gear inch (90 in this case) times 3.14. (circumference of wheel) You get 282.6 inches of travel for one turn of the pedals. That's about 23.55 feet per pedal turn.

Think of that one turn of the pedal of your modern bike in 50x15 as equal to one turn of the pedal for a Pennyfarthing with a giant 90 inch front wheel.

Hope that's been made clearer.

Now to further muddy the creek, take that 23.55 feet of travel per pedal stroke and multiply by cadence. Say 90 rpms. 90 x 23.55 = 2119.5 feet of travel per minute. You've gone 2119.5 feet in just one minute. Now multiply that "minute" distance by 60 to get your distance traveled in an hour.

2119.5 x 60 = 127,170 feet traveled in an hour. Divide by 5280, which is a mile, and you have your miles-per hour-figured by cadence and gear.

127,170 divided by 5280 = 24.09 mph. If you can maintain a 90 rpm cadence with a bike wearing 27 tyres (700s) and geared 50x15, you'll be going 24 mph.

Mike, back to your 65" gear. Assuming a 700/27" tyre, you will travel 204.1 inches per pedal cycle. That's 17 feet. Let's say you only turn 60 rpms. That sends you 1020 feet per minute. Times 60 minutes = 61,200 feet per hour. Divide by 5280 (mile) and you are traveling 11.6 easy miles-per-hour. Crank it up and go faster. At 90 rpms, you'll be around 17.4 mph. 65 inches of gearing is a very useful sizing. You can do quite a bit without killing yourself.
 

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i usally run a 39/17 with a 180mm crank on my rides.
 
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