Gears

[potsy]

Ignorant and proud of it...

I've found my new signature

 

[Arch]

It's just that I've never needed to know, so I haven't learned them. I could work them out, but I don't need to, and I have enough trouble keeping stuff in my head without filling it with other stuff...

 

[Klaus]

Not everyone wants to get stronger. Some of us just want to get from A to B, faster than walking, in relative comfort.

Getting stronger will come anyway, there's no need to go and make yourself hurt.

Klaus - find the rate of pedal spinning (it's called cadence) that feels comfortable for you. Then use your gears to try and maintain it as near as possible. So, higher downhill, and lower uphill. That's all there is to it.

Unless you're somewhere very hilly, you'll probably find you only need to use the sprockets (the gears at the wheel end) - I use 3 or 4 gears on a regular basis. I save the chainrings (the ones at the pedal end) for the more hilly bits.

I live in one of the most hilly towns in SE England, High Wycombe, however, I am only concentrating on the flat bits ....
Thanks for the advice!

 

[Debian]

I live in one of the most hilly towns in SE England, High Wycombe, however, I am only concentrating on the flat bits ....
Thanks for the advice!

OT.

I used to live in High Wycombe many moons ago, quite liked the place. Used to go cycling in Hughendon Park at dawn most days. Wish I'd never moved away in many respects.

What's the place like now?

 

[Randochap]

This thread is a prime example of why I warn on my gearing page: "If you already think cyclists are an argumentative lot, just bring up the subject of suitable sprockets."

 

[Debian]

Sheldon was of the opinion that spinning = good and pushing = bad, which I must admit is my opinion also.

High or Low?

"Higher" gears put more resistance on the pedals. If you select a gear that is too high for the conditions, it will force you into a slower cadence.

Pedaling slower than your ideal cadence is wasteful of energy. You also run a higher risk of muscle strains and joint damage, particularly to the knees and hips.

"Lower" gears make the pedals easy to turn, so it becomes easier to spin to a fast cadence.

Pedaling faster than your ideal cadence can allow you to generate an extra burst of speed, but you will tire yourself out too soon if you try to maintain an excessively fast cadence.

The Perfect Bicycle

If you had a perfect bicycle, with an infinite number of gears, you would always be pedaling at the same cadence, with the same amount of resistance to the pedals. Of course, the bike would go slower uphill, and faster downhill, but your legs would not know the difference.

Inexperienced cyclists often pedal at a cadence that is too slow, (too high a gear.) They sometimes think that this is better exercise, because they have to push harder on the pedals. This is an illusion.

Power lifting or swimming?

Consider two very different types of exercise: Power lifting vs. swimming. After you have lifted the 200 LB barbell half a dozen times, you go take a shower--high force, few repetitions. Swimming, on the other hand, involves very little resistance--you are only moving your hands and legs through water--but with many repetitions.

"Pushing" vs. "Spinning"

"Pushing" a high gear at a slow cadence is like power lifting. It is good for building up muscle mass and bulking up your legs, but it does little for your heart or lungs, and you can hurt yourself if you overdo it.

"Spinning" a lower gear at a rapid cadence is more like swimming. The rapid motion, with many repetitions makes the legs supple and flexible, it is highly aerobic, and the light pressure that goes with this style reduces wear and tear on the joints. With practice "spinning" becomes easier and more comfortable.

 

[jimboalee]

Power for speed is independent of gear ratio. The faster you want to ride, the more power you need to put through the rear hub.

There are many books out there about cycling cadence and gearing. I have yet to read this in any one :-

(Torque x RPM) / 9549.3 = Power

(Nm x n) / 9549.3 = kW

Now study this equation. If there is a power requirement to ride at a certain speed, you could either pedal fast with low torque OR pedal slow with high torque.

Get a free day in a health club. Sit on the gym bike for several hours pedalling to achieve a variety of ‘steady state’ power outputs, noting down the rpm where you ‘feel good’.
No-one can tell you how fast to pedal, its for YOU to find out.

There are on the internet several ‘cook book’ curves of speed vs power for cyclists. Have a look at them and compare your power breakpoints to get an estimate of the speed you would be riding.

You have now found out what cadence suits you for various roadspeeds. Now its time to calculate some gear ratios which give you YOUR cadence for YOUR favourite roadspeeds.

What could be simpler?

PS The interesting bit is where you try to 'steady state' 325, 350 and 375 Watts.

 

[jimboalee]

This thread is a prime example of why I warn on my gearing page: "If you already think cyclists are an argumentative lot, just bring up the subject of suitable sprockets."

I'm in for the duration. Send out for a pizza.

 

[Bill Gates]

If you are taking one moment in time then sure enough your cadence to produce the required level of power for any given distance or time may be relatively high or low.

E.g one hour riding could be 75 or 100 rpm depending on the individual.

Now that one moment in time could be a rider with 6 months riding experience or 1 year or 3 years or more than 5 years. The question for me is what is the most efficient cadence that any of these riders should aspire to in order to reach their maximum power output all other things being equal.

No one expects a rider to learn the skills to ride efficiently @ 100 rpm in a short space of time. The thing is that if they never go above 85 rpm then they're hardly going to get good @ 100 rpm. And that is the sort of cadence that the best riders produce at peak power.

 

[jimboalee]

The majority of members on this forum are either commute or leisure cyclists.

The 'efficiency' they would be more interested in might be kCals/mile, i.e. the amount of food they need to eat to get to the end of the ride.
In this scenario, all they need to know is what feels good and how much energy the cold wind is draining from their body.

If 'what feels good' is 90 rpm along the flat, it's no good having a bike with a single speed 76" gear. This would mean the rider would not 'feel good' until he is riding at 20 mph. On a 24lb bike, that might be 200Watts, which IMHO, is too high for sustained riding on 100 km Audax and longer.

On the gym bike while proceeding through my 'looksie' routine, he might find 90 rpm 'feels good' at the 150 Watts breakpoint.
On the same 24lb bike, 150 Watts will get it along at about 17 mph. 17 mph is a 64" gear at 90ish rpm.

Now the rider needs a bike which has to have a 64" gear so he can ride along happily at 90 rpm giving 150 consistant Watts.

Now for ME, and me only, the 76" gear would be perfect, because I ride at 76 – 78 rpm nearly everywhere. It’s the way I'm built and it aint gonna change for a long , long time, if ever.

 

[jimboalee]

Let's have a look at some bikes aimed at 'beginner' cyclists.

The Rover Safety bicycle. 26" rear wheel, 40T crankset, 20T sprocket.
Aimed at everyone, this bike had a gear of 52", which gave 11.5 mph at 75 rpm. This would require 90 Watts.
The purpose of cycling in 1885 was to have a 'nice day out', not get hot and sweaty, but amble along chatting to your fellow cyclists and having a thoroughly enjoyable time.
IF IT WASN'T, CYCLING WOULD NOT HAVE BECOME SO POPULAR.

The Raleigh Burner 16. 16" rear wheel, 40T crankset, 16T sprocket Single speed.
Aimed at five and six year olds, this bike has a gear of 40", which gives between 10.5 and 11 mph at 70 rpm. The youngster needs to pedal at 80 Watts.
My son had something similar when he was six. 11 mph was his upper limit and he never complained of pedalling too slowly.

The Raleigh Chopper. 20" rear wheel, 46T crankset, 18T sprocket through a Sturmey AW3.
Aimed at 10, 11 or 12 year olds, this bike had a top gear of 69", which gave 15 mph at 75 rpm. The rider would need 130W to get to that speed.
Many of my school chums had these and never complained, except that they weren't geared high enough because to get some real speed, their legs were flying round, which was uncomfortable.

The Raleigh Shopper, or BSA 20. 20" rear wheel, 46T Crankset, 15T sprocket through a Sturmey AW3.
Aimed at young ladies and housewives, this bike had a top gear of 84", which gave 15 mph at 60 rpm. Approximately the same power as the Chopper, maybe 135W due to the larger rider.
My cousin Angela had one for her 13th Birthday. It was passed to my mum and I revised the gearing when my mum was 72. I changed the sprocket to 18T to give a 68" high gear, meaning 12.5 mph ( 100W ) at 60 rpm.

Specialized SWorks. 700C rear wheel, 53/39 chainset, 12 – 27 cassette.
Aimed at the serious race competitor or the DREAMER WITH MORE MONEY THAN HE KNOWS WHAT TO DO WITH, highest gear on this bike is 119", and goes in sensible steps right down to 39". Seeing the bike only weighs 15lb, any DREAMER complaining about the gearing on this bike needs shooting because they are quite obviously a spoiled B.

 

[jimboalee]

Jimbo

With respect, and you may just be trying to help, this is beginners. Beginners ask simple questions and appreciate simple answers. Filling a thread with the kind of response above will only confuse, and really isn't necessary.

The guy asked for a guide to bicycle gearing.

That was chapter 2. Chapter 1 explains how to calculate gear lengths, what power is and what cadence is.

I was assuming the OP is already familiar with the topics covered in Chapter 1.