leenoble

Hello, newbie introducing myself with a really inane question.
It's been a while since I rode a bike regularly. I used to have a road racer in my teens which had 5 gears. That was fairly simple to understand in terms of which way to switch gears to go faster or uphill. Now I find myself some ahem! years later having to commute to work by bike. It's got 21 gears which I'm finding difficult to understand.

for example: If I'm in pedal gear (large cog) 2 and I've gone up through the small cogs from 4 to 7, where am I supposed to go next? 3:1? 3:7

What exactly is the order of the gears supposed to be for smooth transitions. I tend to stay in 2 and move from 4 to 7 on my commute depending on the slight inclines. On the way home I can speed along in 3:7 when I get a bit of flat to slight downhill.

Apologies if my terminology is all wrong. I understand the basic concept that large cog to smallest cog will be the fastest but without counting all the teeth and working out the exact values when multiplied I find it hard to see why you would need 21 gears.
Cheers
Lee

Retro Grouch 

Back when men were men and bike frames were steel, we only had 5 cogs on the back. One had to be careful with the selection of front chainrings and rear cogs to make maximum use of every possible combination. That led to some strange shifting sequences. Some guys would type up the various combinations and tape them to their handlebars to help them find the next combination in sequence.

Today, with so many of cogs on the back, that doesn't make as much sense as it used to. Think of your bike as having three gear ranges. Most folks use the middle chainring most of the time and the rear shifter for fine adjustments. Save the granny ring for steep uphills and the big ring for downhills and tailwind days. Your 21 speed bike might only have 10 or 12 ratios that you really use but who cares?

cc_rider

I keep it simple. If I am getting too much pedaling resistance I shift to one gear easier. Not enough resistance I shift one harder. Usually keep it in the big ring, switch to the middle ring when I'm in the middle gears, small ring only for the most difficult climbs.
Generaly don't think too hard about it. Just use what feels right.

Nicodemus

basic rule: chain stays straight. Too steep an angle going from front chainring to rear cog should be avoided.

Hobartlemagne 

When Im accellerating and get to the point where I want to change from the middle chainring to the big chainring, I'll downshift 2 gears at the same time on the back cog. On my bike, that feels like the next gear up from before.
Example: on your bike shift from 2:7 to 3:5

Stacey

Rule of Thumb:

Down hill - big chainwheel, 4-7 in the back.
Flats - middle chainwheel, all gears in back.
Climbing - small chainwheel, gears 1-4 in back

MichaelW

Generally , you stay in the middle ring and use all the rear cogs untill you come to a hill too steep to climb comnfortably (go to small ring) or if you spin out (go to larger ring).
There is a lot of overlap and duplication of gears between the 3 chainrings so you may want to follow Hobartlemagne's advice and alter your rear cog a little when you switch rings to minimise the size of the jump
Try and keep an eye on the chainline and avoid combinations which cross from one side to the other. This will increase your rate of wear.

I try to ride at a constant workrate (ie breathing), pedalling force and pedalling cadence and use the gears to match these factors to the varying terrain. My variable is speed. Racing cyclists often use gears to alter their speed but still have to work harder to go faster.

Bill Kapaun

"Your 21 speed bike might only have 10 or 12 ratios that you really use but who cares?"
Sometimes that can be pretty optimistic, depending on your riding conditions.
I have a 21 speed, but live in a flat area, so I never use the small ring.
(actually I use S-5 when I park it overnight to reduce tension on the RDER spring, because it makes me feel good)
To be honest, I seldom use the middle ring.
I have friction shifters, and it's just too much hassle to shift back & front and hope to find the correct gear.
I typically just stay on the big ring. I'm cross chaining on the lower gears, but I'm willing to suffer!
I'm only in them for a couple "pumps" each. With the friction shifters, I can "trim away" excessve chain rub". If I'm going up a longish slope (rare), I'll drop down to the middle ring.
Go to the link, and you can see just how your gear ranges overlap.
https://sheldonbrown.com/gears/

caloso

This is a great way to think of it. My father-in-law was having the same trouble wrapping his head around the gearing thing. Because he's an engineer, I think he was over-thinking it. But when I explained it as ranges, it became perfectly intuitive for him.

djSlvt

AS IF ASKING A QUESTION WITHOUT DISRESPECTING YOURSELF, AND PUTTING YOURSELF DOWN WILL RESULT IN A VIOLENT FLAMING RESPONSE FROM PEOPLE WHO WANT TO GIVE YOU ADVICE.

It won't.

Try it, so simple.

Nicodemus

Do you jack off to your posts?

Stacey