Cycling Gear Ratios & Shifting Patterns

Coeus

I have recently adventured into the realm of trying to figure out gear ratios and shifting patterns. I have found lots of calculators online to help with the gear ratios numbers, but trying to decipher what all that means is another issue. So, what does all that gear ratios stuff mean? How does it relate to shifting patterns?

Thanks in advance,
Josh

2LAP

In reality, any numbers assigned to gear ratios don't matter pip. What matters is being in the most effective and efficient gear!

And thats a different story.

Coeus

Since the post, I have found a few places that say that those numbers help you to transition between gears more efficiently. Mostly by double-shifting. Does that make any sense to you?

VeloFlash

Either your legs or lungs will tell you if you are in the right gear!

In the English speaking part of the world, we would refer to a gear as being a .... inch gear. This comes from a prehistoric formula that I believe was derived from the high wheeler penny farthings. It has no meaning other than identifying amongst those who know what it would appear to mean.

It is calculated from the formula number of teeth in the front chainwheel divided by the number of teeth in the rear cog multiplied by 27.

A 53t (front) and 12t (rear) would be referred to as a 119 inch gear.

It is the parlance in the track cycling world as you will hear about (say) the German track pursuit team used a 108 inch gear and 180mm cranks to set their world pursuit record in the 2000 Olympics (track cyclists can only use one fixed gear).

The Europeans use a development formula which is the distance in metres travelled in a particular gear from one revolution of the cranks. Most probably more meaningful to the uninitiated.

Coeus

I see. What about shifting patterns then?

VeloFlash

Can you describe this "shifting pattern" alternatively? I do not understand how the words are meant to apply to bicycle gearing.

On the presumption you mean "when should I shift up or down" you will obtain that through experience. Once you have established your most efficient cadence (this will go up if you are a real tenderfoot) the object of the gears is to keep you cadence within this range throughout the changes in road speed.

You will have three different cadences. Normal flat/ slight undulations/anaerobic short hills, hills/mountains (being slower than normal) and acceleration/sprinting/downhills (being faster than normal).

If this is what you mean then your need to shift up or down will be dictated by your customary cadence range for the particular effort involved.

Coeus

I understand that concept, but here is a link (GeRZ) to what I am trying to figure out. Does this information make sense?

Moose

I think Shift Pattern here refers to the order of chanring/cassette combos you must use to shift through all the gears incrementally based on gear inches, even if this means you have to double-shift to achieve this order.

Interesting for analysis, but not extremely useful in the real world.

__________________
I feel a lot more like I do now than when I first got here.

Coeus

So does that mean that you just shift when you need to keep your cadence steady? How do you know what gears to shift to? Or do you just use a lot of practice?

Moose

I believe that after you've logged enough miles you won't need to think much about when to shift.

I let you know once I've logged enough miles

__________________
I feel a lot more like I do now than when I first got here.

VeloFlash

On your referred web site, Example 3 is the optimum set up.

It must be an older web site as it has only 8 rear cogs when the norm these days (for road bikes) is 9 or 10.

Following the gearing pattern you would go through the gears in your smaller chain ring and go from the small chainring (39t) to the large chainring (53t) and you change your combination from 39/16 to 53/21 then your next change would be to the 39/15.

Unless you are mentally plotting your upchanges or have a gear indicator this appears to be a laborious exercise of double shifting and running the risk of dropping a chain.

If it was a 9 or 10 speed system I would have the 16 rear cog included and this cog would make double shifting unnecessary.

I would not have double shifted anyway unless I was on a long gradient which that gear totally suited. Also there is an efficiency loss in that cogset by going to a 53/21 as you are opening up the chain angle.

In all my years of road racing I have never seen or heard anyone double shift from the small ring to the big ring and back again just to pick up a gearing sequence. You would just live with the gap.

Only experience will tell you when to shift.