Author Topic: Gear Shifting  (Read 1298 times)

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Offline Bob Guercio

Gear Shifting
« on: October 21, 2012, 01:26:07 pm »
Hi All,

I just purchased a Schwinn bicycle from the Voyageur 2 serious and I absolutely love it.  I am 67 years old and this is the first time in my life I've owned a decent bicycle.

That said, I don't understand the gearing.  The left handlebar has a switch with three positions and the right has one with seven positions.  All my riding has been with the left switch in the second position and I control the gearing by changing the right position switch through the seven possibilities.

This is all I do because I don't understand the gearing.   Please tell me what the settings should be in order to go from the lowest to the highest through all 21 possibilities.

Thanks in advance,

Bob

Offline John Nelson

Re: Gear Shifting
« Reply #1 on: October 21, 2012, 02:10:28 pm »
The left shifter controls the front gearing and the right shifter controls the rear gearing.

The rear has seven cogs that range from 14 to 34 teeth, specifically 14, 16, 18, 20, 22, 24 and 34. Note that these cogs are all evenly spaced except that there is a big jump between the sixth and seventh cog. The seventh cog provides a very low gear for the steepest hills.

The front has three rings that have 28, 38 and 48 teeth.

The difficult of pedaling is a function of the front teeth divided by the rear teeth. The lowest gear you have (for the biggest hills), in the small front ring and the large rear cog, has a ratio of 0.82. That means that the wheels rotate 82 times for every time you turn the cranks 100 times. The highest gear you have (for downhills) is 3.43, which means that the wheels rotate 343 times for every 100 cranks.

You can continue to do what you're doing if that provides sufficient gearing for you. But if you need further help on steep hills, you can shift that left shifter down to "1" and if you want to go faster on downhills or flats, you can shift that left shifter up to "3".

If you do all the divisions (e.g., in an Excel spreadsheet), you can see that there is some practical overlap in your 21 gear options. For example, if you put the left shifter in "1" and the right shifter in "7", it's the same gear ratio as if you put the left shifter in "3" and the right shifter in "2". Both of these produce two rotations of the wheel for every rotation of the crank.

As you get more experience, you can start to pay attention to the "chain line". The chain runs most efficiently and lasts the longest if your chain is parallel to the bike and not at sharp angles. So that means that you should in general use the "1" left setting with the low numbers on the right shifter, the "2" left setting with the middle numbers on the right shifter, and the "3" left setting with the high numbers on the right shifter. This is just a general guideline and you don't need to be obsessive about it.

To answer your specific question, to go from the lowest gear to the highest gear (not that you'd ever want to), the following are the settings for the left shifter and the right shifter respectively:

1,1
2,1
1,2
1,3
1,4
3,1
1,5
2,2
2,3
1,6
2,4
1,7
3,2 (same as 1,7)
2,5
3,3
2,6
3,4
3,5
2,7
3,6
3,7
« Last Edit: October 21, 2012, 02:19:34 pm by John Nelson »

Offline Bob Guercio

Re: Gear Shifting
« Reply #2 on: October 21, 2012, 07:23:41 pm »
John,

Thank you.

Bob

Offline csykes

Re: Gear Shifting
« Reply #3 on: October 22, 2012, 02:55:37 pm »
I lead development rides for my bike club and can assure you that many people really don't understand the gearing on multispeed bikes. 

You are on the right track by making most of your shifts using the right side.  Think of the left side in terms of terrain: lowest gear (small front ring) for steep climbs; middle ring for easy hills and rolling terrain; and the big ring for flat, downhill, and gently rolling terrain.  Since you don't want to cross-chain small-small and big-big rings, forget that it's 21 gear options.  Keep it simple as you can go crazy trying to remember which gear combo comes next from any one position.

Enjoy your new bike!