A very common question on most bicycle touring related mailing lists and newsgroups concerns selecting the proper gearing for a bicycle touring bike.
There are really two answers that are almost instantly heard when the question is asked.
1) You need to select the gearing that works best for you
2) Most stock touring bikes come with gearing that is too high for loaded/self contained touring although that same gearing generally appeals to club riders to whom the majority of these bikes are sold.
I look at it this way. If I am going down a hill and the speed reaches the point where I can no longer pedal then I have a rest and coast down the hill or I turn the pedals slowly to keep blood flowing in my legs.
On the other hand if I am climbing a hill and the resistance is too strong to continue without a lower gear then I have very few options short of a long walk uphill pushing the bike.
I've never heard anyone complain about having too low of a gear available but I've certainly heard people talk about having gears that were too high!
So what can you do if you have a bike with gearing that is too high?
The first thing I did was to find the gear that I liked to use the most on tour as well as the highest gear that I used regularily during that same tour. Of course to be a useful exercise it is important that your route include both ascents and descents and that you carry a normal touring load.
Here are some of the questions that I ask myself following the ride.
- Was my lowest gear low enough to allow me to spin my way uphill without causing a bad burn in my legs?
- Was my highest gear high enough to allow me to cruise down the road at a reasonable speed or was I always wishing for another higher gear?
- Was the spacing between the various gears good or did the test reveal large jumps that were quite irritating?
- Would I be comfortable with this gearing over the course of a hilly eight hour ride?
Once I have this information then I have the basis to decide if I really do need to make changes.
Whenever I am considering gear changes I like to use something called a Gear Calculator. The one I use the most is located at Sheldon Brown's excellent web site. With the gear calculator it is easy to determine how big of a change in gearing that you are considering.
There are many ways to view the gearing information. Although somewhat dated I tend to use Gear Inches as my unit of measurement. Gear inches were originally determined by measuring the circumference of the large wheel on the old pennyfarthings so the number that you see in the calculated result shows the pennyfarthing wheel equivalent for that gear.
When using the calculator I need to enter information about the crank length, tire size, front cranks and the rear cassette. Here are the answers I would have provided for my original Trek 520.
Crank length: 170mm
Tire Size: 700c X 32
Front cranks: 52/42/30
Rear cassette: Shimano (as), nine speed, 11-32
This yields the following results:
(Each column represents the gearing for that particular crank so in this example column one is for the 52 front, column two is 42 and column three is 30).
What this chart tells you is that my highest gear is 127.6 gear inches while my lowest gear is 23.8 gear inches. In practical terms I rarely used even the 93.6 gear inch gear let alone the much higher ones. I also found myself wishing for lower gears on steep hills. The hills were still doable but not as easily as I wanted! Another thing to note is that the difference between gears ranged from 13 to 18 percent meaning that some gears had a much bigger jump then others making it harder to decide to go up a gear or not.
I have made modifications to my gearing since picking up the bike so my answers are different now:
Crank length: 170mm
Tire Size: 700c X 35
Front cranks: 42/32/22
Rear cassette: Cyclotouriste-13, nine speed, 13-34
This yields the following results:
In this example the highest gear is 87.8 gear inches while the lowest is 17.6. I can't recall ever wishing for a higher gear and I've certainly come to appreciate the three lower gears that I have to choose from compared to before. As an added bonous the gears are much closer together too with only a 10 to 15 percent difference between gears. This means that often I discover that my speed has increased slightly and I can easily switch to a higher gear. Over the course of a day this can make a tremendous difference as you fine tune your pedaling and gain that little extra bit of performance and comfort.
When you compare the numbers for these two setups the following things should be visible. The highest gear has dropped significantly along with the lowest gear. The spacing between gears is also much more even so no gears suffer from large jumps. This makes it quite easy to shift up or down a gear to try to obtain the optimal gearing for the terrain that you are going through.
I also use this bike for everyday commuting. In that mode the loads are lower and I can easily push my highest gears. My current gear range is such that I seldom wish for one more higher gear. About the only time is when I am racing a buddy and feel the need for a slightly harder push to drop them behind.
The problem with the setup I've shown here is that I did it the expensive way. I basically accepted the stock bike as is the day of purchase and then gradually upgraded components as time passed and my knowledge level of what I needed increased. This means that I gradually upgraded the rear cassette, front deraileur, front cranks and bottom bracket. I ended up with a very good setup for me but it cost money. If I could go back and do it again I would specify the lower gearing upfront assuming that I planned to do fully loaded/self-contained touring.
Has the quality of my tour improved?
The quality of my touring experience has definately improved. With my extremely low gearing I haven't found a hill yet that I can not eventually climb even with a full load of stuff. Not only can I climb the hills but after doing so my legs still feel energetic.
For me making the gearing changes was definately the right move and one that I wish I had done the day I purchased the bike. Since I already knew at that point that fully loaded/self-contained touring was in my future it would have been the most cost effective way to do it.
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