Question: Wikipedia says that the bike is the most efficient means of self-propulsion yet invented.
So, when I ride up Delbrook, why does it feel so hard?
Answer: First, Delbrook is inhumanly steep. Buy an eBike.
Second, you might look at your gears. Whoever invented gears should have patented the idea more than 3,000 years ago. Whenever they were invented and by whom, one thing is for sure, they made life a lot easier. Gears on a bike are no exception. Just try riding a single speed up Delbrook.
Your bike gears work together to distribute the energy input required to make it easier or harder to ride a particular distance. Basically they act as energy multipliers.
Most modern bikes with derailleurs have between 21 and 30 'gears.' What bike manufacturers mean by this is 21 and 30 different combinations of ring sizes between your front and rear gear rings. Usually you see a set of three front gear rings and anywhere from seven to 10 rear rings (the rear cassette). In the bike world, we measure each ring in terms of their number of teeth. When you read a bike specification and see that the front cog set runs from 22T-34T-44T, that means the smallest ring has 22 teeth, the next size up 34 teeth and the largest has 44.
On the rear cassette you will see numbers like 13T to 34T. This indicates the cassette has rings with teeth numbers in between these two outer limits.
That seems simple enough. The interesting part comes when you connect gears in different combinations via the chain to produce varying gear ratios. By dividing each of
the back gears into all of the front gears, you end up with a table of gear ratios. A high ratio would be made by combining your largest front gear with your smallest rear gear. In the chart below you can see that's true with a ratio of 4.00 made up of the largest ring on the front 44T and the smallest ring on the back 11T. At the opposite end, if you combine the smallest front ring with the largest rear ring, you get a ratio of .65. The closest to neutral combination comes from combining 22/20 for a 1.10 ratio.
What does this really mean? Basically, the higher the ratio, the more revolutions the back gear makes for each revolution of your pedals, the further the bike must move and therefore the harder it is to pedal. The lower the ratio, the bike moves less distance with each revolution of the pedals and the easier it is to pedal.
Why you care is because you live on the North Shore and you need the lower gear ratios to climb our hills. We have all seen people riding uphill with their pedals spinning quickly and the bike moving slowly - they are using the easy, 'granny' gear ratio. Weirdly, a lot of city bikes don't come with low gear ratios. That's probably because the manufacturer is specifying gears for a less steep environment - like southern California or Florida.
Mountain bikes do come with low ratios suitable for, well mountain biking. This doesn't mean you should buy a mountain bike for commuting around the North Shore. You should get the bike shop to install the gears that can get you uphill on your favourite city bike. They'll swap out rings and cassettes for you, no problem. We never care about the top end since we almost never use the largest front ring riding here. But, we really care about the low ratios. If the gear ratio table does not give you a low end ratio (close to one or below one) ask them to change it up. Or move to Florida or Richmond.
You can just eyeball this too. How we tell is by looking at the smallest front ring and then looking at the largest rear ring. If it looks like the largest ring in the rear is bigger than the smallest ring on the front, you have a good climber. If you have a huge big ring on the front, you will likely never use it. For the North Shore, we like 22T 32T 42T (or 40) on the front, and 11T-34T on the back. Essentially those are mountain bike gears, but we put them on our city bikes.
Truthfully, the best gearing depends on many factors, including your weight, strength, how far you'll be riding and what loads you typically carry.
There are several online gear ratio calculators for bikes and some manufacturers publish gear ratios. Don't feel you are stuck if you have a bike that is a chore to ride uphill. Just take a look at the gears and get the bike shop to make adjustments accordingly. See you on Delbrook.
The Pedal Pushers are Dan Campbell, Antje Wahl, Anita Leonhard and Heather Drugge, four North Shore residents who use their bikes for transportation. northshore. pedalpushers@gmail.com
