Question was: how to shift a bike when it takes shifting down 5 gears to feel anything?
Step 1: take some Whiteout (preferred cause it wears off and is very visible) or a marker and mark one tooth on each gear on your bike, front and back gear sets to keep track of where you started counting teeth.
Eg. On a 21 speed bike with 3 front gears you may have 28,38,48 teeth on those gears.
On the cassette or freewheel (back gears) do the same starting with the largest gear and working your way to the smallest. Write the numbers down for each gear eg. 28,24,21…
Then go to:
http://www.sheldonbrown.com/gear-calc.html and enter the information. Don’t worry about the crank length if you don’t know it. We’re only looking for changes in gear inches (select gear inch output). Starting with the smallest front gear going to the largest front gear or chainring, enter the information. With the back gears, enter information starting with the largest back gear going to the smallest gear. Print the chart. What you end up with is a chart that has the lowest gear top left and highest gear on the bottom right of the chart.
What you are looking for.
You want to shift down progressively to a lower gear going up a gradually steepening hill. (On a very steep hill you might be better shifting to a gear low enough to get up a hill and just wait for the bike to slow down while pedalling at a constant speed until your feel resistance (bike has slowed down enough for that gear).)
What usually happens is you waste so much time jumping around from a low gear to higher gear to a lower gear (and you can’t shift fast enough because you have to ease up on pedalling to shift before finding the correct low gear and by then the bike has stopped because derailleur bikes don’t gear down well under load.
With the chart, you want to look at the gear inches. You want to find the smallest jump in gear inches between the largest front chainring and smallest cassette/freewheel gear combination and the next smaller chainring and larger cassette/freewheel combination.
In my case, I’ll shift down using the rear gears (cassette/freewheel). To remember to combination easily, I’ll use a 3 for the largest front (chainring) and a 7 for the smallest rear gear (cassette or freewheel). So top gear on a 21 speed would be memorized as 3,7. Downshifting then to 3,6 and 3,5 etc.
When I look at the chart, I find that the smallest gear inch change to a smaller chainring is from 3,5 to 2,7. In other words 2 representing the middle chainring and 7 representing the smallest freewheel gear (back gears).
I repeat this going from middle chainring to the small chainring and find once again that if I shift down… 2,7…2,6…2,5… that I can shift to the smallest chainring and shift to a smallest back gear combination with the smallest change in gearing. The smallest gear inch drop could be from 2,5 to 1,7. However, going from the innermost front gear to the outermost back gear will cause more wear… its called cross chaining. When hauling a heavy load or going up a steep hill you may find its more important to go to the nearest lower gear and keep pedalling hard to avoid loosing too much speed when shifting. For hills that increase in grade this works best.
If this is not a problem, ie you aren’t going to lose so much speed that you can’t gear down, some people say try to keep the chain as straight as possible. To do this, the large chainring uses the smallest 3 outer gears on the freewheel (5,6,7). The middle chainring used the middle 3 larger gears on the freewheel (3,4,5). The smallest chainring uses the largest 3 gears on the freewheel (3,2,1). This means a larger jump when changing to a smaller front chainring but it makes more sense in that it simplifies shifting while reducing cross chaining wear.
Using this method, I’ll shift 3,7…3,6…3,5…3,4…2,5…2,4…2,3…1,4 and all the way down to 1,1.
This complexity is why most people just don’t get how to shift a bike with chainrings and derailleur gears. You either choose the method of least wear or the method of progressively gearing down when pedalling hard.
When changes in grade are not significant, just drop to the smaller chainring. Think of the front chainrings as high, medium and low gear ranges and the freewheel gears as smaller changes within those ranges.
I print out the chart and tape it to the handlebar. Then I circle 3,5 2,7 and 2,5 to remind me of where the smallest gear changes are when I need to pedal hard.
When it comes to people with 65 gear bikes, 3 chainrings, 7 freewheels, and 3 hub gears… I just basically break down and cry.
Who ever said learning to shift a derailleur and chainring set bicycle was easy?
Be grateful if you only have a single chainring or a geared hub!