Following from my Bicycle Gears for Dummies article, which I might add is for any rider wanting their bicycle gears questions answered!! 😀 Any rider I tell you! Lol 😛 Okay… and just let that moment pass…
Hello Dear Reader! And thanks for joining us as we step back from the gear theory to the practical application of bicycle gears. If you’re familiar with gearing, ratios, high/low etc. then read on. And if not, I’d suggest you take a look at that article first to familiarize yourself with key terms. Plus it’s a damn good article haha 😀 So yes, as I was saying, following the other gears article, I thought it might be useful to take a look at the effects of shifting the gears either way in a number of different practical situations. While I hope to illustrate this in video form soon, I think putting it as clearly as I can in this second article here means that none of the detail will be lost as it might in video form. So I’ve broken the article down to make it easier to find stuff:
- Initial Gear Conditions and Assumptions
- The Triad of Energy, Cadence and Speed
- Gear Shifting for Riding on Level Ground
- Gear Shifting for Climbing
- Gear Shifting for Descending
1. Initial Gear Conditions and Assumptions
- So while I’m assuming a 2-by road bike setup here (with multiple chainrings at the front and a cassette of sprockets at the rear, the same principles apply to flatbar bikes, the difference being the shifters are different – either twist-shift, thumb shifters etc.
- I’m also using mechanical cable-operated gear shifters here. I’d imagine anyone with electronic shifting on their bike might know the basics 🙂
- Likewise, I have a Shimano groupset on the bike pictured in this article. Most shifters have a similar setup and a large lever for shifting to a bigger ring or sprocket and a smaller lever inboard of that, or sometimes a thumb lever on the hood. The Campagnolo Ergopower shifters use an inner lever for changing to a larger sprocket or chainring, and a thumb lever for changing to a smaller sprocket or chainring.
So the systems can be slightly different. But there’s an essence of commonality shared between them. And that is? Well, generally the larger lever or button puts the chain on a larger ring or sprocket and vice versa for the smaller lever or button.
2. The triad of Energy, Cadence and Speed
By way of prefacing the following explanations I want to just touch on this triad because these three things are inherently interlinked.
- Energy refers to the energy you put through the pedals on your bike. Essentially how hard you push, how much effort it’s taking you to turn those pedals. That can be measured in a few different ways:
- Subjectively using the Rate of Perceived Effort RPE scale
- By a measurement of your heart rate. This is directly related to your energy insofar as the harder you’re pushing the pedals, the higher your heart rate will be in order to supply those muscles with oxygen. There is a lag between when you begin pushing and when your heart rate rises. And similarly it takes a moment for your heartrate to fall when you ease off the gas as it were. The duration of that “moment” is a decent marker of your fitness level 🙂 Heart rates are usually measured by wearing a band around the arm or chest which measures either electrical pulses or uses LED light to pick up the pulse that way. Heart rate is measured in Beats Per Minute, or BPM
- By directly measuring the power you’re putting out. This measurement is generally more accurate than the heart rate monitor. It can be more expensive though. A power meter is usually attached directly to your bike. It can be built into the pedals or crank arms, or mounted on the handlebar. Power is measured in Watts.
- Cadence refers to the rate at which you spin the crank arms. One complete revolution from the pedal at, say, the 12 o’clock position, moving through 360 degrees until the 12 noon position again is one revolution. Cadence is measured in revolutions per minute, RPM, similar to any turbine or motor.
- Speed is simply the rate you’re moving at on your bike in Kilometers or Miles Per Hour.
These three measurements are directly and closely related while riding the bike as we’ll see. Believe it or not, I thought this would be the simplest and least facile way to explain what’s going on with shifting gears. But you can be the arbiter of that 😀
3. Gear Shifting for Riding on Level Ground
Using these simple visual gauges, here we’re starting off, everything’s at zero. We don’t necessarily have to push off in the lowest gear, especially if we’re on level ground. It can be more difficult though to push off in a higher gear when stopped on an incline.
So imagine for simplicity’s sake that we’re on a level surface, no incline or descent. We start turning the pedals at a low rate to begin with – our rate of pedalling, or our cadence is low. To turn the pedals even at a low cadence still requires a measure of energy on our part. But flat ground, at a low pedalling rate, expect our energy expenditure is also low. And for that effort, our speed will be correspondingly low, thus…
Since we often push off in a low gear, low enough to get us going, lower too than that with which we’ll reach a comfortable cruising speed, what usually happens is that our rate of pedalling (cadence) picks up. A bit like a motor engine. Our speed will also pick up slightly for a small increase in energy expenditure. But then as our muscles warm up, we start spinning the pedals faster – our cadence continues to increase in other words. It comes to the point where we’re approaching a cadence that is too fast and starts to feels inefficient. It’s time to change gear. We want to shift up to a higher gear here.
So, if we’ve pushed off in a low gear (larger rear sprocket) our first gear change is to the next smaller sprocket. This is called changing UP as explained in my Bicycle Gears for Dummies article. To do this – and don’t worry, if you’re unfamiliar, this all becomes second nature after a ride or two – but to do this, we want to click the smaller lever (or button) on our right hand gear shifter. The right shifter operates the rear gear derailleur. Like this…
What this does is to shift the chain to the next smallest sprocket, in this direction. It doesn’t matter whether you know what’s happened at the rear cassette, but this is what’s gone on when you’ve clicked the shifter as above…
Well done, you’ve shifted up a gear. Just like in a motor engine, after upshifting, the revs drop. In our case, moving to a higher gear makes the bike feel slightly harder to push. But this is negated by the fact that we’re building up speed as we go. Our data will show us that our energy output is higher in order to push the harder gear, our cadence has dropped back a little, but our speed has increased. Like this…
So here we are, cycling along nicely, building up speed gradually just as above, as we feel our cadence increase beyond the level we’re comfortable spinning at, we change up another gear. When we’ve upshifted a couple times, the chain will be in the outer third of the rear cassette. What can happen here is that we might hear a chain rasp noise as the chain rubs against the front derailleur. This is cross-chaining. Here’s an explaination of cross-chaining. We can trim the front derailleur, which means clicking the bigger outer lever on the left hand shifter, but not all the way, a kind of half-click. However, chain rasp from cross-chaining means our next upshift should be at the front.
Of course we can continue upshifting at the rear derailleur as we have been doing, but the rasp gets noisier and the chain becomes more crossed. This is less efficient so it’s better to upshift at the front, using the left hand shifter, thus…
This moves the chain from the smaller inner chainring at the front to the larger outer chainring at the front. Like this…
Often, while it’s not too large of a jump in gear ratio when upshifting sprockets at the rear, when we shift at the front, the jump is quite large and can have a noticeable effect on our cadence. What do you think happens? That’s right, our pedalling rate slows down considerably and we’ll need quite a bit more energy applied to the pedals to get that spin back. What we can do is to upshift at the front to the larger chainring, and if it’s too hard to push, we can downshift one at the rear. Either way, our speed should increase markedly at this point too, thus…
In order to hit our maximum speed, if that’s what our goal is, we can continue to upshift at the rear until we’re in our highest gear. Our highest energy output combined with our highest cadence or rate of spin will have us reach our personal maximum speed on level ground. But what happens if, before we get there, the road begins to inch or climb upwards?
4. Gear Shifting for climbing
We’re in a high gear now, moving quickly. But as we hit the incline, our speed will drop unless we can dig in and find more energy to pump through the pedals. But, assuming we’re near our maximum energy output, we’ll have to consider downshifting. Why? Because otherwise, as the incline continues and we can’t find extra energy, our cadence will drop until we end up stomping on the pedals to get them to turn. We’d end up in this situation, which were it to continue would cause us to almost stall on the hill…
What we need to do before we get to this point is downshift. And how do we do that? Well it’s the reverse of what we did when we upshifted through the gears when riding along on level ground gaining speed.
If the incline is steep and has totally caught us out suddenly then we need a big downshift. In which case we’ll downshift at the front like this…
This will shift the chain from the larger, outer front chainring down onto the smaller, inner front chainring. Because shifting at the front produces a greater change in gear ratio than at the rear, this will make pedalling on the incline proportionately easier.
What we’ll notice now is that our energy output is still quite high, but not just as difficult. Our speed won’t have increased much, both of these factors are because we’re climbing so our energy is acting against gravity as well as generating forward movement. But what will have happened is that our cadence has risen to less of a grind and more of an easy spin. This helps reduce our energy output (our heart rate will decrease), like this…
If the incline continues steadily and we’re at an energy-expenditure level (think heart rate) that we can sustain for the climb, or the incline plateaus for example, then we don’t need to downshift ie. change gear again. If, however, as the incline continues, it either steepens, or we find pedalling becomes a struggle, then we’d benefit from downshifting again. Because we’ve already downshifted to the lower front gear, what we do now is to downshift at the rear. Basically the opposite of what we did when we were riding on level ground and increasing speed. So how do we downshift at the rear? Like this…
While you don’t necessarily need to know in order to just ride your bike up a hill, it’s useful to note that downshifting at the rear means the chain shifts to a LARGER rear sprocket. If you’d like further, I’ve also explained about this in my Bicycle Gears for Dummies article. Once we click this lever it will have this effect on the chain at the rear cassette…
We can repeat this rear downshifting until we feel we can complete the incline comfortably. Or maybe just complete the incline! depending on our fitness or lack of, for that climb. I know I can have bad days, sometimes the wind doesn’t do us any favors etc 🙂 So we may well end up back in our lowest gear to complete the climb. In which case, the chain will indeed be located as in the picture above, on the largest sprocket (the easiest gear).
My advice would be to change earlier on an incline rather than later. Especially on a longer climb, this gives more time to establish a cadence and rhythm that will get you to the top in good style. We don’t want to be obliterated by the time we reach the top. Unless that’s our training goal! Normally we’ll want to be able to continue pedalling over the top and away 🙂
5. Gear Shifting for Descending
So now we’re over the top of the climb, maybe the road starts to descend. We find ourselves in a gear that’s right for climbing, but now we’re over the apex, it’s too “spinny”. Essentially this is the same situation we found ourselves in riding along level ground. Every time we find our revs or cadence go too high, we upshift, just like in a motor vehicle. The only difference here is that that increase in cadence after each upshift happens much quicker on a descent than on level ground. What this means is that we’ll probably upshift through the gears at a faster rate on this descent than on level ground.
But the procedure is exactly the same…
So we upshift at the rear first, then, once the chain is across the outer third of the cassette we might consider upshifting at the front. These are all explained in the Gear Shifting for Riding on Level Ground section above.
While our energy expenditure often drops on a descent if we take it easy, letting gravity do the work for us, we might also fancy pushing downhill. We might want to keep our speed as high as possible. We may want to go for our maximum speed. How do we do this? We simply progress through the gears, finding the gear that enables us to spin at our most efficient rate. While everyone’s different, 90-95rpm is usually cited as the median value. For me, on a descent, I find I can realistically pedal at 130rpm maximum before I start bouncing on the saddle. But that’s just my lack of technique 😛 Many good folk can do much more. We’ll each have our own maximum achievable speed on a given descent on a given day in the given weather conditions. Maximum speed will be found by pushing the highest gear with the maximum energy level we can output. So we’d need to upshift to as high as gear as we can keep spinning the pedals at a rate our muscles can sustain. Hard sprints are usually short so it’s not an endurance effort.
If you are doing that, just ride safe, yeah? Cover your brakes, you’ll likely be on the drops anyway. You are descending on the drops, right? 😀 That’ll help with reducing wind resistance and increasing the speed too.
Hope you find the info you need here or in my other Gears article. I’d love to hear in the comments. Meantime, have fun and take care riding out there, David.