Trying to decipher the natural gauge for riding motorcycles (i.e., when exactly to change/shift gears) into words for human interpretation is a highly challenging task.
I say this to excuse any lack of explanation around answers or specific numbers for intricacies that you sought to answer when researching this topic.
Or maybe I should just stick to riding motorcycles instead of writing about them too…
All jokes aside, for the purpose of this post I would like you to appreciate numbers as “just estimates” and instead use the sound and feel of your motorcycle as a more accurate gauge for when to change/shift gears.
The average RPM for the perfect gear change sits between 4000 to 7000 RPM on most motorcycles. However, if you are racing or riding track then a higher RPM is required to carry a higher number of revs (to sustain maximum speed) through gear changes.
Ok, So How Exactly do “RPMs” work? i.e. What Purpose Does It Serve?
RPM (revolutions per minute) is a metric used to measure the number of revolutions the crankshaft (of an engine) has made within 60 seconds. This means the faster your engine turns (or rotates), the higher the RPM (i.e., the number of revolutions in a given minute) will be.
The majority of motorcycles will display this information on a gauge called a ‘tachometer’ (link to Wiki). Revs are displayed in a 1 to 15 numerical format (and may vary depending on the bike or manufacturer) which in fact is a measure of every “1000x revs per 1 minute”. This means when a 1 is displayed, the crankshaft (of the engine) is in fact making 1000 revolutions per 1 minute.
Displaying this information is particularly useful to riders (and engineers) to help with the timing of when to change gears or to gauge the number of revs being applied through the engine.
When is the Perfect Time to Change gears While Riding a Motorcycle?
Perfect gear changes are determined by the rider’s understanding of how an engine sounds and feels. In the motoring industry, this is called “the art of understanding power curves”. The word “power curve” is used to essentially describe the sounds that an engine makes through the gradual build-up of revs, through until its peak, and also when revs are dropping back off (i.e., plateauing).
I’m going to assume that if you’re reading this post you’re a beginner, so a ballpark figure for the perfect gear change (in every gear i.e., 1st to 6th) would specifically be at 5000 RPM (for most bikes). So, it’s a good idea to familiarise yourself with how your engine sounds and feels at this rev mark.
|Purpose (i.e. Riding Style)||RPM Range (Revolutions per minute)|
|Fuel efficiency or economic riding||4000 RPM – 7000 RPM|
|Performance and riding with full advantage||8000+ RPM|
The image below depicts a typical example of what a power curve looks like, which should also help to understand how an engine may sound when revving around the 4000 to 7000 RPM mark.
As you can see, the image above is reflecting the engine’s RPM at around 4000 to 7000 where the power has built up enough RPMs for gear change but is yet to reach its full capacity.
In normal riding circumstances, this is the perfect time to change gears.
Changing Gears When Racing Or Riding Track
The next image is an example of when a rider would change gears in a racing environment. Here you can see we are aiming for a higher RPM range (within the engine’s power curve cycle) as we are trying to maintain higher revs for maximum speed capacity through gear changes.
Side Note: Higher Revs are used for gear changes when racing (or riding track) to compensate for the lack of acceleration (i.e., torque) within newly selected gears (as every new gear in the upshift will have a lower torque resulting in less acceleration).
So, to carry more power (and maintain higher speeds) through the gear change, we keep the revs higher.
For example, 1st gear will have the highest amount of torque (and the highest amount of acceleration) but is also the shortest gear within 1 to 6 (i.e., meaning, to go from stationary to peak RPM in this gear comparatively will take the least amount of time) resulting in lower top speeds.
On the opposite, 5th or 6th gear for example will have the highest top speeds but the least amount of torque (i.e., acceleration).
Understanding this allows us to use downshifts to our advantage (for hill climbing and increasing speed) when in the lower RPM range of higher gears. All you do is “drop into a lower gear” which in turn will give you a higher acceleration (and engine braking for taking corners and climbing uphill).
Naturally, the more you ride, the more you’ll build up a mental gauge for how your bike sounds and feels in the mid to high RPM range.
This will help with casual street riding, giving the bike longevity, cornering, wheelies (i.e., stunts) and ensuring the best performance is delivered, no matter the environment.
Why? Because all bikes are different even when they’re the same? Huh? What?…
Ok, so imagine you have two bikes of the same make and model with exactly the same specs on the dyno (find out what a dyno test is here), it’s still almost impossible that each bike will deliver the exact same performance when riding (this is because of the minute differences in every single bike, i.e., tyres, weight, responsiveness etc).
That’s where the rider comes in! The person controlling (i.e., riding) is the biggest determining factor of differences in performance from the engine (yup! it’s probably a good time to lay off the burgers!).
In fact, it’s the very reason why formula 1 is so interesting. As teams are allowed to spec their vehicles to racing criteria, but, ultimately, it’s the driver who will interpret and then deliver the best performance out of the engine (which brings us back to the topic of having a mental gauge).
Why do some riders redline the RPMs When Changing gears? And How BAD is This style of Riding For The Engine?
Red lines are displayed at the end of a rev range (on a motorcycle’s tachometer) to represent the maximum number of RPMs that can be safely applied through an engine before causing damage (i.e., the engine’s limit).
Naturally, an engine will sound a lot louder in this zone which translates as the perfect time to change gears. Such information is particularly useful for professional racing, as riders will learn and gauge the peaks and troughs of power curves, in order to make better decisions for performance.
So, does red lining cause Engine damage?
Regularly redlining a motorbike will reduce the engine’s (and other components) longevity (as technically you’re “thrashing the engine” or at the very least “pushing it to its limit”). So, unless you’re a professional racer (which I’m assuming you’re not) then it’s best to change gears at the lowest possible RPM to give your bike the best chance of lasting a long time.
Will over-revving (i.e. riding in one gear) Cause damage To The Engine?
Over-revving will likely damage the engine’s valvetrain (link to Wiki) resulting in broken springs, pistons, and valves. A good safe running engine will rely on “perfect timing”, so when the valve and cams (link to Wiki) are mistimed then the damage is inevitably inescapable.
Why does an engines Power Drop Off (or max out) When Red Lining?
Three words, “engine load capacity”. I.e., the limit of each gear (mechanically) and engine RPMs that can safely be managed before failure.
The engine’s limit is programmed and controlled by the ECU (engine control unit), sometimes referred to as the ECM (engine control module) which is designed to reduce or cut off the fuel supply when over-revving of the engine occurs (technically acting as the brain of the engine). As a result, there is a plateau in speed from the reduced (or a set limit of) power being distributed by the engine.
Does Under-Revving (i.e. changing gears with a low RPM) Cause Damage To An Engine?
Under-revving may well result in ‘engine stalling’, which is essentially the process of an engine shutting down (or switching off) to protect itself from further damage (caused by insufficiencies and imbalances of fuel, air or mechanical momentum).
Frequently stalling an engine can cause damage to gears (within the gearbox transmission) and wear and tear to other engine components (such as the battery, starter motor, sprockets and chain).
Prior to stalling, the engine may begin ‘lugging'(frequently described as juddering) as a result of being overworked (i.e. riding in 5th gear at 15mph). Each newly selected gear within the gearbox sequence will require additional momentum to operate (compared to the energy needed for lower gears due to its larger diameter and weight) consequential of providing the higher energy output needed for higher top speeds.
But with a lack of supply and additional requirements, there is conflict, resulting in a deficiency of the energy needed, so the ECU will shut down the engine.
How Do You Get A ‘Smooth Gear Change’ Every Time?
The simplified steps for smooth gear changes involve:
- Rolling off the throttle
- Squeezing in the clutch
- Shifting the gear selector
- Then slowly releasing back off the clutch while you’re pulling back the throttle
Simple, but not easy for beginners! I say this because a perfectly smooth gear change involves a little more than the above.
So as we already know, changing gears at the correct RPM is crucial, right? Correct! But did you know that the timing and speed (of the gear change and travel) are equally as important too?
Choosing the appropriate gear For the Speed At Which You are Travelling
Taking a corner in 5th gear is likely not the smartest idea, but neither would be overtaking another vehicle in 1st. The speed at which you’re travelling should determine the appropriate gear to select. For example, if you were riding at 50mph in 4th gear then dropping gear would be a harsh transition resulting in sky-high RPMs.
Why? Because, when a gear is engaged (via the clutch), both the engine and the transmission are turning at the same speed.
But when you pull on the clutch, you are essentially separating the two (i.e. disengaging the engine from the transmission) and going into neutral resulting in the engine and transmission spinning at varying speeds (which is only safe and normal when in neutral).
This means for a smooth gear change you must keep the engine and transmission rotating at relatively similar speeds. That way, the clutch can make a smooth transition when re-engaging the newly selected gear (i.e. merging the transmission and engine back-up). But how do you achieve this?
Two words, “rev matching”.
What is “Rev Matching” and how does it relate to A smooth gear change?
Rev matching is the art of a rider keeping the engine RPM spinning at a similar speed to the engine’s transmission (via the throttle) within gear change. But unfortunately, this is a lot “easier said than done”.
There are two main benefits to rev matching which is:
- Decreasing the amount of wear that gear changes have on the components of the engine
- Ensuring a good balance in the operation of the motorcycle components (i.e keeping everything working in harmony)
But to properly understand rev matching you must first understand the operation of a motorcycle’s clutch.
So, the key takeaway from the video is to remember that the ‘clutch basket’ is always rotating with the speed of the engine (via the crankshaft) and the ‘inner hub’ is always rotating at the speed of the gearbox (i.e. the speed of the rear wheel).
A ‘Rev Matching’ Example
For example, if you were riding in fourth gear and wanted to shift down to 2nd you would pull in (i.e. disengage) the clutch and shift down to 2nd.
Great! but now the gearbox is spinning at a much faster rate than the engine. So, to match it up we blip (i.e. quickly throw back) the throttle to bring the speed of the clutch (i.e. engine speed) up to match the speed of the gearbox (i.e. speed of the rear wheel) and wollah! we have a smooth gear change.
Do NOT worry if that doesn’t make sense, as all you need to do is watch this video on how to put this into practice.
Pre-loading the gear selector
Preloading describes a rider maintaining slight pressure on the gear selector right before physically changing gears. Doing so reduces the loss of RPMs within a gear change resulting in a smoother transition.
How do you preload the gear selector?
Preloading the gear selector involves applying slight pressure with your left toe to the selector for a few short seconds before making the change. Once you are ready to change gears, roll off the throttle, pull in the clutch, and then shift the selector while rolling back on the throttle.
Preloading also reduces the need for heavy squeezing on the clutch which is great for making a fast gear change at high speeds.
Good Clutch & Throttle Control
Chances are that you already have this one locked down, but it’s still important to discuss. While the most obvious, improper use of the clutch and throttle will inevitably end up in juddering, stalling and rough gear changing.
Equally, holding in the clutch for too long (of a period) is a surefire way for the engine and gearbox to spin at different speeds, resulting in a bang (rough gear change) when the two join back up (i.e. when the clutch re-engages).
Throttle control is vital to smoothness, as the number of revs you apply to the engine will affect the engine’s RPM. So, for argument’s sake, if the engine was at 5 (x1000) RPM and you wack it back during a gear change, it’s likely the engine will be spinning far too fast to re-engage with eh gearbox (resulting in a harsh gear change).
This brings the question, if you’re doing all the things (i.e. rolling off the throttle and preloading the selector) can you change gears without the clutch?
Using RPMs To Change Gears Without Clutch
Clutches are designed to disengage the gearbox and engine and then re-engage the two via the clutch pack in a smooth controlled manner to provide you with smooth gear change.
I wouldn’t recommend clutchless shifting (unless you’re very experienced) for downshifts. But for upshifts, clutchless shifting will work just fine for the majority of bikes if you can manage a fast gear change (i.e., preloading the selector and proper use of the throttle).
How Clutches Work And Relate To Changing Gears
A motorcycle’s clutch is made up of friction plates that separate and then join back together in gear changes. Within the diagram below, each plate is joined either to the engine’s crankshaft or the input shaft of the gearbox.
When a gear is engaged, the plates are joined, but in neutral, the plates become separated. These plates are designed to engage smoothly while rotating to give the rider a smooth gear change when using the clutch.
The image below will further explain how this works.
But with the friction plates apart (i.e., separated and the clutch engaged) … The gears within the engine’s gearbox (attached to the rear wheel) and crankshaft (i.e., engine) are left to independently merge (which in the event that they were spinning at different speeds could be catastrophic).
This is why matching their speeds are so vital.
As you can see from the numbered sections 1 and 2 in the diagram there are gears (i.e., cogs) that must merge together when a gear (that you select) is engaged (i.e., the top and bottom rows become a single unit or system, they join up and move together).
A smooth entanglement of the gears can only take place with both rows rotating at similar speeds, which is why an upshift is usually safe to make without engaging the clutch.
Why? Because naturally when you disengage the clutch, the engine speed will begin slowing down, but equally, every newly selected gear will begin rotating at a lower speed.
So, with the right speed (of travel) and timing (of gear change), the rider can make an upshift (and match the two speeds) without using the clutch…Just don’t expect it to always be smooth!
Is there a Way Of Using RPM For Skipping Gears Within Gear Changes?
Motorcycles use a ‘sequential gearbox’ (link to How Stuff Works website) which essentially means you must change gears up or down the gearbox in sequential order. 1st, can only lead to 2nd, and 2nd can only lead to 3rd and vice versa.
That being said, through the use of a clutch, you can make several gear changes while riding in neutral before then releasing (back-off) the clutch to reengage the newly selected gear.
So yes, you can skip gear changes, but this only makes sense in specific circumstances (i.e., when dropping down from 4th to 2nd for taking a sharp bend).
Conversely, I’m yet to find a reason why you would skip gears in an upshift, so if you know something I don’t, then leave an answer in a comment (via the comment section) below.
Wow! writing this post wasn’t easy but I certainly learnt a lot from the sheer level of research I had to do. The key takeaways are to always use the clutch for a gear change, change gears at around 4000 to 7000 RPM for regular riding, and preload the gear selector a few seconds before making a gear change.
And don’t forget! The sound and feel of your bike are the most accurate gauge for when to change gears (I explained how to understand this in the ‘power curves section’ of this post).
That’s really it! If you enjoyed reading this post, then leave a comment below, and make sure to check out the rest of our content about motorbikes too.