An alternative, or more accurately a supplemental way to scrub speed is engine braking.
How engine braking works.
When the throttle is open, air and fuel are readily pulled into the cylinder by the piston as it descends during the intake stroke. When you close the throttle the piston is still trying to draw air in, but the throttle plate is closed, so the piston is essentially sucking against a closed tube. The vacuum that’s created puts drag on the piston which slows it down, and that in turn slows down the rear wheel.
The higher the engine rpm when you close the throttle, the higher the suction and the greater the engine-braking effect, so you can increase engine braking by downshifting a gear or two.
Is engine braking bad for your engine?
The short answer is no, not in the slightest. But I can see where the concern comes from. Engine braking causes the engine to rev up and sound strained, but unless you’ve downshifted to such a low gear that the bike is spinning up into the redline, no harm is being done.
However, there are issues that so-called 'experts' and even Wikipedia like to talk about, so let’s apply some common sense and explain why the two most common concerns aren't legitimate.
Lack of lubrication?
First up, some claim engine braking can cause damage due to a lack of lubrication. Well, the throttle controls the throttle valve, not the oil pump, so it’s still doing its thing and actively distributing oil to the transmission, piston, cams, and all the other parts, so there’s plenty of oil going around while engine braking.
If you’re on a two-stroke, where the lubricating oil is mixed in with the gas, I can see how lack of lubrication would be a concern. But fuel is still being fed via the pilot circuit, plus there’s ample residual oil in the top end to deal with a few moments of engine braking. The only scenario that might actually be a problem would be engine braking to maintain your speed on a miles-long descent, like coming down a mountain.
Transmission and clutch wear?
OK, how about transmission or clutch damage? One of those must suffer while engine braking? No, and why would they? Both the cogs in the trans and the clutch assembly are designed to handle all of the engine’s power, and if they can endure full-throttle acceleration from a stop, they can certainly handle a fraction of that force while engine braking. So don’t worry about it. Neither the transmission gears nor the clutch plates care which direction the force is coming from. (Unless it’s a slipper clutch, which will only care when back torque, i.e. engine braking, is especially intense.)
All that being said, downshifting when the bike is already revving super high and forcing it to spin into the redline is understandably a bad idea. Don’t do that. If you do, it might actually break your engine.
And, of course, you don't want to upset your chassis, so any time you’re downshifting it’s important to rev match so your shifts are smooth and controlled.
There are actually several benefits
Okay, so engine braking is not imparting any undue strain or harm on anything. In fact, it’s actually beneficial in some ways.
Engine braking actually has some benefits, such as preventing your brakes from overheating.
For starters, using intake vacuum to slow down instead of the brakes means your brake pads and discs get a rest. It’s a small benefit, but a benefit nonetheless. And probably the most valuable use for engine braking is at the end of long straights, when downshifting and engine braking can keep your brakes from overheating. Engine braking is also an important part of slowing down for a corner because it ensures you’re in the meat of the engine’s rev range after the apex.
So, if you’ve been wondering if engine braking is bad for your bike, or perhaps you didn’t even know what engine braking is, now you know, and now you know that it’s viable, it’s safe, and it’s a valuable skill to have as a means of controlling your motorcycle.