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idchafee
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Attention motorcycle riders: a question

Mon Jul 14, 2008 8:43 pm

I know there's several riders on this board and this is a question I think I can get answered here.

I'm taking a riding class. The instructor is really hot on engine braking, downshifting as you brake, etc. I don't get why this is necessary. I drove a stick shift truck for years, and when I wanted to stop I'd hit the clutch and put the gear shift in 1st, but I rarely let the clutch out again until it was time to go again (ie the light turned green). It worked fine, as far as I could tell. Is engine braking on a motorcycle a bigger deal? I asked this in TR's IRC and mattsteg said something to the effect of he couldn't see it (not engine braking) as a viable motorcycle practice. So, my question is: do you riders engine brake? If so, why? Is it safer? Better mileage? Something else?
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Re: Attention motorcycle riders: a question

Mon Jul 14, 2008 8:53 pm

For a car or a motorcycle, it's about control. You want the engine to be engaged because you have maximum control of the vehicle.

For motorcycles specifically, you want to be able to accelerate instantaneously to get out of trouble. You also want some throttle when coming out of a turn, and you don't want to declutch in the middle of a turn while leaned over. The acceleration is what stands the bike up, especially if you need to get out of an emergency situation. The throttle is your friend, but to use it, you can't have the engine disconnected from the wheels.

For motorcycles and cars, you actually are able to drive under more control if you use the throttle intelligently. For example, you can corner faster with better control if you accelerate slightly into a turn. This has to do with "setting" the suspension. In other words, you're putting the suspension under tension, resulting in better response. The opposite would be floating the suspension, which is what happens when you brake in a turn, or at least coast into turn with the clutch pushed in -- the suspension is at full extension, resulting in a lot more movement of the car/bike, and less control.

Note that this probably has a negligible negative effect on motorcycle mileage, and the control benefits far outweigh the mileage losses. In a car, hyper-milers will use the tactic of coasting with the clutch disengaged a lot. This is a valid tactic for getting better mileage. But it should be made clear that you're doing so at the expense of control of your car.
 
SpotTheCat
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Re: Attention motorcycle riders: a question

Mon Jul 14, 2008 9:10 pm

I engine brake in a manual car because you get better gas mileage (if your car shut off fuel in that condition). In the winter, I also did it because my car did not have anti-lock brakes, and it helps prevent your wheels from locking.
 
idchafee
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Re: Attention motorcycle riders: a question

Mon Jul 14, 2008 9:18 pm

Buub wrote:
For motorcycles specifically, you want to be able to accelerate instantaneously to get out of trouble. You also want some throttle when coming out of a turn, and you don't want to declutch in the middle of a turn while leaned over. The acceleration is what stands the bike up, especially if you need to get out of an emergency situation. The throttle is your friend, but to use it, you can't have the engine disconnected from the wheels.


That makes sense for bikes, and of course I did do it in the truck then....otherwise, I'd have just coasted to a stop after the turn and would have looked quite the fool. :lol:

The rest of it....well, that makes sense. But man, at least here at the beginning, if I'm worrying about downshifting, I forget to brake. I can't tell you how many traffic cones I ran over that 1st day while thinking to myself "don't forget to shift down into 1st gear..." and totally forgetting to brake.
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Hance
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Re: Attention motorcycle riders: a question

Mon Jul 14, 2008 10:07 pm

When I used to ride I did it both ways. If I wanted to come out of a corner HOT I would down shift going into the corner to keep the rpm's up. If i was coming up to a stop sign i usually just used the brakes.
 
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Re: Attention motorcycle riders: a question

Mon Jul 14, 2008 10:11 pm

That's why you practice. It needs to be second nature, because operating your bike properly should be. If proper routine operation isn't second nature, you need to practice until it is. Also, coming to a halt and then stomping down 4 or 5 times is kind of a pain in the ass. You've got a sequential shifter. You need to hit every gear anyway, so do it usefully. Also, at least my transmission sometimes doesn't like to shift when halted and I need to roll a bit forward to line things up. If I do end up halted in the wrong gear (like if I had to stand on the brakes on short notice or something) that can be a PITA.

Both downshifting while matching revs on my bike and nice smooth heel-toe downshifts are pretty much second nature when decelerating normally for me. They just make sense. It's safer, more convenient (particularly on a bike), and gives you better control.
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Re: Attention motorcycle riders: a question

Mon Jul 14, 2008 10:20 pm

As others have said (Buub did a good job of it) it's more of a control thing. You need to be able to slow down both ways depending on the situation. and as matt said...the more you do it the easier it becomes second nature.
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Re: Attention motorcycle riders: a question

Tue Jul 15, 2008 12:09 pm

Hance wrote:
When I used to ride I did it both ways. If I wanted to come out of a corner HOT I would down shift going into the corner to keep the rpm's up. If i was coming up to a stop sign i usually just used the brakes.

That's how I ride. If I have to stop completly, I just brake. If I'm slowing to turn or something, I'll downshift.
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Re: Attention motorcycle riders: a question

Thu Jul 17, 2008 1:18 am

Engine braking in any vehicle becomes a critical skill to know when you're driving in the hilly country. Even a small passenger car will eventually overheat the brakes on a long, winding descent if engine braking isn't used. I don't know what the tolerance threshold on a bike is -- higher, I would exepect -- but it won't be immune.

Just don't get into the habit of letting the engine do all the braking without at least touching the actual brakes. As was taught in your driver's ed class, other vehicles operating on the same line of motion as you will detect your brake light much faster than your change in velocity.
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