Riding the rear brake for better balance?

[maxp]

Hi guys, first post so hello!

I did my CBT a couple of weeks ago and have been thinking a few bits over.

One of the instructors mentioned that 'riding the rear brake' would increase balance during low speed maneuvers.

Can anyone explain if / how this works? The more science the better!

[Islander]

It's primarily a balance between clutch and throttle so that you're feeding power to the rear wheel which loads the suspension, using the back brake then enables you to adjust the speed while keeping the drive train under tension - keeping the suspension loaded and hence, the machine more stable.

[MCW]

Helloooo! And welcome.

Better (wo)men than me will be along in a minute to explain it all but, in my experience on a 125, clutch and back brake for slow control is more important on bigger bikes. I can crawl along in 1st gear just using the throttle. That doesn't necessarily mean that this is a good thing to do...

[Polarbear]

Ride how things suit you!

I use the back brake about once in a millenium, haven't crashed for 33 years which means jack shit. (or back brakes are redundant )

Ride how you ride, as long as it's good.
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Triumph Trophy Launch Edition

[skylineonfire]

[cimbian]

I found that riding the back brake during slow control made my riding more jerky. I put this down the the brake overcoming the clutch-slip making the effects of clutch slip adjustment very grabby.

Once I learned to cover the back brake and only dab it lightly when needed everything became so much smoother.

All in my VERY humble opinion, of course.
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22PlusY
Current: Moto Guzzi 1100 Breva. Previous: Honda XL650V TransAlp
Bearded, Balding, Born again Buddhist Biker

[Teflon-Mike]

As made by an internal combustion engine, Power = Torque x Revs'

Engines make more power as the engine revs increase, usually, though not in a direct linear proportion, as the torque tends to increase from low revs and then drop off towards higher ones, giving the hill-shaped 'power-curve'.

OK.... next you have a gearbox Gearbox will usually REDUCE crank-shaft rpm through shafts and cogs to turn the back wheel at a much lower speed.

Power STILL = Torque x Revs, so 1st gear gives a reduction of may be 30x engine speed, but multiplies engine force 30x...

So, at tick-over engine is turning maybe 1000rpm, and engage first wheel, it will try and drive the wheel, at 1000/30= 33revs per minute.

Back wheel is probably about 600mm in diameter, with a tyre on it, giving a rolling circumference as near as makes no odds of 2m, or 2m per rev.

That means, 67m per minute, or near as makes no odds 4Km per hour, just under 3mph. Ie a little less than walking pace.

At LEAST on a lightweight 125.

Little 125 has a small, low powered engine, rated at maybe 10bhp, at maybe 10,000rpm, lower down the rev-range it obviousely makes a heck of a lot less power, and at tick-over, its almost bugger all!

So, to make the most of that power...... torque x revs remember.... they have a LOT more gear-box reduction to multiply the small force they make and help get the bike to shift.

So, that 30:1 reduction is not far off what many little bikes offer, and with that amount of reduction, they CAN be trickled along clutch out at something a lot LESS than a comfortable walking pace.

However, with so much reduction.... rev-em-up... and they might go through that 10,000 rpm power peak, BUT... for easy numbers... lets just take it there, and stick an extra 0 on the end of everything...... 1000 revs = 4Km/h... so 10,000 rpm takes us to 40Km/k.... about 25mph, at which point we have to hook another gear.

That gear will also be fairly low, but may take us to 40mph, third then perhaps to 60mph, and forth? well, theoretically probably be good for about 70, which the bike might or might NOT have the power to actually achieve..... and fifth, if there is one? Well wont do much to help the bike go faster, because 10bhp probably wont shift the wind resistance much over 70mph, but MIGHT let you knock the revs back to cruise more comfortably at maybe 55.

So, little bikes have pretty low gears, to get the most out of thier small power allowance, AND will usually go less than walking pace completely clutch out.

Right, step up to a 500 DAS bike.... this now has 50bhp instead of 10. Probably still got a similar shape power curve and rev range from a 1000 rpm tick-over, to a 10,000rpm peak power..... BUT delivering 5x the power at peak from almost 5x the engine displacement, its probably producing almost five times the power at every other engine speed too.....

So, where your 125 at tick-over was probably only making 1 bhp, the 500 is making 5.... probably as much as the 125 did at about 6000rpm in its 'sweet-spot'.

We could gear the 500 the same as the 125, and five gears, giving the same reduction would take us, in first from 2.5 mph to 25mph; second to 40mph, third to 60mph, and forth? well, this time more than enough power to take the bike to 70, and 5th, again, no longer an 'over-drive' to knock revs back at cruising speeds, but bike would still have the stomp to pull it..... but using 125 sized cogs, bike would probably reach the 10,000rpm power peak, at about 90mph, with enough power to carry on accelerating to around 110, if it had another gear or two.

Would be very tiring to ride, becouse the bike would be pulling like fury with that kind of reduction, but 5x the force, and you'd have to keep swapping gears the whole time, and not really gaining much speed for it.

So, knowing that we have five times the torque available almost at any revs... we can use five times LESS reduction, and still get the same force at the wheel.....

Heavier bike though, so we probably don't go that tall on gearing, BUT first gear will be raised, and only give maybe half the reduction, so STILL giving a hefty chunk more force at the back wheel, BUT trying to turn it twice the speed.

NOW your 500, at tick over has a first gear that will NOT let the bike go slower than 5mph clutch out... just over a brisk walking pace, but WILL pull to 50mph.....

Great for mormal riding, but slow speed work? HOW do you hold the bike back and make it go slower?

Some-how you HAVE to 'defeat' the engine and gear-box. Engine doesn't WANT to turn much slower than tick-over, and with the gearing fixed by cogs, back wheel will turn at whatever speed the gearing allows.

Only way to make the engine go slower than tick-over is to use the brakes and make it labour, and that risks it stalling.

Only way to make the back wheel turn slower than the engine will drive it through the gear-box, is to pull the clutch in and 'waste' engine revs through slip.

THIS is why it is tought.

To balence clutch, rear brake and throttle, 'busy-engine' clutch slip and back brake.

To defeat the gear-box and MAKE the bike go slower than it is designed to go.

It is DSA 'approved practice', and it is what every DAS instructor gets people doing, becouse its now engrained as the 'only' way to make a big bike go slow.

And it is 'sold' as 'good control'.

It is NOT... I'm old school and a trials rider. Trials riders are the MASTERS of slow speed control, this is what the sport is all about, and we DO NOT ride on the fucking clutch and back brake the whole time!

Its a cheap 'trick' to defeat design. In trials... we redesign, and use ultra low gearing to go ultra slow. My 30 year old Comp-Trials is a 250... makes about as much power as a CG125... but from pretty much tick-over! Has LOADS of 'torque' and that is multiplied by a gear-box that provides about 6mph FLAT OUT in first gear, and maybe 8 in 2nd!

But we are going that slow ALL the time.... on a road bike, you will only want to do it 'occassionally'..... like on Mod 1, going round cones.... or if you ever want to do a U-Turn.

How slow is slow? On a tiddler, gears allow a speed something less than a slow walk, clutch out in first, on a 500, something about that of a brisk walking pace.

You OUGHT still to be able to do the Mod 1 manouvers CLUTCH OUT... you'll just be doing them a LITTLE bit quicker.

BUT, you will ACTUALLY have MORE control.

Stamp on the back brake at slow speed, bikes stall.

Haul in the clutch, remove drive, and they loose stability and WANT to fall over.

I DO NOT teach bussy & breaking as a first resort. I used to like to get students 'up to speed' by getting them up to speed, and riding it 'clean' clutch out, and learning to trust the bike, and lettin the bike do what it naturally does, NOT trying to defeat its mechanics and giving them THREE things to do badly, rather than getting to grips with doing ONE thing 'well'.

90% of riding a motorcycle is ON THE THROTTLE.

Master that, keeping your hands OFF the fucking clutch.... you are learning to ride.

Get the test manouvers mastererd.. I dont CARE if you are doing them a bit quick, and I'm having to trot to keep up with you rather than casually wonder up and down the row of cones......

You have GOT the basics and got the REAL control of the bike......

BUT can take a long time to get that finesse on the throttle..... and particularly if you are on DAS, never done it on a tiddler, and are in a RUSH trying to cram everything you need to get a licence learned in a hurry, rather than being tought to ride.....

Instructors, WILL jump straight in, waving the DSA approved methodology of 'slow riding' as absolute law, and try getting you to do the motorbike equivilent of patting your head while rubbing your tummy while hopping on one leg!

It IS a legitimate technique.... BUT it is NOT 'good' control. Its a cheap trick, in the margins, outside the bikes normal operating perameters, and is actually deliberately de-stabilising the bike, demanding much more control input and effecting 'less' precise control over the machine, to do something, REALLY you rarely ever NEED to!

If you are on a 125 - DO NOT heed it. Do it ALL 'clean' you have NO need to bussy and brake. Do it ON THE THROTTLE and learn that fundemental basic controll finesse that is 90% of ALL riding.

If you are on a DAS bike.... well... dont argue with your instructor... it probably wont get you very far, but if you ARE struggling, ask him if you can TRY and get it sussed 'clean' clutch out first, before trying to jiggle three controls instead of one JUST to go 1mph slower.... and then bring it down ONCE you have the balance; first getting teh feel of doing it at the same speed 'Busy & Slip' using extra revs and JUST slipping the clutch, THEN once you have got it 'busy' bringing speed down using busy & brake.......

As said, its a legitimate technique; its even an approved technique... BUT..... its NASTY! and its NOT a demonstration of superlative 'control'...... though they DO like you to use it, because while it shows not one bit whether you can apply delicate throttle input, as required by 90% of your every day riding.... if you can pat your head, rub your belly and hop on one foot? Well? It shows some control 'dexterity'!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Islander]

Aaaaaaaaanddddd breathe...

[barrkel]

That's a fine book you're writing, Tef; I hope for your wrists' sake you're not repeating yourself, and you are copying and pasting from some larger store of text...

[janner_10]

I think balance is the wrong word.

I use my back brake during slow moving traffic for instance as the braking effect is much easier to smoothly control that using the front.

Can't say about things like the U turn or slalom, as oddly enough not done one since my Mod 1.

But front brake on those two would be daft to use.
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Yamaha FZS600 (Now gone to heaven) > CBR600F4i (SOLD) > '99 YZF-R1

[Matt-]

It's purely down to what suits you, if you feel more comfy covering the back brake do it theirs nothing wrong with it

Matty
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RIP jack (wheelie king), you will never be forgotten.
Current Bike's - Road Legal TZR 125 Pitbike, Aprilia SR50R 2010

[Rogerborg]

[baggylastard]

[TaiChi]

I'm being uber cynical here, but did Tef create a sock posting just so he could astonish us with yet another one of his essay's of biblical proportions?

[Ribenapigeon]

Now the science and mechanical engineering is done with (really Tef you should write a book, I would buy it, seriously!), try this.......

........Take your bike to a carpark and do a circle say 10m in diameter, not too tight to be challanging but slow enough you need to slip the clutch and ride the back brake. Experiment with brake pressure, throttle level and clutch bite. After a while you will really "feel" what's going on mechanically and how you can control stability with either adding power or adding braking force. Once you "get it" its like a rvelation. Look up slow control vids on youtube as well. I saw an american one where thee back brake thing is demonstrated using. A bycicle which wierdly seemed to ilustarte the principle better for me than the vids using a bike.

Mind though that you can toodle along at 6mph without slipping the clutch at all, just about twice the pace of a brisk walk. Its a good speed for filtering and you can do a figure of eight and slalom at that speed with a little practice. So saving your clutch. brake pads are cheap though.

[Teflon-Mike]

[Teflon-Mike]