Why did I drop my bike?

[Cuchulain]

This morning on my usual route to work on my Xj6n I'm pulling up to a junction where visability is poor. I'm rolling up to the line, can't see anything so just start to pull away when a cyclist comes suddenly into view on the right. He's carrying some speed as it's down hill so I quickly brake and before you know it I've toppled over.

I know it's not a particularily uncommon thing for newer riders to do but I can't really pinpoint what i did wrong and I was hoping some experienced folk might be able to shed some light on why this happens and how to avoid it.
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CBT 15/6/2011 Theory Test Passed 6/2/2012 Module 1 Passed 11/6/2012
Module 2 Passed!!! 19/6/2012

[SQL]

Brake sharp and lose balance

[Karlbristol]

[Cuchulain]

[Nexus Icon]

Did you forget to put a foot down when you came to a stop?
It sounds daft but my now wife did that on her cbt a few years ago. I laughed. A lot. I felt a bit mean but I couldn't help it.
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Greetings from Shitsville!

[MC]

Recently had my first low speed drop (in over a years riding). I think the weight going to one side quickly can easily catch you out, and in a panic situation your not ready for it.
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Yamaha MT-03 '08 (crashed)
Honda XR-125L '04

[barrkel]

There's nothing wrong with using the front fairly sharply at low speed - as long as you're dead straight. Something you'll learn is to make sure you're straight before doing significant braking. I seldom use the rear on my VFR unless it's wet and I want to eliminate transmission slop when turning into junctions on slippy roads.

What happens when you're leaned over is that you're steering a little bit into the turn, and that's part of what's keeping you upright. The front wheel has, via forward motion, a torque effect on the roll angle of the bike - this is why countersteering works.

When you brake, you're trying to stop the front wheel turning. But the road wants it to keep on moving. This has the effect of pushing back in exactly the same direction that the steering is pointed in. If you're dead straight, then everything is fine, all the force is trying to slow you down (and potentially put you into a stoppie).

But if your steering is at an angle (like in a turn), this force has a sideways component applied at the bottom of the bike. It's like pulling a rug out from underneath you.

The solution is to steer deeper into the turn (so you countersteer upright) and then apply the brakes with straight steering. But this is something you'll learn instinctively over time.

There's also a planning aspect. When you're on a bike with a high centre of gravity, you can't afford to make as many speculative moves that get aborted upon better observation. You need to make observations sooner, before you decide to move.

The situation is different on a scooter, which has a very low centre of gravity - they're much easier to hold up if braking while turning, which is part of the reason they're better for cities, where timely, total observation is not always possible when making progress.
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Bikes: S1000R, SH350; Exes: Vity 125, PS125, YBR125, ER6f, VFR800, Brutale 920, CB600F, SH300x4
Best road ever ridden: www.youtube.com/watch?v=s2MhNxUEYtQ

[Rogerborg]

Root problem was giving way to a pedalist.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Ribenapigeon]

[trevor saxe-coburg-gotha]

[BakesBeans]

At those junctions where there is a blind spot, or difficult to see, it's best to always come to a complete stop anyway.
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Current: Kawasaki ZX636
Previous Bike: Honda CBR600F ABS, Yamaha XJ6 F Diversion ABS, Honda VFR400 NC30