Triumphrat

Mokupono · 04-07-2007, 11:38 AM

I have a question regarding locking the front wheel when under HEAVY braking - is it normal???

Here is the scenario:

I'm traveling at 35-40mph when I suddenly have to stop so I grab a handful of front brake. Instead of stopping, the front wheel locks and then starts to slide and tuck. This has happened twice -- the first time happened in December. I went down and broke my ankle that time. The second time just happened yesterday but luckily I caught the bike before it had a chance to go down.

My tires are Michelin Pilot Powers with only 1200 miles on them. The first time it happened I thought the tire slid because it was cold but last night I had already been riding 20mi before it happened again. What's going on? I've performed emergency braking on my VFR (Pilot Roads) under the same conditions without ever having the front wheel slide like that.

Thoughts, ideas?

Thanks.

dfib · 04-07-2007, 11:45 AM

Don't lock up the front it hurts!

Are you using your rear brake too?

Mokupono · 04-07-2007, 12:01 PM

Quote:

On 2007-04-07 09:45, dfib wrote:
Don't lock up the front it hurts!

Are you using your rear brake too?

Uhm, these things have a REAR brake???

:-D

Seriously, I rarely use the rear brake for stopping. The last time I actually used it to stop or even slow down was literally 20 years ago and I high-sided. I guess I programmed myself - when in a high speed turn, rear brake = bad things...

Speed3 · 04-07-2007, 12:11 PM

The fastest way to stop is to use the front and rear together. The rear brake works if you hit it hard enough. When panic stopping and you grab a handful of front, learn to modulate it so you bark the tire and then back off a bit. Don't hold it until you tuck the front. your friends will laugh at you. :hammer:

[ This message was edited by: Speed3 on 2007-04-07 10:12 ]

Helmet_Hair · 04-07-2007, 12:38 PM

did you check the condition of your pads? I know you're an experienced rider....but I NEVER use more than 2 fingers on the front brakes of any modern sport bike, it just helps me modulate better. If you're grabbing a handful, it's too much. Brakes are not boobies...you just need to grab a little. :razz:

Mokupono · 04-07-2007, 12:41 PM

Problem solved - sorta:

I forgot my VFR has a linked brake system - the pistons are activated on the rear brake when the front brake is applied. It's about a 70/30 split. For the most part, I don't have to use the rear brake when stopping or slowing down. I've become so accustomed to my VFR that I've transferred my braking habits over to the S3. Guess it's time to start learning how to use the rear brake afterall...

Thanks for the advice folks!

AJM216 · 04-07-2007, 02:00 PM

If you grab the front brake rapidly you run a good chance of the front locking and slipping from under you.

I grab and squeeze and increase the pressure as the weight transfers towards the front of the bike which weights the front tire down increased the traction and allows for increased braking pressure. With practice it can be done very quickly and smoothly.

I use both brakes but I use the rear brake lightly.

PaloAlto · 04-07-2007, 05:13 PM

What AJM said. It takes an eye blink or two for the weight to transfer to the front as you apply the brakes. If you clamp the brakes full press in a flash, the wheel can lock before the weight transfer happens. Most reasonable tires ought to be able to hold enough to produce a stoppie when the brakes are applied just a bit gradually and nearly the entire weight of the bike is creating quite a bit of stickiness between the front tire and the road.

All that being said, several months ago, I hit the front brake in a panic stop and felt the front end squirm all around and heard the tire squealing. I did have time to think of slightly easing off the brakes but was probably lucky not to go down. And I did stop in time.

IMO, maximum braking occurs when the front is just at the limits and most of the bike's weight is transferred to the front. In that condition, the rear wheel has little to no weight on it and can't help much in stopping. Also in that situation, the rear is much more likely to lock up (much sooner than you've experienced before). If it locks, you can find the rear end coming around on you and you're most likely toast.

Bern

Speed3 · 04-07-2007, 05:19 PM

That's why you want to use the rear in conjunction with the front, so you don't have that drastic weight transfer. Read Twist of the wrist, which explains braking succinctly!

AJM216 · 04-07-2007, 10:52 PM

I have Twist of the wrist #2

Its a great book, there is so much info in there.