Cats-eyes and corners

**CookMySock** · 19th October 2009, 14:30

Growl, just an "OH FUCK" moment on the way home.

90-100k , left hand corner, right-hand half-lane, front tyre clips a catseye and WHACK!!! Front end does a MAAAAAASIVE twitch and a swing to the left. What the fuck is up with this shit? It felt like I hit it with my fucking rim or something. I pictured teeth on tarseal there for a second. Not fucking amused.

Way too much progressive damping is my call.. but then I can hit them upright without care or consequence. Or is clipping catseyes while cornering not done?

Anyone care to elaborate?

TIA,
Steve

**Rodney007** · 19th October 2009, 14:34

no idea. probably thousands of variables
due to angle of bike, the face of the cats eye, tyre temp , suspenion setup, where your body was, your riding a ho-bag, temperature of the cats eye and then the road surface undernieth it, what tyres you were using, the elevation of the corner, your riding experience, using a steering dampner, the condition of your steering head bearings, your bikes steering rake, your weight, your rim/tyre weight.. BLAH BLAH BLAH ... just try not to hit one next time?

**saxet** · 19th October 2009, 15:00

At a guess you may have hit the catseye with the sidewall of the tyre thereby put the impact onto your rim.Should be o.k. but have a look at the rim for poss. damage.

**NighthawkNZ:Me** · 19th October 2009, 15:32

Originally Posted by saxet

At a guess you may have hit the catseye with the sidewall of the tyre thereby put the impact onto your rim.Should be o.k. but have a look at the rim for poss. damage.

if he did hit a cats eye on a right hander then that is a very poor line and possibly have the bike was over the centre line including his head...

**mossy1200** · 19th October 2009, 15:41

Done it mayself on the Hill as there was a bend that starts as the dual lanes finished and expected to see rim damage.Side walls are very firm when lent over and it felt like zero give on the cats eye.

**Robert Taylor** · 19th October 2009, 17:08

Many of the above suggestions are valid but its also because of hydraulic choke off, there simply isnt enough flow rate in the standard front fork compression pistons. Aside from losing ride height control if you completely removed the compression shim stacks the forks would still jolt. A good piston and valving design will take away a lot of the pain ( but not all of it as you still need to feel connected to the road )
It can also be because the fork springs are too soft meaning the front end rides too low in its stroke.
I have a giggle quite often when people say adjust the clickers, the clickers do not vary the piston port size!!!

**BMWST?** · 19th October 2009, 19:56

never run over em whilst leaned over and never ever run over them leaned over in the wet,,

**FJRider** · 19th October 2009, 20:01

Originally Posted by BMWST?

never run over em whilst leaned over and never ever run over them leaned over in the wet,,

Running over opossum skulls in a corner have a similar effect to that as well. A half inch movement of the front wheel sideways ... feels like a mile and a half ...

**CookMySock** · 19th October 2009, 20:14

Originally Posted by Robert Taylor

[....]its also because of hydraulic choke off

Yeah thats the first thing that occurred to me. I'm kinda sick of its' highly progressive suspension actually. It's just fucking rough. Yeah yeah I know the solution.

Originally Posted by BMWST?

never run over em whilst leaned over and never ever run over them leaned over in the wet

This the answer I was hoping for. It seems this is something I should not be doing. At all. Yes I know, its lazy - and I should put my fucking wheels where I choose, and not where they end up. I am surprised I did not know this. I have not heard this discussed before. Maybe because most people apex hell out of corners and don't ride anywhere near the outside of it.

Originally Posted by FJRider

Running over opossum skulls in a corner have a similar effect to that as well. A half inch movement of the front wheel sideways ... feels like a mile and a half ...

It sure did. If I didn't have some nice Michelin PR2's on there, I bet I would be spitting out teeth right now. It was all over in a blink, as it seems it does, but I was shocked to discover I was upright.

Many thanks Guys.

Steve

**p.dath** · 19th October 2009, 20:32

Just read an interesting piece of of Keith Codes "Twist of the Wrist II" which talks about exactly this (hitting objects while cornering).

It talks about the gyropscopic effect of the wheels (obviously when they are spinning). To cut the article short, the gyroscopic action of the wheels opposes anything that tries to move them out of their line (just like countersteeing). And when you do it destablises the bike, until the force that tried to move the wheel stops, and then the gyroscopic action stops trying to oppose that force, and the bike will re-stablise again.

Don't ask me questions about this. I'm just learning about it ...

They only really important tip I can give you from the book is don't close the throttle. Doing so reduces the rear contact patch, which increases the chance of a slide occurring. You need to have a small amount of acceleration (0.1G to 0.2G) to counteract the effect (which causes a 60/40 countact patch ratio which it says is the optimum ratio for traction while cornering).

**CookMySock** · 20th October 2009, 07:50

Originally Posted by p.dath

It talks about the gyropscopic effect of the wheels (obviously when they are spinning). To cut the article short, the gyroscopic action of the wheels opposes anything that tries to move them out of their line (just like countersteeing).

Going by the hellava WHACK it gave, I'd say the forces involved were all to do with solid sidewall hitting solid catseye.

Originally Posted by p.dath

They only really important tip I can give you from the book is don't close the throttle. Doing so reduces the rear contact patch, which increases the chance of a slide occurring. You need to have a small amount of acceleration (0.1G to 0.2G) to counteract the effect (which causes a 60/40 countact patch ratio which it says is the optimum ratio for traction while cornering).

That is all talk on the cereal box - I had no say in the matter. It was all over in a millisecond. It is faulty thinking to consider I could have done anything whatsoever, except to not hit it to begin with.

Try it yourself if you dare. I certainly won't be doing it again. I don't like apexing while I am touring - I think it is poor discipline, but the outside of fast left-handers is not an appropriate place to position the bike. The tyres go on the best seal - where the bike goes is unimportant provided it's in my lane.

Steve

**MyGSXF:Me** · 20th October 2009, 08:17

Originally Posted by DangerousBastard

90-100k , left hand corner, right-hand half-lane, front tyre clips a catseye and WHACK!!! Front end does a MAAAAAASIVE twitch and a swing to the left.

Way too much progressive damping is my call.. but then I can hit them upright without care or consequence. Or is clipping catseyes while cornering not done?

Originally Posted by DangerousBastard

It seems this is something I should not be doing. At all. Yes I know, its lazy - and I should put my fucking wheels where I choose, and not where they end up. I am surprised I did not know this. I have not heard this discussed before. Maybe because most people apex hell out of corners and don't ride anywhere near the outside of it.

Originally Posted by DangerousBastard

I had no say in the matter. It was all over in a millisecond. It is faulty thinking to consider I could have done anything whatsoever, except to not hit it to begin with.

I don't like apexing while I am touring - I think it is poor discipline, but the outside of fast left-handers is not an appropriate place to position the bike. where the bike goes is unimportant provided it's in my lane.

To be honest I find a lot of your posts rather disturbing.

You hit a catseye, because of your poor line choice. If you ran wide in the corner & hit the centre line where the cats eyes are, then you were going to fast into the corner.

You had every say in the matter.. YOU are in control of your bike.. not the other way round!! you need to be in the correct gear, having done your braking before the corner while still in an upright position, & be on slight positive throttle when you get to the corner. Then roll the throttle on when you can clearly see the exit point of the corner

Where the bike goes, in your lane is very important!! & it is you who is in control of what happens!

Bikes don't crash.. people crash!!

I would strongly urge you to find a good rider training school up your way & book in for a course!

**FROSTY:Me** · 20th October 2009, 08:29

I was unlucky (or just dumb) enough to do exactly what DB did a few years back.
Overtaking a very slow moving truck on Piecock hill. I touched a catseye with the front wheel then hit a mudpatch with the rear wheel.
Ended up on my arse sliding towards a very long drop.
Hindsight is a great thing innit?
I thought I could see clear ahead Guess I was wrong.
Mistakes sometimes happen--I guess ya just learn from em

**jonbuoy** · 20th October 2009, 08:52

Erm is it just me or is it stating the obvious to not run over anything when your tipped over? Rocks and dead animals can be unexpected but a line of cats eyes? I try not to hit them in a straight line if I can avoid it.