"road grooves" or "drift lines" = dangerous?

jdd

Maximum Pace
Hardest Crash
Jul 26, 2008
2,512
639
133
Kanazawa
#1
Hello,

I think that communicates what these are: the grooves/lines in roads here in certain places. They're on certain curves or sometimes just before entering or just after exiting a tunnel.

Just how dangerous are they?

On straights they don't bother much at all, but there are two spots on one of my courses that they're on fast downhill curves. Tho I haven't been particularly scared, they feel squirrelly enough that I don't go as fast as I could--holding it to about 50km/h, when 60 might be possible. (Tires are 25, if that makes a difference.)

Comments?

(And here's a nice ride if anyone's ever in Kanazawa.)
 
Jan 14, 2007
2,514
213
83
Noda
japanichiban.com
#2
My first week of riding and these grooves caused my first crash. Since then I've been very careful.
My bike was being guided to the right by the grooves but my body line was going left. I went down, Luckily I was going very slow.

These days if I find myself running a tangent to them, I just attack them strongly and try and run parallel or get right away from them. Sometimes they are cracks in the road or where two parts of road or concrete join. Sometimes they are on old roads where the asphalt has melted or deformed due to heat or traffic.

They can be very dangerous on narrow roads and all you can do is slow down and ride the bumps till the cars are away.
 

Wolfman

Speeding Up
Jul 31, 2007
631
18
38
Suginamiku
#3
Dangerous

Since running 20C on the bike, these road grooves are pretty frightening. I realised they can throw you off kilter, leading to wobbles. If they're there on a descent, then I'm sub 40km/h.

If it came down to a choice of road grooves or the concrete circles, I would take circles anyday. They give you the shakes, but they don't disorient you as much as the grooves.
 

Pucci

Speeding Up
Jul 12, 2006
283
1
38
Yokohama
#4
I HATE those grooves. My current set-up has a 19mm front tire with an eliptical profile and the tire slots right into the grooves. Very scary.

The narrower the tire and the lighter the rider, the more the grooves will mess up the steering. A heavier rider with 22mm tires might be able to do 50kph on them, but I would crash.
 

chazzer

Speeding Up
Nov 23, 2006
449
0
36
Bushey Heath, Hertfordshire
#5
Groovy baby..

Running 20`s at 11 bar or 160psi (Conti 4000`s) and I can certainly feel the occasional pick up, particularly rear tyre, but has not, as yet, prevented me from descending as quickly as I might otherwise do. Much more cautious over narrow and gravel-strewn goat tracks !

But better still - nothing beats smooth tarmac with a clear and visible exit line from a corner when you can clip the apex and give it full pelt on the way out :D:D

chazzer
 

jdd

Maximum Pace
Hardest Crash
Jul 26, 2008
2,512
639
133
Kanazawa
#7
Just rode that course with the grooves this a.m. and had less concern on the first curve than the second, faster one. Also, the first one is at least a few years older so the grooves have probably worn a bit more. At any rate, thanks for the replies.

And another thought--there may or may not be a national construction standard for the grooves, and even if there is, there's probably some variance across the country. Width, depth, etc.