Has this happened to you? It starts raining, and the next time you come to a stop sign your brakes don’t work. You roll through the intersection and thank your lucky stars no cars were coming.
Rim brakes and water don’t mix. When the rims and brake pads get wet, almost zero bike- stopping friction is created no matter how hard you squeeze the levers. At least for the initial dozen or so wheel revolutions.
The trick is to anticipate the need to slow or stop. Apply the brakes much earlier than normal so water is wiped from the rims and pads. Don’t squeeze too hard. Just hold the rubber against the metal like a squeegee.
As the water is displaced, be ready for suddenly stronger braking power. Back off your lever pressure as you sense this or you could lock a wheel and skid. At this point braking action is nearly the same as it is in dry conditions.
Ride defensively in the wet. Stay aware of everything going on around you. When you think there could be the need to brake, hold the pads to the rim lightly even as you pedal along. This won’t be enough to slow you, but it will wipe away water so actual braking is much quicker when it’s time.
Got disc brakes? You’ll have much better stopping power when it is wet, but you aren’t completely in the clear. Wet, slippery roads are just as slick no matter which type of brakes you are using. And the guy behind you might be riding rim brakes! Give yourself plenty of stopping distance when roads are wet.
Learn more:
Braking and cornering on wet roads
Carbon rims are even worse at stopping in the wet.
Ok more fear mongering over aluminium wheels and rim brakes; having ridden in the rain a lot it only takes ONE revolution of the rim for the rim brake pads to swipe the water off and start working. A rim is nothing but a large disk brake anyways, their virtually the same in concept, you have a pad and a aluminum surface, the only problem you would have with stopping in the wet using rim brakes is if you’re trying to stop while riding through a couple inches of standing water which would be constantly getting the rim surface wet and the pads having a difficult time swiping the water off. You can improve the efficiency of the brakes by changing the pads to Kool Stop salmon pads. Disk brakes have the same issue when they get wet, but due to the smaller diameter of the rotor the pads will swipe the water off quicker. The disk brake not working well when wet is obvious if you have ever been to a car wash, or drove through deep standing water, the brakes will not work well till you feather the brakes gently for about a quarter of mile while maintaining speed to dry the rotors enough for them to start working good again. You need to do the same thing with rim brakes as well.
“Disk brakes have the same issue when they get wet, but due to the smaller diameter of the rotor the pads will swipe the water off quicker.” If the statement is correct that it takes one revolution of the wheel to wipe off the water, then disc and rim brakes will behave the same.
My concern is that when riding in a group each rider should increase their distance to compensate for the wet breaking situation
Ok when I used to draft my companions I remember what it was like in the rain. WET and the rooster tail off that back tire. Moved you back without the thought of braking. Further, water is spun to the braking surface…. with discs that effect is not there. They stay dry by being located close to the hub and far from the road!
I’ve found that direct-pull (“V”) brakes work pretty well when they’re wet. After a short delay (definitely less than 12 wheel revolutions) there’s good brake function.
As I said earlier, sidepull brakes can work very good in the wet if you use the right pads, I use the Kool Stop Salmon colored pads and those pads grip wet rims just fine after the initial one revolution swipe (with an aluminum rim), but even during that first revolution those pads are slowing the bike down. I’ve been using those Kool Stop pads for many years going all the way back to when they were branded as Scott Mathauser pads (also rebranded as Suntour Superbe pads). When I bought my last bike in 2013 it came with Shimano black pads, those didn’t stop well at all in the rain, my first experience in the rain made me change them fast to the Kool Stop’s. Those Kool Stop salmon pads are the only pads that will stop quickly in the rain.
Some internet sites will say that the Kool Stop Salmon colored pads won’t stop as good when it’s dry out, I have not experienced that issue at all, in fact I found the opposite to be true, at least compared the factory stock Shimano pads that feel mushy; but for those that think otherwise Kool Stop makes a dual compound pad, half the pad is salmon colored and the other half is black, there is a dual compound pad called the Dual Mountain pad, there is enough salmon portion of the pad to make it very effective in the rain, there are also groves in the pad to swipe water away faster and to clean the rim with a rear turn up that allows the dirt to fly off.
Also the Salmon colored pads last a very long time.
I can’t write enough about the importance that the right pads make in the rain.