Climbing when wet

Took a diversion on way home. Hill, cobbles, avg 11% with a 15% ramp half way up. Not a great idea once into the more sheltered bit which was still wet and I hadn't thought about. Bad idea - back wheel not biting. Scared the **** out of me. Bounced on the saddle to get some traction. Fortunately managed to put enough weight down and get over to the dry stretch.

Wheelie up the hill!

No seriously, if you apply the same technique to riding up a steep hill as you would to a wheelie, you will put all your weight over the rear and the correct pressure over the pedals, just don't pull up on the bars, pull back and don't kick the pedals to start off.

Reduced tyre pressure will assist but then who actually needs to ride about on anything over 70 psi anyway, save that benefit for racing or a big long sportive.

Gears do matter as well, if this is a regular route, maybe you want a different rear sprocket if possible. You could go further looking at crank length and front rings but then you could also look at frame profiles and stem length which are all costly. Just a rear sprocket change would do.

Only other thing is commitment to suffer...lots.

Sorry I can't give advice on this because the only climbing I do whilst wet is out of the bath

I always pull up MrBLH, same as when on the MTB. Its more efficient.

Its a case of getting your self weighted correctly thats all.

I have noticed some roads are worse than others, i.e fresh tarmac is slippy.

Yep, sit up, head up, heels down.
If you can position your hands on top of the bars, not on hoods, so much the better, as that lifts your body upright a bit more. If it does get too steep to keep the cranks spinning without standing up, just try to keep your weight back a bit and ignore the natural impulse to lean forward over the bars for more power.

Think I'm right in saying that ideally, cyclists should always stay seated on climbs. Better traction being the main reason. It's just that most of us mortals need to stand up occasionally on the really steep bits and/or to use different muscles. Or to launch devastating, Contador-esque attacks, obvs.

What pressure are you running in your tyres? I cycle a 25% climb on the way to work sometimes and get the same problem, I did it on Saturday while racing a hill climb and dropped tyre pressure from 120 to 90psi. It gave me a lot more grip, even when out of the saddle.

I've read that a combination of remaining seated and keeping some of your weight over the rear wheel combined with a smoother pedalling technique is the way to do it (as frequently practised by skilled MTB riders trying for grip on steep climbs).

If you stand up then you're unweighting the rear which means the wheel is more likely to slip. best to stay seated and make your pedal stroke as smooth as possible. I think the most important skill to master is anticipating when it's going to happen...