From the quick search I’ve just done, I don’t think anyone else has posted on this yet. But surely I’m not the only one who is cursed by the steadily sinking saddle?
It’s where you go over a bump and suddenly find you are sitting a notch lower than you were before. Once it starts, it just carries on descending and if you don’t want to be sitting below your knees you have to get off every couple of hundred yards and raise it. I thought at first it might be a question of where the clamp is positioned: if you twist it round to a certain point, you can close it beyond 90 degrees. But actually that makes no difference. And whereas this used to happen once in a blue moon, it now occurs with horrible regularity, maybe one journey in four lately.
It’s not a minor irritation, it makes a bike nigh unrideable if you’re reasonably tall and need a high saddle setting.
Very easy to sort out: when you unclamp the saddle, twist the nut on the opposite side and then reclamp it. That’ll make it really tight and the saddle will not slip at all.
Another problem it solves is the (really quite dangerous) swivelling saddle syndrome!
It’s easy to check whether you’ve tightened the nut enough – just try swivelling…if it turns when the clamp is locked, unclamp it and tighten it a little more. Usually you don’t need to tighten it more than about a 1/4 turn.