I usually cross by car, and have never crossed on my bike. I know it’s free for bike, but which toll booth do I use and is it OK to filter all the way to the front?
Bikes are free on the M25 Dartford crossing, just go to a an isle where you pay the person and they will let you through.
It is a very dangerous area with loads of lane switching etc - so just take your time, don’t try to be clever, and don’t try to beat the barriers - a biker was decapitated there once.
I took this road once, didn’t even know we’ve got something like that in London 
Was afraid because didn’t have any cash with me but motorbikes are free.
The guy at the gate just told me that I should use other gate for motorbikes because he has to open it for motorbike drivers manually every time.
Anyone knows which one is the right one ?
According to the Dartford Crossing website you should use any maned booth and wait for the operator to open the barrier.
Thats right - you have to actually stop aswell before they’ll raise the barrier for you (as in they wont look out & see a bike coming and just raise it, some kind of rule about you stopping, putting your foot down).
That rule is because a rider got decapitated.
And be extra careful when you start off again, because you’ve pulled up just where millions of vehicles stop and drip oil, hydraulic fluid, screenwash, etc, etc. Especially in the wet it can be like an ice rink and it’s a very public place to bin it! 
Is that experience talking Micky? 
First time I used the auto booth…no. no. the guy came out and wrote down my reg, I asked him if there was a problem, he said no but had to write down the reason for lifting the barrier without charge! So I now always use any vehicle booths.not auto, and the guys on the booth hold out an arm untill the light turns green then lets you go.
I always eye-ball the operator.
I think that makes him think that I’m paying attention!
If you do that and sidle up to the booth very slowly, you probably won’t have to stop.
Yes, only it was in the early 90’s on my first CBR at the Severn Bridge (the old one) not Dartford, and I didn’t exactly bin it. Slowed right down, barrier went up, I opened the throttle and the back end went sideways like a speedway bike. I stayed on but don’t ask me how.
i once went to the auto toll gate by mistake, after i had been using the bridge in the car for three weeks i was so used to going there. couldnt back the bike up cos i had a car up me arse and the fella working wondered over and said “youll have to move it mate, i cant raise this barrier myself” i said "well i havnt got a quid on me, the car behind is up me arse and i dont have reverse gear, what do you suggest?"so he stuck a key in a switch on the barrier and up it went. muppet!!
and why is it that every day i use the bridge on the bike, the toll booth staff are either men or right old growlers, yet on the rare occasion i use the car and have the missus and kids with me, i pull up to britains next top model???
so er to sum up, use any gate but the auto toll, filter right to the front, dont go behind a foreign lorry, go slowly, eyeball the booth operator, and glide right through, dont forget the “cheers mate” as you pass.
and watch out for the twats who use the auto tolls on the far right, then decide they have to use the very first exit thus cutting everyone else up!! twats!!
I tend to find it is best to wheelie past the line of cars flipping them the bird.
And is twats doing just that that have made it hard for us who attended the meeting with the Dartford Crossing management to persuade them to give us our own lanes.
Muppet. 
I’ve never had issues with the Dartford Toll as a biker. Just used manned booths and really keep a sharp eye out for diesel/oil spills and other road users wishing to nip across all lanes in a panicked state of “where am I going!!??”
Love the sound of my Triumph through the tunnel!! Pootle at 40mph in 3rd, drop to 2nd and nail it! HOOOWWWLLL!
If there’s more than one bike at the barrier, they will signal that only one can go through at a time. You have to wait for the boom to come down and then raised again for each bike. I guess this is a safety precaution.
When I find myself with other bikes at the barrier, I will hang back and save the time and hassle of being given the instruction.
-Steve