biketrials riding techniques...front-to-back wheel-swap
The front-to-back wheel-swap makes it possible to finish off a move on the rear wheel, even though you may have started or landed it on the front wheel. It basically starts from an endo.

1° Launch a fast endo and bring your knees towards the bars to absorb some of your momentum. Lean forwards and concentrate your weight above your front wheel. 2° Once you have transferred your whole body on the front, release the front brakes and roll off the bike forwards in one swift extension from the arms (that releases your momentum). 3° Finish off the move fully extended again, lifting the bars in front of you to maintain the front wheel off the ground after it rolled. As you stretch, the rear wheel ends up beneath you.
See the move in a video

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slow-motion demo by Olly
Go fast
The wheel-swap is easier when you launch it with plenty of forwards momentum, like doing a fast endo that would go over the bars if you didn't release the front brakes. Try it out on a kerb to gain confidence, then build it up on narrower edges. The trick is to shift your weight forward and above the front wheel (knees below the handlebar) and then whip the bike forward (the actual wheel-swap) by extending your arms while your body stays on the same spot.
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Front-to-back finish
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No room for the full bike
Just keep your body moving
It is like decomposing your forward momentum into small bits that you reuse in your own time. Once you understand the concept, you can even do a back to front wheel transfer on the reverse principle. Try it just for fun. Some guys will bounce off rails and narrow edges... Same technique, just bloody difficult. Although it makes it more difficult, you could do a wheelswap on the spot just by emphasizing body movement.
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Thomas Oehler on a smooth finish