It is true that Bamber would be highly motivated.
That is why I do not believe if some of The Sea Wall or Farm Tracks were uneven, that would deter him.
I spend as much spare time as I can, cycling around countrylanes and bridleways and byways. I carry my bike over styles, fences and god knows what dozens of times a year.
This whole thing is a non issue.
Bamber had 3 valid choices...
Drive, walk, bike.
Walking would take the longest time, so probably not that.
Driving was the least discreet, so probably not that.
Cycling was reasonably inconspicuous, and relatively quick. And you can always get off and walk. So probably that.
He could of used any of the above three and not have been seen, but he probably used a bike.
Nothing else could ever prove or disprove any of that.
He admits to taking his mothers bike to Goldhanger a few days before the murders. So the bike scenario is plausible.
Hanging out with an angry bloke from an internet forum under the cover of darkness is not something I'd recommend.