In reply to no_more_scotch_eggs:
The Estate have no problem with leaving bikes at the Pony Shed as long as they are not put in their store section (the shackled door part on the right) as they keep some of their stores in there.
The walking path to the bothy from thr Pony Hut goes up the left hand side of the river, it does not have any river crossings, not generally used by cyclists as its rough and boggy and steep in places.
The Estate track goes up the Right hand side of the river but involves at least 6 crossings, two of which are difficult in a Landrover.
I have met many cycists who come up past the pony hut on the right hand side, clearly dependant on the river level as you would expect but most who do choose to leave their bikes at the Rowan Burn ( NN 934 796) crossing and walk in from there as it involves no more crossings until the wee crossing at the bothy. Its about a mile from the Rowan Burn to the bothy
PS I`m the jannie for the Tarf with the MBA