Chir Mhor stands at the head of Glen Rosa and Glen Sannox in the Northern end of the Isle of Arran. Seen from Glen Rosa, the mountain presents a wonderful classic peak shaped profile with the granite sheets of the south ridge descending from the summit.
The summit can be reached from just about every direction. For walkers, the best ascent is the west ridge, which is served by a path from Glen Rosa. High quality 5 to 10 pitch climbs from VDiff (5.5) upwards can be found on the North and South sides.
The easiest way to Arran is to catch the Caledonian MacBrayne ferry from Ardrossan harbour to Brodick, which takes about 45 minutes. Ardrossan harbour can be reached by car (cheap parking at the harbour) or train from Glasgow Central (which are timetabled to meet the ferry). As Arran is a small island taking a car across is expensive and pretty pointless.
A taxi is the easiest way to Glen Rosa. There is a taxi rand opposite the ferry terminal in Brodick. Two of the taxi drivers live near the trailhead which can be convenient for the way back! The taxi will drop you off near the trailhead.
A bus service also runs from the ferry terminal but doesn't go as far and requires a bit more knowledge of when to get off! The trail up Glen Rosa starts as a track and is fairly obvious. After about an hour and a half of fairly flat walking up the glen, the path splits in two. The left fork takes one up close to the South ridge and some of the best climbing.
No red tape that I know off. If wild-camping, do so up the glen (National Trust land) and not near the campsite. There is a woodland regeneration scheme partway up the glen. Camping there would be a bad idea.
I have always found the best weather in May and June. Because it is quite low and far south, it is probably possible to climb anytime it is dry, as the rock is so rough. Winter climbing is a possibility here, though conditions are very fickle due to the lack of height, proximity to the sea and being far south.
Campsite at the trailhead (don't know the price). Wild camping is allowed up the glen