One way to climb this mountain is by taking the second road to your left on the Dublin side of Kilbeheny where there is a signpost marked "Galtycastle".
Follow this minor road uphill ignoring the turn-off to the right (also signposted Galtycastle) and taking the left hand fork up a cul de sac at the Y junction after it.
After travelling a further 2 kms on this tarred road you will come to a locked gate. Parking here is very tight for even one car on the roadside.
Walk through the gate and over a small concrete bridge to the left. Follow a rough track past a shed and up the Blackrock river valley to its end.
This road was used as an access point for the turf cuttings on the mountains surrounding it during the Second World War. the turf was used to fire the boilers in the nearby Mitchelstown Creamery.
Then walk north east uphill to the col between Lyracappul and Knockaterriff Beg and from there to the summit.
Descent from Knockaterriff to the south is possible , however it is steep and slippery so care is needed. Linkback: https://mountainviews.ie/summit/121/comment/4881/

This picture is taken from the source of the Pigeonrock River which runs between Knockaterriff and Temple Hill. The river is deeply incised further down this very quiet valley. To the left is Knockaterriff, while you can see on the right towards the top of the picture, part of the long ridge which extends SE from Temple Hill. On this occasion I reached this area by crossing this long ridge, starting from near Benard which is an interesting, solitary place in its own right. However I expect you could reach the Knockaterriff area more directly by going up one of the roads that lead north off the main road near Kilbeheny. Linkback: https://mountainviews.ie/summit/121/comment/540/

The valley between the Knockaterriffs (on the left in the picture) and Lyracappul South East contains this stream, “Blackrock River”. A ruined track, marked on the OS 1:50k map, crosses it to the left of the picture and then does a zig-zag onto Lyracappul South East (lower right of the picture). Like other south facing valleys on the Galtees this one is more V shaped than the valleys on the north side. Note the outcrops on the left, which are under Knockaterriff. Linkback: https://mountainviews.ie/summit/121/comment/541/

A perfect winter's day to climb two peaks that are off the main Galtees ridge and that I hadn't climbed before. I parked at a small grass layby at grid ref R858 201 A (see track info too). The ascent of Knockaterriff from the south is very straightforward and at a fairly easy angle. I descended into the Blackrock River valley north of the summit, omitting Knockaterriff Beg, (having climbed it before!). The descent from Monabrack to the Blackrock valley is quite steep though the going is good. Linkback: https://mountainviews.ie/summit/121/comment/15292/

This picture taken from Farbreaga in the western Knockmealdowns shows Cnoc an Tarbh as a prominent lump at the centre of a wider loop. There are deep sided valleys east west and south. In the picture the col connected to Lyracappul and Temple Hill is hidden from view. The sharper sided glen on the left (west) of the lump is Pidgeon Rock glen. You can make a nice loop around the surrounding peaks, including Monabrack. Linkback: https://mountainviews.ie/summit/121/comment/23427/

We used Jackill's route above in reverse, parking at a grassy verge at R866191 B and walking to the end of the rough road. we climbed Knockaterriff from the start of Pigeon Rock Glen in a straightforward slog upwards, then crossed Knockaterriff Beg to reach the steep slope of Lyracappul. After admiring the views northwards over Aherhow from Carrignabinnia, we came down the shoulder to reach the col between Carrignabinnia and Monabrack where we picked up the turf track described above. This is a lovely descent, initially to the Black Rock river valley and over a ford to contour along the side of Knockaterrif. Although the track is indistinct on the map, it is well marked on the ground. The track picks up a beautiful sandstone wall and gives excellent views over to the Ringfort - cashel described in the Historical Environment viewer on maps.archaelology.ie. This is at R857 206 C and is marked on Barry Dalby's Galtee map. Linkback: https://mountainviews.ie/summit/121/comment/23494/