I tried to post this in 'other sites and locations' since I don't think this is in a WS or NP, but I get this message when I try and post there: "NOTE: You are posting the message as a 'Guest', you can not edit the message or delete it".
This is a short 4km trek which is probably not worth a special journey from Bangkok, but if already in Ratchaburi or Kanchanaburi towns it's only just over an hour to drive. I did it from Kanchanaburi. The trail starts near the road to Khao Krajom Viewpoint, which is a great view across Myanmar, but a terrible road, you need a 4x4 or a dirt bike for that road.
The trail is in good condition, there are no leeches, it's free (no staff or tourist infrastructure), but it can get very slippy in rainy season.
I tried this last year from the other side of the mountain, and that route did have leeches because it goes up through a moist valley with lots of streams everywhere. This route is going up through dry bamboo forest. That trail from the other side was not so clear and I made it to within one valley of the summit (about 1km away) by 4pm and didn't think I could make it before dark so turned around. This time when I got to the summit (a different way) I saw a less obvious path going down from the summit and I'm fairly sure that path connects up with the one I tried last year. The yellow path is my 1st attempt. I think I had the trailhead correct but took a wrong turn fairly early on - the purple path (approx) is where I suspect the trail should go. The red path is the easiest route I think and the GPS file for it is below...
The trailhead for the purple path is at coordinates 13°33'48.7"N 99°12'33.1"E After a few 100 metres going down, you cross a small bridge and go past a tree replanting initiative which has been sponsored by a company that has erected a big sign there, I think SCB or maybe another bank, I can't really remember. It was at this tree planting place I think I went wrong, I took a small trail which I assumed was the trail, but if I'd carried on going through the tree area maybe I would have stayed on the correct (wider?) path. Presumably there must be quite a few people using that trail otherwise SCB wouldn't have spent money putting a sign in the middle of nowhere.
Anyway onto the red path. The trail is easy but getting to the trailhead needs some directions. Off the 'main' road you want to turn right onto soi 2.
Drive down here slowly and look for the green sign on your right. If you are in a car, park it somewhere around here and walk.
Go up there not too far and you will come to a sort of end to the road and you will see an arrow pointing up to the trail, stuck on a tree, I think red and white from memory. That's where the gpx file starts from.
Short but steep!