I have a hybrid-style bike (Dawes Discovery 301) with a Shimano Alivio/Deore gearset.
After a recent ride I noticed that the light-coloured t-shirt I was wearing had been speckled with oil around the stomach area (and nowhere else). I later gave the bike a thorough clean, making especially sure that there were no traces of oil around the handlebars, headset and front derailleur.
However, on the next ride the same thing happened again, although to a slightly lesser extent. After cleaning the bike a couple more times the issue still occurs, so the oil appears to be squirting up from somewhere, but I don't know where.
I've had this bike a couple of years but hadn't noticed this issue before as I usually always wear a dark-coloured top when going for a ride. After inspecting the black jacket I often wear, I can see that it does have some oil stains speckled around the same area that my t-shirt was stained. So this has probably been happening for some time and I just hadn't noticed it before...
Does anyone know what might be happening here and how I can stop it?