Cycling Weekly:
"Riders such as Marcel Kittel have spoken out against this practice. The German prefers not to take strong, legal analgesics that can have side effects, including drowsiness.
“The young generation has a very clear idea of what cycling should be,” he says. “There are some painkillers in cycling which are still allowed. I’ve never tried them, for example Tramadol, but I’ve heard how it works. I’m not sure it makes sense to use that in a 200km race, in a stage race, when it’s maybe hot and very exhausting. I think you’re not clear in your head when you take such a painkiller.”
Dr Hans Geyer of the World Anti Doping Federation has also questioned the ethics of using painkillers. In an interview with the BBC in October 2012 he said: “It is a grey zone. In my opinion painkillers fulfil all requirements of a doping substance because normally pain is a protection mechanism of the body.
“With painkillers you switch off this protection system, like if you switch off fatigue, which is also a protection mechanism of the body.”
Read more at
http://www.cyclingweekly.com/fitness/training/science-suffering-121058#JoytZiukJWkYYYgL.99