Keep in mind that the time frame given for complete recovery from tendonitis might be optimistic. I injured my shoulder in December 2006, and am still dealing with it! I had severe tendonitis & lost a significant range of motion (had difficulty getting dressed even). It took about 2-1/2 months of PT to restore some range of motion, but pain was an ongoing problem for a lot longer. The problem is that we continue to do things in our everyday lives that aggravate the condition. I still have serious pain days, where I pop anti-inflammatories & grit my teeth to get through. Yesterday was one of them. So I know I'm not past it yet, and I still do daily exercises & stretches. My PT-person had the same condition in both shoulders some years ago. She said it took her 2 years to get past it, & she does daily exercises to keep it at bay.

The upshot of all that is, that even if you do the PT, you still might be left with serious pain issues that will keep you from fully concentrating & doing your best at your racing. Not sure I would recommend surgery either, because recovery always seems to go slower than the "advertised" time (in other words, write off the entire season). But if you go with surgery to fix the tear, I would get a 2nd opinion from the best ortho doc you can find, and maybe even travel to get to one who practices at a sports med facility.

Best of luck on this one.