I’m using a aluminum frame with 8 speed claris on it, cost me around $450 brand new. I have toying with an idea of upgrading to 105 and put in a thread here asking for opinion. Most feedback I had is that it wont make much difference or no difference at all. Below the is the link of my thread
Now on the part of the bike fitting, this is very critical. I had a problem on my indoor bike and its a very frustrating. Again, folks here are quite helpful ,to summarize, I finally did another bike fitting on my indoor bike and my problems goes away. My advise is fitting is not necessary but if you experience any discomfort then you should consider it or otherwise it will ruin your enjoyment
That’s my 0.02 take