I purchased a Specialized Roubaix Comp 2018 last year, I was not intending to purchase this bike but Evans had a 40% off sale and the deal was too outrageous to pass. I was originally looking at bikes with Shimano 105 groupset because I was given a friend's old stages 105 left hand side power meter. This power meter has been sitting around for months and months. I recently got an indoor trainer and have started 'properly' training. Reading power has been a big step up in my understanding of pacing and I'm very keen to get a power meter on the bike for when I'm out and about (once the world lets us out of lockdown...).
My problem is that I have no idea if my bike will take an Ultegra crankset. The currently fitted crank is a
Praxis Zayante. The bottom bracket is not explicitly stated, most sites say "Included w/ crankset" (source: specialized).
Looking on the bike itself, the BB has external cups and say M30, so it looks like the BB is the M30 THRU BSA Threaded.
Now I understand very little about bottom bracket standards and honestly reading about them has confused the situation for me more...
Do I simply just unscrew the Praxis and fit a Shimano Ultegra BB such as the 6800?
Will my frame fit a different bottom bracket? I could not find any numbers for my frames BB sizing. Do these bikes adopt a standard or are they all slightly (stupidly) different?
The Shimano BB looks very cheap, this is a luxury/performance bike and I'd expect such a crucial part to cost a little more, are there better (less creaky) options than the vanilla BB for not much more?
Authors note: I recognise an Ultegra crank with 105 LHS is scuffed but cheaper than getting a 4iii for my Praxis (which is seemingly unavailable)
Edit: Here is a picture of the external cup on the LHS