I think Google's algorithm works something like this:
If the title of your page is "Discounted Bike Parts", your page topic score might be as follows:
- Discounted Bike Parts: 10/10
- Bike Parts: 6/10
- Discounted Bike: 6/10
So your title is more about "discounted bike parts" than it is about "bike parts".
But this does not necessarily mean that you want to make your title "Bike Parts" just so that you can rank for that exact keywords as a perfect match.
The reason for this is that Google does not want to display identical content in its search results. It does not want to display 10 pages with the exact same title of "Bike Parts". It wants to show some pages with "Discounted Bike Parts" and "Bike Parts for Sale".
It is important to have the keywords that you are targeting in your title, but you do not need to go overboard in trying to exact match the search keywords. Google will understand what your page is about.
There may be a slight ranking boost by having the keyword that you are targeting before your negative keywords. For example, "Bike Parts Store" might be better optimized than "Discounted Bike Parts" because the keyword comes first.
Ultimately, Google will try to rank pages that it thinks are the absolute best page on the internet for what the searcher is looking for. Optimizing keywords and keyword density to target a search phrase is important, but it's much more important that your page is the best page on the web for your topic. If Google believes that you have the best page for its customers when they search for "Bike Parts", it should rank "Discounted Bike Parts".