Normally Glassdoor under lists compensation for Bay Area positions, but I think this might be one case where selection bias is making it over-report.
I don't want to discourage anyone from following their passion, but I personally opted for a different professional job and volunteer as time allows at the local bike co-op. The delta in income more than covers the lack of pro-deal access.
I'll bet being a bike mechanic in SF is a lot like being a ski instructor in Vail, CO. Lots of people want to do it to barely cover the cost of living there, so wages don't increase. At least bike mechanic is a lot less seasonal in SF than ski instructor in Vail.