Amtrak's Pacific Surfliner train runs several times a day between San Diego and San Luis Obispo and allows you to walk on board with your bike
as long as you added a bike reservation to your ticket (free). When purchasing your ticket on line, at the lower right hand corner of the ticket you are buying, there will be a drop down to reserve a bike or two with your ticket. They will not allow you to board with your bike unless you do this. I have seen them leave people at the station. However, so long as you make the reservation, you're good to go. The space for bikes is usually limited (though I have occasionally taken Surfliner trains where I had to lift my loaded bike up into a cargo car- I just take off two panniers and my handlebar bag and bring them to my seat, no prob).
At least on the Surfliner, I've never heard anything about the bike counting as a piece of luggage. I simply get on with my loaded bike and carry my handlebar bag with me to my seat. They're not counting my panniers or anything.
If you want to take Amtrak north of SLO, you need to take the Coast Starlight train which is quite different. The Coast Starlight runs all the way up/down the west coast, once daily, and requires you to box up your bike. I've never taken the Starlight but have done the Surfliner many times for week+ tours or overnighters anywhere from Ventura-Ojai-SB-SLO and really enjoy it.
Last year I took the Surfliner to SLO in mid-March and spent 10 days bumming around from there to Big Sur, back and forth all over the place, with no agenda and had the time of my life. It got chilly at night (low-60's day/low-mid 40's night) but I managed with layers and a thicker sleeping bag. In fact, I don't think I've had a good night's sleep since I returned home. The sky got threatening a few times but never delivered. Besides, as a life-long Southern Californian I like a little texture in the sky. It was off-season so it was quiet and the hills were greener than my first tour from Monterey to SLO the previous May.
Originally Posted by CommuteCommando
I don't know what the cycling is like between Ventura and Santa Barbara, but the drive is really nice. I think, but am not sure, that bikes are permitted on U.S. 101 North of Ventura to Carpenteria.
The section of HWY 101 between northern Ventura (Mobil Pier) and Carpenteria (Bates Rd) is currently being widened. A separated bike path is under construction (we'll no longer have to ride the freeway there!). Currently, however, bicycles going in either direction must ride on the northbound bike lane on the freeway. They've put up k-rail barriers to separate the bike lane from the rest of the fwy but the section at La Conchita is still pretty harrowing. I haven't been in the area lately as I've been busy and live in L.A., but I grew up in Ventura County and am very excited about this. It will greatly improve mobility between Ventura and Carp/SB. More info here:
http://www.cibike.org/news-events.html