I want to get to San Francisco from Los Angeles. I've looked at a number of options, including cycling. I have never biked such a great distance before, so I consulted Google.
It says that the trip will take one day and nineteen hours. If I suppose I travel eight hours a day, that's like five or six days. Is that the least bit accurate in the real world?
That is a reasonable estimate, however there is more to it than that. First of all, you are not going to be cycling the way you would drive, i.e. on the Interstate. For your particular plan you are most likely to be wanting to follow Highway 1 up the coast. This road is bicycle friendly whereas the Interstate is not. This comes at a price - more miles and more hills.
If you look at Highway 1 you will notice that it passes through some areas where nobody lives. The Big Sur coast down to San Simeon is rather remote, and, if you are looking for somewhere to stay over in that stretch then there are not a lot of options. Obviously San Luis Obispo and Monterey have motels, youth hostels and camp grounds to choose from so you need to do that stretch in a day.
Pushing on from Monterey into San Francisco is doable in a day if you are fit, however, you might kick yourself later for not going round the aquarium in Monterey or not having a snoot around Santa Cruz. Therefore you may want to stay over in Half Moon Bay where there is a Youth Hostel in a lighthouse. Staying there obviously means you have a manageable trip into San Francisco and you will not have to arrive there in the dead of night, as you would if you had cycled 'robot style' all the way from Monterey.
I would recommend that you budget seven days and base your individual daily rides on where to stay. You also need to bear in mind that lots of cyclists ride the entire Pacific coast route so, if you stay over in a cyclist-friendly place en-route, you may find yourself meeting up with others that are taking your exact same route. They may have started off in San Diego and have already found their cycling legs, they may also appreciate having you for company, particularly if you can set pace up hills or do turns at the front to give them a slipstream. You then might prefer riding with them and decide to do the route with them all the way, throwing your existing plans out of the window.
I advise that you buy the map of the route from the Adventure Cycling Association. This will provide you with the information you need to make the most out of your ride, that is if you are doing Highway 1. That includes bike paths, where there are good places to stay and where the nearest bike shops are.
Route choice aside, take the miles, throw away the hours, other than as a crude comparison tool. Examine the route profile (however you can manage) and try to classify what part of the route is flat, climbing, congested, etc.
Use your personal performance in prior long rides to judge speed for each type, and do the division.
Keep in mind that, on an unsupported ride, you will spend time looking for food, looking for the loo, looking for a place to stay, and, generally, being lost. You need to figure that an eight hour day will only get you maybe six hours of actual up-to-speed riding in most cases.
Also understand that about halfway through the second day you'll begin to feel every bone in your body hurting and will have to slow down and take more frequent breaks. By the middle of the third day, though, you should have your "sea legs" and be doing a bit better, if you don't beat yourself up or short-change food and sleep.
You're doing 500 miles. Unless you're an exceptionally strong cyclist and the terrain is flat (which I know it isn't) doing that in 5 days is unlikely at best. Doing it in 6 is a maybe, and perhaps what you should plan for, but give yourself the option of taking an extra day (or two), or calling a friend to "rescue" you after 6. And plan at least 24 hours recuperation after the ride.
And don't forget the sunscreen!
Cycling speeds do vary greatly, and I'd advise to remember your average long-distance speed from a day of cycling and cut away a third to take the many unknowns and saddle soreness into account. When I cycle for half a day, for example, I usually average 15-20 kilometres an hour, so I'd expect 10-15 kilometres an hour or 100 kilometres per day for longer distances. That was close to my average on the one 3-day tour I made.
Make sure you match the terrain and street conditions, though. My above estimate was for hilly, towny European terrain. In the vast reaches of colonial America, you will probably be able to go faster.
In terms of that specific journey, 1 day 19 hours is 43 hours and if you cycled 8 hours a day then obviously that's going to be five or six days.
The key is that there's no one-size-fits-all answer. Touring cycling is all about the journey, less about the destination. Sure you could work out likely average speeds, but then you need to think about lunch? What if you find a lovely little roadside surprise and you take 2 hours instead of 20 minutes?
Then you need to plan sleeping, do you book ahead and risk having to rack up the miles in the dark? Or do you try and wing it, but then risk that last place for 15 miles being full and having to turn around or search around? Or are you fully self sufficient? In which case finding places to camp might be tricky.
The weather has a massive part to play too, your average speed in rain or drizzle or stinking hot will likely be lower than in a cool, dry, tailwind. (Check out this answer for some good information on generating a hill profile of routes, too - that's a huge addition right there.)
And you've never done a journey like that before? Well, that's a whole new dimension! Centuries are relatively easy to work up to. From there back to back centuries over two days are a short step. But this could be five?
Think of a speed, take some time off and round it down, I think @thiton's estimate of cut off a third sounds like a reasonable idea. And whatever you guess, you'll almost certainly be wrong, but I'm sure the journey will be memorable, so I'm equally certain you won't mind being wrong in the slightest.
