Across the pond in England, they call it a winter bike.  I call it a rain bike, my dedicated, “better than 15% chance of rain” bike… because not only was the good bike expensive, replacement parts are freaking ridiculous.  We call it a rain bike over in the US because they don’t get snow in the UK like we get snow, and there’s no riding a road bike in the snow.  Skinny tires are hard enough in the rain, dude!

The quintessential modern American Rain Bike

Ideally, the responsible way to pick a rain bike is to relegate the old A bike to rain bike status when you get a new A bike.  At least that’s how I did it until I bought my Specialized.  

My first rain bike was a Cannondale, all aluminum with a chro-mo fork…  Riding on an actual railroad rail would only be slightly less comfortable:

I could still make this beast average 20 mph though

Ultimately, the rain bike will be set-up quite close to the A bike – and thus why I like relegating the old A bike to rain bike status.  The closer the two bikes are in set-up, the more seamless it will be to transition between the two when the weather has a chance of getting nasty.

Now, say money wasn’t an object (it is) and I wanted to keep the Trek as an heirloom bike, updating the components.  My A bike is a Specialized Venge:

It just so happens that I know the next best thing to a Venge is an Allez.  There are minor differences of course, but I should be able to match the set-up on the Venge easily.  Let’s say I had a Tarmac for an A bike, I would go with a Secteur or Roubaix.  Those pairings in Specialized’s line-up match up in geometry fairly close.

Now, let’s get into how I know this, because most people won’t know how in God’s name to figure out which geometries work within a bike line:  I took a factory photo of an Allez, made it transparent, and placed it over a factory photo of a Venge.  The only difference to work around is the head tube height on the cheaper Allez models.  Now, if you have a shop owner who builds frames, they can look at the published geometry numbers….  I don’t have the time to apprentice for him so I can learn how the numbers work.

 Beyond that, because my rain bike has a vastly different geometry from my A bike (they’re even different sizes), I transferred the numbers from the A bike to the rain bike then took both bikes to the shop to have them compared.  I’m as close as I can get the two bikes.  I paid attention when the Trek and Venge were fitted to me, so I know what to measure and how to change the set-up.  Simple as that.

One more thing to consider….

There’s a neat reason I like my 5200 for my rain bike:  Easy Access Repairs.  I have completely stripped down and put back together my Trek.  I can change a brake or shifter cable in minutes.  I have internal routing on the Venge so it’s a little tricky should a cable fray while I’m up north on a road trip in the middle of a four day tour.  This is a tiny point, though.  Barely worth mentioning, but still, a fair point indeed.

In the end, I want my Venge to operate flawlessly for as long as possible so I prefer to have a rain bike should we be heading out under a chance of rain.  The rain bike takes the abuse so the A bike can shine. 

Worse case scenario, and this is what I really appreciate, with a rain bike in the stable I never have to miss a day on the bike with my friends should the A bike go down and have to spend some time at the shop for a repair.

Of course, there is one other non-option:  Take a day off every time you think it’s going to rain…. but that’d be silly.

UPDATE:  Ian, in the comments section, offered that a good idea for a rain bike is to go with a cyclocross bike.  This way, gravel roads are opened up as well.  It’s an excellent idea.