For the commuters out there....
 

...out of curiosity. Do you have a different bike that you use just for your weekly commute vs. the bike that you use for events (centuries, long weekend rides, etc.)? I have been commuting for the past 3-4 years, about a 20 mile ride roundtrip, but I have been using the same bike that I use for my centuries and whatnot. I have been thinking of investing in a 2nd bike specifically for the commute. Thoughts?

I currently use the same bike. A bit later then year when I hit 100 lbs of weight loss I am going to get another bike. My current "do everything" bike is a nice hybrid. When I get new bike it will be more of an endurance bike for longer distances. I'll keep my current bike for commuting and the occasional bike camping.

When I was a fair weather commuter I used the same bike, but now that I commute year round I have a dedicated commuter and a recreational bike. The commuter has a hard life and isn't necessarily ready to go out on a century or more at any given time. Plus in my current job the commuter has to sit outside daily, so it's not going to be a very nice bike.

I have two commuters and a club ride bike. I've ridden both commuters on club rides, and I commute on the club ride bike. It's all good.

For the last 5 years, I only had 1 bike - a 2009 Fuji Newest 1.0.
I put fenders on it and rode it to work 17 miles one way. Rain or
shine, summers and winters. about 2/3 years ago, I started
going on weekend club rides. Varying in distance from 40 -100
miles. Then I started doing charity rides; Five Boro Bike Tour(40 miles),
NYC Century(100 miles), NY Bike MS(100 miles), etc. All of this on the
same bike. I travel a bit and like to ride when I get to my destination.
So I made the decision to have at least 2 bikes. A new roadbike for long
club rides and century charity rides; and a folder for commuting and travelling.

http://www.youtube.com/watch?v=0slPl...6zPoymgKaIoDLA

http://www.youtube.com/watch?v=20LB8...6zPoymgKaIoDLA

I have a stable of bikes- my commuter ( aka my pick up truck- a hybrid with a milk crate in the back and a front rack where I can attach a basket, if need be); my "ice bike"/winter commuter (aka the tank- a MTB with studded tires and outfitted similarly to the above); my folder (aka the travel bike. This is the one I take to NYC on the train or when I am working out of town- even Europe) and then my road bike (aka the classic- a custom made steel framed bike from 1976 re outfitted with an updated Campy Groupo in 2001). The road bike is what I do almost all of my distance road ridng on with the exception of my dirt road bike ( aka the D2R2, which is an old Gary Fisher Super Caliber set up with a narrow profile slick tire for long distance dirt road riding).

I have several bikes for the task at hand, a daily commuter (e-bike, pedal assist) which gets the most miles (25 miles round trip) but is pedaled without the use of the motor 80% of the time. A sport oriented bike for riding fast, for fun rides and climbing hills. A fat bike for winter snow and trail riding, a full suspension bike for riding rough and technical terrain with my wife on her mountain bike.

I just ordered a road bike for my wife to ride the road and go on short trips and tours, and I am working on a custom touring bike to ride with her on short trips and tours, commutes, day trips with her. The e-bike is heavy and I dont want to use it when riding with her on short trips, tours, day trips.

Right now I have one bike that does both, a Giant hybrid that has taken me on many metric centuries and has been my commuter since September. Six months of riding in traffic in all kinds of weather, though, has convinced me to get a dedicated commuter. I want hub based brakes for all-weather riding, a dyno hub, and a step-through frame. My new bike should arrive in about a week. When it does, I'll restore my hybrid to its pre-fender days and use it for longer, faster recreational rides.

I just have one bike, a Giant upright city bike, that I use for everything. But I don't ride club rides or anything like that. These days I commute on it and use it for errands/transportation if my destination is within decent riding distance. I don't think there's anything wrong with having more than one bicycle, but in my personal circumstance it's not necessary.

I have a whole bunch of bikes, because I like working on bikes and riding different kinds, but even so I think it's a good idea to have more than one if you're going to commute - for an emergency backup if nothing else. I actually have multiple 'commuter' bikes, they're all set up for different uses (primary, winter weather bike, cargo hauler), but all are cheaper, less flashy bikes than the ones I typically reserve for recreational use*, that way I don't worry so much about theft or exposure to the weather when I lock them up in front of my workplace. Another difference is that I have racks and fenders on all my commuter bikes, but not on any of my recreational bikes.

*-of course there's some overlap, I use my 'commuters' for fun rides on a regular basis and once in a while I'll ride a 'fun' bike to work if I'm just going in for a short shift and am planning a longer ride afterwards.

I have a winter bike (alum frame, clip-on fenders) and a carbon summer bike. I started commuting to my current job in Oct so I've been using the winter bike. Once it dries out a little I'll switch to the carbon bike. Other than lights I don't have anything on my bikes specific to commuting. I carry clothes and anything else I need in a backpack. I might add a cross bike with proper fenders and disc brakes for next season.

I have my commuter, a converted Trek 7000 MTB, and my array of road bikes. While I've done the commute on the road bikes I'm much more comfortable on the commuter. I can ride the road bikes faster of course, in particular up the bridge, but in NYC traffic speed does not get you there any faster.

I have an array of accessories on the commuter, rack, dynamo lights, fenders, whereas all my road bikes are completely bare except for the water bottle.

Not really. I commute on my road race bike, my beater/utility bike, and my SSCX bike. Any one of those bikes will get me to work and back, so the choice of bikes really depends on other factors like whether I plan to do intervals at lunch, carry a lot of stuff, or don't feel like shifting.

I do occasionally commute on my other bikes, but I have a dedicated commuter. It's a Surly CrossCheck fixed gear with racks and fenders and lights, but nothing too high-end. I let the chain get all kinds of cruddy and dirty and worn before I replace anything, and I ride thick, heavy city tires on it. It doesn't need to be high performance, it just needs to be ready to go without my having to pay any attention to it. I also keep flat pedals with toeclips on it for use with street shoes. I occasionally commute as far as 20 mi each way on it, but don't really do longer rides than that on it.
My weekend/club/century/randonneuring bike is also a fixed gear, but for a bike I ride when I either want to keep up with fast people or am going to be on the bike for well over 24 hours at a time (I like long rides) I care much more about the little things being right. I keep everything cleaner and replace the chain when it wears out, and I have more expensive parts on it. I don't want to beat it up around town.
I have a touring bike, but it has gears and I prefer a fixed gear for a city bike... and it's still not a bike I'd want to beat up around town. I also have a geared road bike that I don't ride that often, but around town it would be a theft target. All three of these have clipless pedals too, which also makes them less convenient for just hopping on to get around town.
And my partner and I share a cargo bike, also with flat pedals, which is a tank that you'd only bother riding if you're actually hauling cargo. And while it does its job very well, it wouldn't be comfortable for the long haul, either.

I can't even keep track of how many bikes I have!

New bikes bring great joy.

No. I've ridden the same Campagnolo (currently 2010 Centaur Carbon Ultrashift 10 speed levers plus Record titanium derailleurs/brakes) equipped Litespeed on all my road rides since 1997.

With about $20K to spend on two bikes you can do that without compromises. Otherwise you're giving up something on the bike you ride on weekdays or the one you ride on weekends.

As a mechanical shifting aluminum rim riding retro-grouch the price point is lower but still non-trivial.

The market selling people criterium racing bikes (40.5cm chain stays, no eyelets, some without clearance for even 25mm tires) and now trying for multiples (you need an endurance bike, and a gravel grinder, and...) does make this harder than it needs to be.

Yes. Hybrid for commuting, road bike for weekend fun.

I have 1 dedicated good weather commuter, 2 winter commuters and 6 others. I have a touring bike, a 1/2 fat bike for snow and 3 mountain bikes I ride on the weekends. Plus a tandem. I find it much easier to have my bikes set up for commuting. I Like having fenders, mirrors , racks and bags on them.

My current primary commuter (spring, summer, fall) is a Kona Sutra touring/road bike but I only got that in the fall of last year; prior to that, I had urbanized my KHS Tempe 29er with narrower, slicker tires, racks, panniers, lights and fenders. On the 29er, I rode two metric centuries (back to back) and did it fine but this year, I'm going to use my Kona or my old Bianchi road bike (that needs more tuning). My 29er has been returned to its MTB form with knobby tires, seatpost rack, no fenders or lights. For next year's winter commutes, I'll be using my old Norco Bigfoot MTB that has racks, lights, fenders and I'm just making some DIY studded tires (both wheels need spoke work so this bike wasn't used this winter).

I have a low-end road bike with some upgrades that I've put most of my commuting miles on and have also used for triathlons and other events. It's almost 10 years old now. I suppose if I ever got really serious about triathlons I'd get a higher end bike for them and not use it for commuting except for maybe once in awhile.

I also have a winter bike since my road bike doesn't have enough clearance for tires I'd be comfortable using on ice and snow. And finally last summer (mostly on a whim), I salvaged my son's crashed 80's era road bike and converted it to a fixie. That became my main commuter bike so I'm not quite sure going forward what I'll end up using most often for commuting.

To your question, I don't think there's any particular reason you need a second bike for commuting unless your current bike falls short for that purpose in some way.

I have a 10 mile commute, and I rotate through 3 of my 4 bikes:
Rivendell tourer -- good when I have to carry stuff and want to go fast
Giordana racer -- good when I don't have to carry much stuff and want to go real fast
Schwinn MTB townie -- good when I have to carry stuff and don't care about going fast

My Cannondale MTB isn't a fun commuter, but it rocks on MTB trails.

Same here for my 14 mile one-way commute, on a Specialized S-Works on the bumpy streets of Boston. I did put it away in December, not to emerge until April at the latest. My other bike is a Cannondale Mountain bike for all my winter riding, and as a beater for rainiy days during Spring through Fall. I did consider a lower grade road bike for dry winter riding, but the Cannondale is fine.

I used to have one do-it-all bike for my 21 mile, one-way commute. It was a Specialized Secteur Triple with Sora 8sp components.
I'd take the rack off for weekend rides, but that was becoming a PITA.

When I changed my commute, and started taking the commuter train between Dallas and Fort Worth, I decided to change bikes as well.
I stripped the Secteur and put the 8sp drivetrain on to a Windsor Tourist frame. Then I put a nice 10sp road setup on the Secteur.
Now the Tourist is the commuter bike, and the Secteur is the weekend fun bike.

Then there is the single speed....

I have a 40 mile commute that I do a 2-3 times a week whenever the temps are above 20F. For a couple years I owned only one bike for commutes, group rides, and tours: a Fuji Absolute 3.0 hybrid. It came with an adjustable threadless stem that gave me a wide range of riding positions depending on what type of ride I wished to do, and an easy swap out of tire widths/treads gave me even more versatility. Last summer I purchased a nice road bike for group rides, and made my old hybrid into a dedicated commuter/touring bike. I replaced the flat bars with a nice northroad style and Brooks saddle to make it even more comfortable for long rides. I enjoy having these options, but truly it depends on your budget whether or not you can justify having more than one machine. For me having the proper tool for the job is important for my enjoyment of the sport. (Not to mention the fuel savings of my commutes come out to roughly $6 a trip, so I feel more than justified in indulging my passion.)