Hmm, carrying a 12-14 lb load on your back for 72 minutes? I'd rather take an extra 10 minutes.

You might also consider how valuable those 10 minutes are after shedding "heavy" fenders if you ever have to commute in wet conditions.

Mine with standard loadout hovers around 45lbs w/o water, but when I'm packing equipment and water probably hits the high 50's.

Lots of folks carry around an extra 20 lbs or more all day and don't even notice. ;)

On my 30 minute commute I carry about 10 to 15 lbs in my backpack and am not bothered by it in the least. I'm not sure about 72 minutes but a 10 minute savings each way is significant.

I'm never too concerned about weight, but just for curiosities sake I did weigh my rig and my wife's the other day. When I weighed her commuter bike it was still loaded and came in at about 40lbs. I've not weighed the bike unloaded yet, but I figure she probably had about 10lbs of gear on there and it'll come out to just over 30lbs. It's got pretty thick aluminium tubing.
My steel framed Miyata weighs in at 26lbs, unloaded, with the front rack removed (I don't have panniers small enough for the front yet).
My old commuter machine, a 1980 Sekine with the chromed-steel rims is about 30lbs unloaded, and I used to haul around about 20lbs or so of gear on there every day.
I think with good maintenance and nice tires that 50lbs is really no big deal once you get rolling... Although I suppose you might notice the difference if you have a lot of hills on your commute.

I have both pack rat and weight weenie tendencies.

So I ride a basic 20 lb road bike and carry a backpack that has at least 2 lbs of stuff in it that has no reason to be there.

I am a little surprised at some of the advice. Personally I HAVE had 2 flats in one ride and was thankful to have both a spare tube and a patch kit. Not only that I was able to help somebody else out a couple a weeks ago who had a flat. I happened to have an extra (partially used) patch kit on my bike and just gave it to them. It's not like those things weigh a ton anyway.

It's also worth it to me to carry a lock vs leaving it at the office. What if I need to stop somewhere between home and work?

The bottom line is that if you're not bothered by 50 lbs worth of bike and accessories then that's all that matters. It's your commute. If it's 100+ degrees outside and you feel it's wise to carry a couple extra bottles of water then do so. To me there's a certain convenience and fun involved in having a light rig but it's an entirely personal choice.

I don't stress too much about my main commuter's weight...it has racks, fenders, sprung Brooks and lighting...of course it isn't light. I didn't chose the lightest parts either. It can be a little annoying taking up and down stairs, but riding is smooth and it has nice easy gearing to compensate.

http://i936.photobucket.com/albums/a...lk67/photo.jpg

I use this with my wife for errands, fun and whatnot...the weight and bulk make it a pain to move, and it flexes a bit...but it rides nice and smooth with a sensible gear ratio.

http://i936.photobucket.com/albums/a...7/IMG_0657.jpg

i ride with water bottle, spare tube and tools. I keep clothes at work and change them on weekends or when not riding.

My summer commuter bike weighs 15 pounds with pedals. Full carbon road bike with a Record drivetrain & carbon tubular wheels. I have a 40 minute commute each way, with restrooms and water enroute. So I don't even have water bottle cages. I carry a spare tubular tire and a mini pump, essentials tool kit and a cell phone in a small backpack. In the last 10 years I have only had to use the cell phone once to hail a cab, when my spare tire proved to be faulty.

My winter bike is a steel-framed flat-bar custom with an Alfine hub, Vittoria Randonneur clincher tires and enough lights on the bar to cast shadows a block away. I'd guess it weighs close to 30 pounds. 700c wheels of course. Riding on either pavement or smooth gravel, there is no point in suspension that drains pedaling energy due to suspension bob, and also adds lots of useless weight. Riding suspension forks in the rain will also cause them to eventually fill up with water which will turn them into a corroded, seized mess.

Switching from the summer to winter bike is wretched misery. If you haven't ridden a 15 pound bike, you may not want to. It is is a life-altering experience that will spoil your tastes forever.

The shop is right.

I'm on the end of the spectrum not bothered about weight (flat commute), I would rather have what I need for repairs etc...
My commute bike is 50 to 65 lbs loaded, depending on whether I carry my laptop, and how much food I bring for lunch that day.
I use panniers, not a backpack, it's easier for me.
I did a 500 mile bike camping trip once at 90 lbs total (not including my body weight), yes it's slower, but really, so what?
On my commute, I'm looking to do more work, not less, so it's a good trade off for me.
For weekend fun, I also have a 22 lb road bike. Fun yes, but it's easier to break something or flat, so I've never used it for commuting.
To each their own...

23.4 lbs unladen

I have no plans to switch to the road bike for day to day commuting - the convenience of being able to carry everything I want and need, and the relative comfort of the commuter more than make up for the extra time. However, it is nice to know that I can shave significant time when necessary.

I hardly notice the weight of the backpack - perhaps because I used to carry well in excess of 35 on a moderately regular basis -- but it interferes with my rear view in my mirror, so I avoid it for that reason.