gregf83 

Faster in the summer than winter
Faster after a day off the bike with fresh legs
Slower on Fri at the end of the week. My legs are usually getting tired on Fri and I ride with a group on Sat
Slower if my legs are getting sore
Faster in a tailwind (not sure why but I can't relax with a tailwind and end up pushing hard)
I have a 30 min stretch of highway that I'll sometimes use for a long interval and a 3-4min bridge climb. I usually go fairly hard on the bridge (threshold to VO2Max for those familiar w/power)
Think I'll relax today...

ThermionicScott 

+1.

kickstart

My commute pace is my normal pace, relaxed.
Being a hilly area, and riding slow, heavy bikes, my actual recorded average speed is around 13 mph. My normal speed on the flat is around 15 mph, and hills 5 to 25 mph.
I'm not interested in performance riding, and the roads I commute on are all 35 mph or higher, theres no possible way I can go fast enough to satisfy impatient drivers.....even if traffic congestion has speeds down to my level....so I don't bother trying.

Steely Dan

when my one-way commute distance was 15 miles, i rode quite hard and aggressively for speed.

now that my one-way commute distance is only a paltry 5 miles, i ride more chill and relaxed.

FBinNY 

I might ride at a relaxed pace or push a bit depending on my mood, or how I feel that day. For some reason, my road bike "wants" me to ride harder, so I tend to push more when I take the road bike to work than with my usual commuter.

Also, I tend to take it easy going to work, so I don't arrive sweaty, but on a nice day I'll make a real ride of it going home, riding faster or farther. It's not rare for me to take the 40 mile route going home on my 6 mile commute.

Ky_Rider

Usually slow and relaxed. I like to look around. I'll sometimes get off my bike and walk a big hill to give my legs a break. My commute is about 1.5 hours and we don't have showers at work. Every once and awhile I'll try to speed things up but it doesn't happen often. Lol. If I ride 5 days straight my legs are toast by the end of the work week.

hyhuu

My gene only allows me to operate at two speeds: slow and slower.

ki4bbl

I think a relaxed pace for me...12-15 mph at a cadence of 82-86. My commute is 6 miles each way, so it is pretty easy. It's all flat, too. I get caught up on my books.

bigredkevbot

I also do not have shower facilites at work, so an intense-paced commute leads to a rather stinky employee. Additionally, living in the Boston-Metro area, it's best to be safer and slower then fast and risk being injured. There are a number of unattentive drivers on my way into work, as well as other cyclists and pedestrians that potentially jeopardize commuter safety. Nonetheless, I usually average 10-13mph on my commute. If Im on my roadbike or fixed gear, its closer to 14-15 mph average.

Darth Lefty 

I ride up to the limited exercise capacity imposed by my health problems. This is usually about 8-11 mph average depending which direction and which bike. Depends a lot on where I am with my blood pressure meds, hydration, and blood sugar. For some reason if I eat over some threshold amount of carbs it really kills me for hours.

I used to do 16 average on my fastest road bike, but never got any faster than that. I blamed it then on my weight, but in hindsight probably also my health problems lurking.

bmthom.gis

I go at whatever pace I feel for that day, and it is never b alls to the walls on my commuter. That just makes me not want to ride the next day. I wouldn't be surprised if my bike and stuff weighed somewhere north of 35 lbs. It is what it is.
I also don't care if I annoy motorists. I have as much a right to the road as they do. 80% of my ride though has bike lanes.

12strings

I generally try to go easy on the way to work in the morning, primarily to avoid sweating too much. (7.5 miles in 40 minutes = avg 11 mph)

On the way home, I can push it more, since I know I'll just shower when i get home. (7.5 miles in 30 minutes = avg 14 mph)

The route is about the same eleveation both ways, with lots of small ups and downs, and one larger (1mile) hill up and down.

So still, I'm not going supper fast, though I probably get up to 20 or above on some flat parts...and about a mile of the trip is on a "chip and seal road", which really slows me down.

caloso

Most days of the week I have training rides that coincidentally begin at my house and end at work. On those days, I'm usually looking at power, not speed. And on days when I'm just riding to work and back, I'm not looking at my computer.

lostarchitect 

I am faster than most of the Citibikes and townies, and slower than most of the road bikes and fixies. I guess I proceed at a moderate pace.

rumrunn6

when I bike commuted I went as fast as possible in the morning and on the way home I just went at a pace that I could sustain for the distance. going in was mostly downhill so I went with it, you know? going home was mostly uphill so I worked the climbs. I suspect that if the ride had been an equal elevation gain/loss each way, then I would still charge out of the gates in the morning, cuz that's just how I am.

Booger1

I'm old and worn out.....Everything passes me...

spare_wheel

I'm extremely competitive on my commutes...I try to pass as many cars as I can.

grolby

Because I live nearby to work, I try to save the fast stuff for training and races. I am seldom interested in hammering because I wear street clothes and don't want to show up to work all sweaty and tired. I will be moving further away at some point in the coming months, at which point the requirements of comfort (i.e. wearing bike clothing) and the opportunity to get some training in on the commute might cause me to change my habits.

I can practically guarantee you that they can't and aren't maintaining 25mph unless they're referring to a slight downhill section of their commute.

caloso

q.f.t.

fietsbob

I played public library's Books on Tape into earbuds to fill the time when I had an hour long ride home..

mgw4jc

I'll push it a little on the flats/downs or with a favorable wind. But for the most part I'm just cruising. This interesting thread prompted me to look up my speeds which I have in Garmin Connect since I started tracking about a year ago:

2014 Avg Speed
Feb 16.6
Mar 17.0
Apr 17.4
May 17.4
Jun 16.0
Jul 16.8
Aug 16.3
Sep 16.3
Oct 16.8
Nov 16.5
Dec 16.2

2015
Jan 15.9

I'm not sure why the big drop from in June. And I've definitely been slower over the colder months (more gear I guess). It will be interesting to see if I trend back up or not without necessarily trying to.

Oregonroadruner

I don't have a computer so I don't know how fast I'm going but then I'm at the point now where I don't care. I go fast if I want to or slow if I need to. It depends on traffic and pedristrians.

mconlonx

I don't really pay attention to speed or average speed on my current commute, where the lockup bike has no computer and the whole commute is interrupted with a bus trip

When I was doing a 38mi r/t commute, I would average 13-16mph depending on the time of year. Early Spring, fresh out of winter? 13. Middle to end of summer? 16. But that particular commute had some hills and I was always faster heading in than coming home, so a 19 mi o/w to work avg would be something like 18mph, but 14mph on the way home on a good day when I was in shape.

And I'd consider that a moderate speed for me. I could sight-see all day long at 12mph, I think the fastest o/w to work time I ever logged was 20mph... peak season, running late...

Buffalo Buff

Yup, I'm not even 30 yet and my commute is only 3.5 miles. So I treat the entire thing as a sprint. The traffic light I have to go through half way acts as my rest. Plus I'm not very active at my job, mostly just standing around, so like the poster below I love trying to destroy my legs as best I can before I get into work.

I'm the same way. If I see ANYONE not in a car, I'm passing them. It's just something I do to push myself. Doesn't matter if I'm just commuting to work or half way through a weekend century, I have to pass haha. Never been passed back, and I think the day I am I'll be making a new riding buddy

WarrenR

I used to go faster and faster on my commutes untill I went over the handlebars twice, one passenger side door and one right turning vehicle with a burnt out right rear blinker. Then I slowed down to smell the the roses and found my commutes to be much more enjoyable.