Psimet2001 

There is something to the temp. I have known riders that really don't perform well unless it's hot. The hotter the better for them. Personally I always raced better in the spring and the fall. Early season races and then late races into cyclocross. I figured out after many years that 50's/60's are perfect for me.

It also mean that every year for Superweek in July that I'd be dying right when other riders were reaching peak fitness and enjoying the heat.

noodle soup

I get really slow below 60F, and the best temps are 70F-100F

Bob Ross

^^^This

Also: cocaine

CoogansBluff

I should've mentioned that as another possible explanation. Some stretches of my ride have been newly paved. That's a gift to bike riders.

adamhenry

Wind has a large affect on my cycling speed. On an out and back trip, I will be quick going downwind and equally slow coming back upwind.

wipekitty

Dewpoint and temperature, for sure. If the dewpoint gets around 70, my speed drops. Somewhere around 30-40 is nice, even if the actual temperature is warmer. I think there's also a certain headwind/tailwind speed that is ideal, but I'm not sure what that is.

Other times, it's just my mood: I get in a mood where I need to ride. My fastest ever solo effort was when I was super ticked off about something. I remember being cranky, getting in an anger flow, and really letting it rip.

nomadmax 

What suddenly makes me faster?
Taking all data logging devices, of any kind, off my handlebars.

What suddenly makes me slower?
Putting them back on and seeing the truth.

Andy Somnifac

I think that getting hit by a car would suddenly make you faster followed by a sudden deceleration.

rivers

On our first club ride after lockdown restrictions eased, myself and the two friends I was riding with managed to do our fastest lap (my club has a set Saturday morning route) by a long margin. Even though we had been riding together in our own little bubble once we were allowed to meet up with friends again, just the excitement of being out on a club ride carried us along.

scutchin

Proper nutrition.

I did a 40 mile and my body just failed, ate like crap for days before and only drank water.

A week later I did a 60 mile and felt great. Ate a good meal the night before, Nuun in the morning, Tailwind and Clif bars during the ride. Massive difference.

RGMN

I find I ride much, much slower when I'm actively having a heart attack than when I'm not.

oleg232000

I pretend there are zombies chasing me....HA

But personally, well inflated tires, cooler temps, and a well lubed/tuned drivetrain make a world of a difference for me.

burnthesheep

The CRR of rougher country roads on the TT bike are easily 1mph slower sometimes. The routes closer to home by the lake are hillier, so should be slower. But the avg speed isn't much lower due to much better pavement.

If you can hear the tires on the pavement whirrr....yeah, not quick. There's a single 1 mile long strip of new pavement on the country road near work I do TT workouts on. When I hit that fresh patch, it's sometimes a gear change depending what cadence I'm already at. The pavement change is a solid difference.

Another........ where the downhill parts lead seamlessly into the next uphill. The momentum saved there greatly influences the speed. As opposed to the cursed sharp corner or stop sign right at the bottom of a downhill and the subsequent slog uphill after stopping.

oldernwiser

So true. I had 2 Rottweilers come after me with fangs showing, before I even knew what a Rottweiler was, but I didn't stick around to see if they would actually bite.

oldernwiser

For me the temperature is not the reason, as my best record was set at 95 degree temperature. I attribute this to what I ate. I puposely tried something healthy that I grew. It seems to double my endurance, but in this case I noticed I did not feel the heat as well. Yes!!

Other factors that I noticed a difference:
Sleep -(huge) in that is giving your body a few days to recoupe, like running a marathon, don't expect to do something really hard after burning so many calories the day before. Example. I did a 40 mile round trip through an elevation gain of 4,000 feet to 8,000 feet above sea level. I thought it was not easy. I went across another mtn. pass, with a friend, a few months later, that the summit was 9300 feet above sea level. Basically it was 50 miles from my house to the summit and I burned 5,000 calories to get there, let alone coming home. The next Saturday , a week later, I tried the first summit that I mentioned that only went to 8,000 feet. It was like " a piece of cake". I couldn't believe how easy it was.
4 hrs sleep before a big race just doesn't cut it, it is not enough, as I discovered.
Now to mention a few other factors.
Nutrition
This includes hydration, cannot be over stressed. I use Dr. Guerrero's formula that triples your endurance in athletes. I passed this formula to a friend who runs 150 miles through Death Valley in June (crazy) temperatures even when running at night were not below 95 degrees. He reported to me that he really noticed a difference and it also helped him from getting delirious, like other Death Valley runs he had done before.
My daughter at 4 years old , rode her little 1 speed bicycle with 10 inch wheels ? about 13 miles? Amazed my wife and I, because the most she had done before was a few blocks around the house. I noticed later , that when we ate my homemade multi grain cereal she had lots of energy. When she had just eggs for breakfast all she wanted to do was go a few blocks and she was done.
Equipment ​​​​​​- I noticed at least a two mile an hour difference when I bought my new Fezzarri bike where I had to clip my feet into the pedals. My joy riding up hills also increased when I was able to use more and different muscles as I was able to crank on the upstroke as well as the normal downstroke. Besides being lighter, this made a huge and an immediate difference.

As you mentioned, Tire pressure makes some difference, also your attitude and energy before starting. Keeping a bike tuned up increases my joy in riding. I love a quiet well oiled machine, especially no squeeking. (Ha,ha) On that note, I have been running a new chain oil that is the best stuff on the market. Probably should make a separate post about it. (No chain noise, best lube I have ever used, applied once a year ago, no mess, no plastics, waxes, or silicone).

momoman

Heat definitely affects me. Above 85 degrees or so my heart rate jumps 10 bpm higher than normal over the same course and I’m riding at 85-90% of max heart rate instead of 75-80% or so. I don’t have as much energy to push harder and faster in higher temperatures and I don’t try since I was diagnosed with AFib years ago, but not on any medication. I’m surprised to hear some say they ride faster in the heat.

cyclebycle13

Getting your position dialed in so you're properly balanced on the bike. I've never experienced anything like it.

noodle soup

Using bad tires with stiff casings(like Gatorskins) will definitely slow you down. If thorn punctures are your main source of flats. tubeless is going to be smoother, and likely faster.

canklecat

Besides bike prep and conditioning, for me the biggest factors are wind and my health. I'm a tailwind mooch. With an auto-immune disorder and screwed up endocrine system, I can't handle hard efforts in heat anymore. And with a screwed up neck (busted up C1-C2) it's hard to hold an aero position for long.

My bikes haven't made much difference, other than the rare occasions when I've tried aero bars. My speeds are about the same whether it's on a 24 lb steel bike or sub-20 lb carbon fiber bike. We don't have enough long, serious climbs for the weight to matter. But if I can get and hold an aero tuck, I'll be faster.

Most of this summer my heart rate would hit 130 bpm just coasting downhill from my home to the nearest turnoff toward my favorite cycling route. My max HR is 173 and I'd come close to pegging on the first climb, regardless of effort.

But Saturday evening the autumn temperature was in the low 70s and I barely cracked 130 bpm on climbs and averaged 116 bpm on an easy paced ride. The same effort a month ago when the temp was over 100F, my HR would average 150-160.

With a lower heart rate I have a lot more overhead to push harder. That's confirmed looking at my data the past couple of years -- my fastest speeds/shortest times on the same routes are always in spring, autumn, and on rare occasions an unusually cool summer morning or evening. In summer I'm just treading water, not making any improvements.

I've discounted the strong wind effect that's common here in spring because my routes tend to be equally affected by headwinds and tailwinds. My fastest rides are usually in neutral wind conditions. On days with strong winds I may have some unusually fast segments with tailwinds and even crack a Strava top ten, but I'll be a slug on the return trip while the genuinely strong riders are holding their averages.

billyymc

Loose dogs make me faster. Sometimes not fast enough.

walnutz

Seeing a lot of people post here about higher tire pressure making faster. Can anyone explain this to me?

oldernwiser

for me, I don't notice much difference in 5 lbs , but when I am in a hurry to get to work and I am running at 80 lbs instead of 100+ then yes I definitely notice a difference. I used to run 120 for a bike race, because as the heat from rhe asphalt and the summer sun temperatures are hard on the rubber and the tires seem to deteriorate faster as the tire flexes more over irregularities in the surface of rhe road. I also seem to be less prone for getting a flat even from goat horn stickers. This last year for example I rode all year mostly on my commuter road bike without a single flat, then this last week I had 4 flats, only two of which were from goat heads go figure.
I run tires that are rated to 125 lbs, but I found that when I run them at 100+ they last longer. Two nights ago, one of my tires separated from the heat and pressure and blew a hole in tire and tube. To answer your question, look at car tires, the fat wide tired car gets less gas mileage because it takes more effort, but if you need more surface area for more friction, then wider is better. When I ride my mountain bike it seems I go half the speed with twice the effort over the 23C s or even 25c's that I am currently running on my road bike.
When I ride in rhe snow and ice during the winter for fresh snow and ice, to my surprise i prefer the 23c s because they cut through the snow and ice better especially steering is important and I always get into trouble when my front wheel starts sliding around like it does on the mountain bike after the tread picks up and holds onto the snow. (No steering snowball on snowball) I usually weigh about 185 lbs with my backpack loaded with gear and food and whatever I need for the day at work so tire pressure for that amount of weight is very important. Now when I ride in a race without a 30 lb backpack on especially going uphill, I feel light as a feather, so I can't tell you what difference 5 lbs make. When the snow is crunchy and lots of frozen car ruts I prefer the softer ride of a mountain bike tire.

My best suggestion is try it out for yourself and see what you think, and draw your own conclusions. Psychologically it will make a bigger difference than what a salesmans pitch will.

dmanthree

Lose weight.

Well, that and proper diet, and the usual exhaust, recover, repeat.

SVTNate

Carbon fiber everything. Adds horsepower to the bike, which is proven science.

I'm working on carbon fiber socks, patent pending. I figure they'll be worth 1.21 gigawatts over the course of an hour, allowing the rider to hit 88mph and travel back in time.

Also, I feel that, like others have mentioned, planning ahead a couple hours in the nutrition department makes a big difference. My endurance and energy are quite a bit better when I've properly hydrated, done the electrolyte thing, and had some carbs before a long ride.

And, of course, keeping fueled.

And the tailwind, obviously. Yeah.

But really, it's all down to carbon fiber.

2manybikes

Caffeine and proper hydration.