Hello,
I've recently started biking regularly, about a month and a half ago.
Before, I was only biking on weekends on my hybrid and a bike that I bought on amazon that just looked like a road bike.
Since riding on regular basis, as a beginner, I didn't do anything significant; riding about 4 times a week, 20miles, avg of about 17mpg.
No considerable climbs(in Chicago) just stop and go type of riding.
I felt very comfortable doing the type of riding that I was doing and it was getting easier and easier, given how I felt after the rides, that I wanted to extend my rides by about 5~10miles per ride.
All of a sudden, about a week ago, I started having fatigue in the middle of the rides, usually at around 5miles into the ride and I have extremely hard time finishing even 20mile rides I was doing. Completely out of breath, thighs burning.
I can't seem to push harder in segments I was doing well due to the fatigue and I'm barely finishing the ride, let alone extending the distance.
Has anyone experienced something like this in their beginning days? How do I get over this? Its so sudden and too strange I have hard time thinking its just muscle fatigue build over a month or so. Thanks for your tip in advance.

You don't mention your age, as a 20 year old this would be disturbing, as a 50 year old this would be aging, muscles don't just take up new activities, they require time to adapt, as does the "body", so if you're over 50 and this happened, it's just nature talking, if you're 22 better go see a Doctor, or see a bike shop for a proper setup of position.

Time to see a physician, even if it ends up being nothing. "All of a sudden" should warrant a visit.

If you haven't had a good blood work-up done lately, I would do as suggested above. Might not be anything but **********?

perhaps, like many, you suddenly just got tired of all this s#1t. it happens...

I'm 33 and in fairly good shape.
6' 155lbs. Play basketball and other sports regularly, nothing extraordinary buy well in shape.

Not even close... I've given serious thought abouy biking for about 2 years now, going through different bikes and trying out different things before committing to it. I get urges to run out of my office in the middle of the day so I can bike everyday lol

Must be that gallon of whatever you're drinking...

I had the same thing happen to me when I first started cycling. I was overweight (still am) and on meds for BP and cholesterol. I was doing great. 15-20 miles during the week and 30-40 on weekends. Then, like a switch was flipped, I felt like all my strength left my legs. The guys that I would have to wait on were suddenly waiting on me. Turns out it was the statin cholesterol meds. I could skip it one day and I was back. Take it again and no strength. I talked it over with my doctor and switched to a prescription fish oil tablet.

One reason to see a physician. Another cause would be BP that is getting lower with increased exercise in someone on meds for high BP (that was me). There's a million other things this probably isn't, but that I'd want to not have.

Checking with your doctor is never a bad idea when new unexplained symptoms come up. In the mean time, try taking a couple days off the bike and keep your activity at a recovery level. Get plenty of sleep. Eat well and stay hydrated. You might just need a break, could be you are fighting off a bug, voodoo curse, etc. If rest and proper nutrition don't put you back on your feet in a couple of days, then definitely check with your doc.

To be honest, you probably added to much too son.

I reckon if you add 5 miles to the total every couple of weeks and / or do some slower rides that allow your body to recover, you'd be better off.

You do have to build fitness AND allow the body to recover after effort, otherwise, you will get fatigued and / or become ill.

Keep it up, but perhaps only take smaller steps until you are comfortable at each juncture.

cheers

I recommend a new bike to harness the placebo energy. Preferably in red.

Looks like I'll have to take a few days off and see how it goes. Thanks everyone
The new bike is a month and a half old. In red. Lol. It's a 2012 trek 2.3 The placebo effect must be wearing off sooner than later

You can overtrain, not have enough rest time, that could be the issue. It could be a medical issue, too, had a checkup lately?

I assume you've ruled out bike factors like brake pads rubbing, seat post slipping (this happened to me), underinflated tires, riding at too low a cadence, stronger winds...

Too many hard days in a row without time to recover?

All of the above.

+1 you need recovery time.

Have you checked to make sure your brakes aren't locked onto your wheel?

That was my first thought, too. I've seen it happen to friends on group rides. Two people had slow punctures and one guy had his brakes stuck on the rear wheel.

Rule number 5 applies here...

^^this^^

did the temperatures change? heat exhaustion might have been an issue. I find the heat can affect my performance and I have to tolerate slower avrg speeds.

... wait, what rule #5 ?

This one?
https://www.velominati.com/the-rules/

Can't believe no one's said it yet: Nutrition. It sounds like you are bonking hard. Eat more of the right stuff at the right time. Bring food with you, granola bars, bananas, and lots of water. See if it makes a difference.