Over the last three years, I’ve regularly commuted by bike - thirteen kilometers each way pre-pandemic, now I’m down to five each - and until recently, it’s gone smoothly. To my surprise (especially since I have no stamina running) I didn’t much mind the thirteen km on my heavy three-gear commuter bike and didn’t even blink at the five.

And then I got my saddle, which was way too low, adjusted at my LBS one or two weeks ago, and ever since, I suck. I don't feel like there's much of a difference in how I'm pedaling, my speed is about the same or even slightly better, but the spikes in heart rate and feeling of pressure on my chest that make me a terrible runner come sneaking up on me on a sustained but not all that heavy climb. I don’t think it’s anything serious - I’m in my mid-twenties, don’t smoke, and heart disease doesn’t run in the family - but I do wonder why my stamina tanked so hard and how I get it back. Is it just that I’m using different muscles/using my muscles differently now and need to get used to it?

  • Do you pedal almost all the time, at least between forced stops like traffic lights or stop signs? You can't stop your effort when running without stopping, which isn't true on a bike. When you do your 5 km ride, do you pedal the entire way without ever stopping your pedaling? If you're in good condition, pedaling without stopping for a mere 5 kms is easy - even 13 km is downright easy too. If you pedal a few strokes and then coast, you weren't in as good a condition as you thought you were. If you do pedal most of the time, something else is going on, so it's important to know. Commented Feb 14, 2022 at 9:54
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    Not being able to run well indicates the condition is not that good. Most cyclists can run because of good aerobic condition. They just cant walk for 4 days afterwards because of the unfamiliar muscular load and 'impact'
    – Andy P
    Commented Feb 14, 2022 at 9:58
  • @Andrew Henle: I feel like I’m pedaling most of the way save for a short downhill stretch where I can’t, but I may well be overestimating myself :P Commented Feb 14, 2022 at 10:06
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    Did anything else change on your bike at the same time? I've occasionally found surprise brake rub that feels like I'm riding into a headwind. And it was caused by accident, a wheel refit after a tube swap, etc. Just check your bike is running fine before blaming yourself.
    – Criggie
    Commented Feb 14, 2022 at 10:10
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    @Criggie - I did change my brake pads, but actually asked the mechanic to take a quick look since that was the first time I'd mucked with them myself and they were fine. Doesn't really feel like more resistance from brake rub either, the only thing that feels different is my heart rate/breathing Commented Feb 14, 2022 at 10:31

2 Answers 2


A change of saddle height won't change your stamina. 'Stamina' is a crude term that reflects many processes within the body which contribute to powering the bike forward.
At a very basic level, we breathe oxygen which is used to turn stored fat/carbohydrate into pressing power on the pedals.

Most likely what you are seeing is the combination of the following 3 effects.

  1. Correct saddle height is allowing you to use more muscle mass which demands more oxygen, this would also explain your slightly higher speed.
  2. Your body will need to learn to adapt - until you get more practice you will simply be less efficient at pedalling
  3. Five km each way is very short for a bike journey - it's likely you are simply less fit than you were when you were doing a longer trip
  • The first point pretty much describes how it feels, anyway - I'm doing what feels like the same thing, but feel like I need more oxygen. Will try and keep an eye on what my heart rate etc. are doing over the next time and get more excercise in once that's started to settle. Commented Feb 14, 2022 at 13:18
  • It's not the case here, but "stamina" could refer to muscle fatigue, and thatcan be affected by riding posture. Certainly if I ride with a too-low (by more than about 3cm) saddle my quads start to burn far sooner than they should, and my stroke becomes less efficient
    – Chris H
    Commented Feb 14, 2022 at 14:05
  • Interesting observation. I've used a high saddle height (so I can almost stretch my legs) and find a low saddle height (for example on a borrowed bike) to be quite exhausting. You're saying that switching to a high from a low saddle height (so normally only cycling with bendy legs) would also cause someone to get exhausted?
    – MiG
    Commented Feb 14, 2022 at 14:08
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    @MiG I find that, but I do a lot of miles on a tourer with a saddle set appropriately high, and I have long thighs which might not help. I know I'm weak in deep squats/leg presses. The inefficient stroke was particularly obvious when trying to learn to ride a unicycle with a too-low saddle. I could only get power for a smaller than normal fraction of the stroke, and flexing my legs while maintaining contact with flat pedals clearly acted as a brake
    – Chris H
    Commented Feb 14, 2022 at 15:28

How’s the overall seating position? Increasing saddle height – without changing handlebar position – will lead to a more “aggressive” position which puts more weight on your arms and allows less room to breathe in your belly.

If your seating position was already fairly aggressive before the saddle height correction this could explain your breathing difficulties and elevated heart rate.

Has your speed increased? A more aggressive position can lead to people going faster because pushing down with your legs makes it easier to hold the position.

Has your cadence increased? Proper seating position makes it easier to ride a higher cadence. High cadence is usually less exhausting for the muscles but can tax the cardiovascular system slightly more.

Last but not least: Your body needs time to adapt to seating position changes. Which is one of the reasons why finding a good/perfect position is so tricky. Conversely, after some time the worst seating position can feel okay and any deviation will often feel awkward or can lead to strange muscle soreness.

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