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Whenever I near yellow or red lights, I slow down and pedal backwards as I coast so that I can continue to get exercise while I wait for the light to turn green before I reach the intersection. (It's a mountain bike; it doesn't have a coaster brake.)

Is this bad? From what I've read, crank-arms are supposed to tighten themselves as you pedal, so does that mean pedaling backwards loosens it? 🤔


(The only thing I can find when doing a web-search on this is about whether it's physically beneficial to pedal backwards on a recumbent bike, not about the effects on a bicycle.)



Note: Some people have mentioned that it's not exercise because of the low resistance, but that's like saying that a motor with no load doesn't burn any fuel or battery to turn. It may not be a hard exercise, but it's still movement. Moreover, there is another point to coasting toward the intersection in that coming to a complete stop at the light requires a lot of exertion to get back up to speed and it's very frustrating to feel rushed, trying to get across while cars wait. By coasting, I'm able to much more easily get through the intersection quickly once the light turns green.

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    There is a slight danger that you will cause the chain to jump off the cogs.
    – Daniel R Hicks
    Oct 5, 2020 at 0:51
  • @DanielRHicks agreed - more-so in a big-big gearing combination.
    – Criggie ♦
    Oct 5, 2020 at 3:49
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    @syntech you'd get more benefit by coasting normally to the red, and then doing a power-sprint when the light changes to green. The coasting moment is a brief rest where your muscles can prepare for the upcoming effort. This is also known as Red-Green intervals, and is a somewhat useful way to get some benefit out of your commute.
    – Criggie ♦
    Oct 5, 2020 at 3:51
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    @Criggie: There's also a slight danger of throwing off the chain when in biggie-big but as far as I'm concerned when arriving at traffic lights I always try to get into an easier starting while at the same time moving the left clipped-in foot to the 10 o'clock position. Most of the time I do this by a slowly stopping motion. (another reason for not turning the cranks backwards is that in early years I had been riding a German bike with a back-pedalling brake that could come to a nasty stop.)
    – Carel
    Oct 5, 2020 at 17:56
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    Coming up to a traffic stop it's more important to downshift to an appropriate gear, so you can start off quickly.
    – Daniel R Hicks
    Oct 12, 2020 at 23:27

6 Answers 6

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There are a couple of things you should consider:

  1. Your bike isn't going to care. You aren't going to loosen pedals or cranks spinning in reverse, because you're not applying any load, so there is no force in which to cause precession or fretting.

  2. You are getting no benefit (health-wise) from doing so. It might be better not to even bother.

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    "you are getting no benefit from doing so. Don't even bother." Why so broad and definitive? What if the OP has fun doing it? Isn't that a benefit? Or a perceived/imagined improvement of fitness? Perhaps it's better to specify that there's no benefit in a specific area?
    – Saaru Lindestøkke
    Oct 5, 2020 at 9:02
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    My muscles feel better when I pedal backwards after an extended period of a heavy load. I explain it myself with an improved blood flow but I never bothered to check for a more authoritative explaination.
    – fraxinus
    Oct 5, 2020 at 10:43
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    @fraxinus is right: moving your muscles without load has a very noticeable effect. I often did this by simply moving the cranks back and forth very fast but not very far (IGH with coaster brake). This basically loads the muscles with nutrients and oxygen, ready for a sharp, hard acceleration burst when the lights turn green. However, as nice it is to shoot away from the lights like this, I doubt that it has any training and/or health effects.
    – cmaster - reinstate monica
    Oct 5, 2020 at 12:28
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    @SaaruLindestøkke: if the OP does it because it's fun, then they would have written so. Instead, they wrote "continue to get exercise". They're not going to get any meaningful exercise benefit, it's pointless
    – whatsisname
    Oct 5, 2020 at 15:56
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    I'd like to add that it just feels fun to pedal backward when coasting, regardless if there are any benefits, or not.
    – Thomas
    Oct 6, 2020 at 10:33
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No, pedalling backwards is not bad for the bike, or any of it's components in the situation you describe (an urban environment).

I base this on my own experience riding various bikes (with derailleurs, with internally geared hub) in an urban environment.

As noted in the comments on the question and answers:

  • it ever so slightly increases the chance that your chain will jump of the chainrings, but in my experience you can catch this happening just in time and start pedalling forward to prevent the chain from dropping.
  • don't shift gears just before pedalling backwards as that will very likely lead to your chain dropping or getting stuck
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    (+1) but worth noting that you should be careful not to shift gears before pedaling backwards, as your chain will almost certainly skip then
    – Cliff AB
    Oct 7, 2020 at 0:01
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There is one benefit to you as a rider, to continue your pedal stroke while coasting.

You look like a bike which makes you safer.

I've noticed especially in ebikes that are being ridden like motorcycles, that a lack of leg motion makes the whole bike/rider combo look more static than it is.

So by continuing to revolve the crank with minimal effort, you look more like a moving object on the roadway and less like a static item, thus you're more likely to be seen by motorists.

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    Whether it is good idea to look moving at stop light/sign is very different question :)
    – Alexei Levenkov
    Oct 5, 2020 at 21:06
  • @AlexeiLevenkov erm we might be at cross purposes - OP said he slows down and coasts up to a red light while backpedalling. This answer was one positive about turning the cranks while coasting, because there's no training/exercise benefit. Once you're at the red light then stop with a foot on the ground and wait for the green. I didn't mean to keep pedalling while at the red light, just on the approach.
    – Criggie ♦
    Oct 5, 2020 at 22:06
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    I don't think this really addresses the question, because the OP could pedal in either direction to maintain leg motion.
    – user3067860
    Oct 6, 2020 at 14:07
  • @user3067860 true - my point is "you look more like a bike" which is of benefit to being seen. But you're right its not going to damage the bike significantly.
    – Criggie ♦
    Oct 6, 2020 at 21:06
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    Not sure this is makes a significant effect on your safety, but I sure sounds convincing. +1
    – Karl
    Oct 7, 2020 at 18:56
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I always used to pedal backwards on corners. Once when abroad I hired a bike with a coaster brake. Therefore nearly killed myself on the first corner and trained myself out of that habit rather quickly. So possibly bad for the bike if it ends up crushed at the same time as you. I would recommend losing the habit.

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  • Knowing myself and my habits, I'm sure I would have discovered the coaster-brake long before actually hitting the road. 😀
    – Synetech
    Oct 7, 2020 at 16:29
  • Good point; coaster brakes are horrible. But as long as you just stay away from those, there's nothing bad about a habit of back-pedalling.
    – leftaroundabout
    Oct 8, 2020 at 9:17
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Some bicycle components do have left hand threads. The left pedal and the left cup of BSA threaded bottom brackets are left hand threaded, because otherwise, they may unscrew as you pedal.

When you reverse pedal, you would only be producing minimal power. You would only have the internal resistance of the chain and freewheel to overcome. Thus, I suppose that if you pedaled in reverse for a very long time at your maximum power, you might eventually unscrew your left pedal and possibly your left BB cup (if you have a BSA BB). That seems like the only possible downside to reverse pedaling. If your components are torqued properly, I wouldn't expect this to happen at all. You would have to reverse pedal far more than people in normal cycling, at the very least.

However, you also aren’t really getting any exercise from pedaling in reverse, because you aren’t pedaling against any meaningful resistance.

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    Pedaling backwards is unlikely to produce enough force through the drivetrain to overcome the static friction limit, which would be a prerequisite for the threads unscrewing.
    – RLH
    Oct 5, 2020 at 16:57
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    Or the components haven't been properly torqued first place.
    – Carel
    Oct 5, 2020 at 18:02
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    My wife did this on a static exercise bike: cycle X minutes forward, then X minutes backward. By the time I realised what she was doing, she'd been alternately loosening and tightening the left pedal so much she'd destroyed the thread on it.
    – Kaz
    Oct 6, 2020 at 14:09
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    @Kaz: That's very different from the OP's bicycle, though, because there was actual load while pedaling backwards, right? No freewheel, just fixed transmission between the friction load and the pedals, is normal for stationary bikes. Still an interesting data point, but I think RLH's point about not overcoming static friction still stands for a freewheel bicycle.
    – Peter Cordes
    Oct 7, 2020 at 4:39
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    According to the above link, the reason for the righ/left-thread on pedals is not direct torque (which is negligible) but "mechanical precession", i.e. the circular working force/movement caused by the pedal load (not the torque). That said, going against the main direction under load (e.g., standing up) could over time loosen the pedals. But since it's only while approaching a light, and presumably not while standing, it doesn't matter.
    – Peter - Reinstate Monica
    Oct 7, 2020 at 12:45
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It depends on the type of bike you have. And like RLH said also by how it was designed threadwise.

It is risky of the chain coming off. If you have a kids type bike the brakes are often operated by pedaling backwards but you cant go very far that way.

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    I wouldn't call IGHs like the SRAM 7-speed a "kids type bike". I've ridden twice around the world with such a setup, and would not want to swap it for a chain-shift bike for any price. (I did swap it for a Rohloff, though, which does not include a coaster brake because of the way its lubricated.)
    – cmaster - reinstate monica
    Oct 6, 2020 at 7:18
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    Since the OP said they already pedal backwards, it's pretty safe to assume that they doesn't have a coaster brake.
    – whatsisname
    Oct 6, 2020 at 14:16

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