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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.

Synetech
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    There is a slight danger that you will cause the chain to jump off the cogs. – Daniel R Hicks Oct 05 '20 at 00:51
  • @DanielRHicks agreed - more-so in a big-big gearing combination. – Criggie Oct 05 '20 at 03:49
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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 05 '20 at 03:51
  • Any decent mountain bike should be able to handle this pretty well, especially trail and enduro bikes. This is because pedaling backwards can become a tool for more experienced riders. Doing a fakie (riding backwards) requires backwards pedaling. You also must re-adjust your pedals often when doing freeride, which means pedaling backwards a bit. I've never heard of problems arising from pedaling backwards. Worse comes to worst, you can always just tighten your cranks. – LemmyX Oct 05 '20 at 17:17
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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 05 '20 at 17:56
  • Some (older) bikes have a coaster brake that required you to pedal backwards to activate it: https://sheldonbrown.com/coaster-brakes.html – Kaz Oct 06 '20 at 14:11
  • I remember when I was younger, I once decided to try pedalling backwards quite fast while the bike was going on momentum alone, just for fun. Completely twisted the derailleur hanger, it took a good hour with the pliers to put it back into shape. Still don't know how I managed to do that. Had this bike for some 12+ years and that was the only major repair I had to do. It may be anecdotal, but the fact is I never dared to pedal backwards 'for fun' since then – crizzis Oct 06 '20 at 19:14
  • It's not an exercise to pedal backwards against a freewheel. :-D OK, a coordination exercise perhaps. But if you want a challenge there try ropeskipping backwards. – Karl Oct 07 '20 at 18:53
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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 '20 at 23:27

6 Answers6

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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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whatsisname
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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 05 '20 at 09:02
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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 05 '20 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 05 '20 at 12:28
  • @cmaster-reinstatemonica do you have a more scientific explanation for "loads the muscles with nutrients and oxygen" ? – stijn Oct 05 '20 at 14:18
  • @stijn If you are asking for a paper, no. My comment was simply the combination of logic (moving your muscles does increase blood flow, moving your muscles without loading them thus provides nutrients and oxygen without burning them away) and my experience (I can accelerate much harder after shaking my muscles like this). But I didn't do any scientific experiments to test this theory. – cmaster - reinstate monica Oct 05 '20 at 14:43
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    @cmaster-reinstatemonica I am also not sure about your own explanation, but it is accepted that soft pedaling at around 50% of your functional threshold power and high cadence is good for recovery after a hard effort. In the middle of an interval session, it does also keep the legs moving. The thing about 50% FTP is that without a power meter, you will easily exceed this even if you think you're pedaling easy. It is actually hard for me to be on the road and moving at 50% FTP, even looking at the power meter! – Weiwen Ng Oct 05 '20 at 15:17
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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 05 '20 at 15:56
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    @whatsisname Sure, I agree they're not getting any exercise benefit (although other commenters disagree), but that's not what your answer says. It just says "no benefit". The additional "Don't even bother." makes it sound (to me) very universal and definitive (as mentioned before), so that's why I suggested a specification of the lack of benefit. Perhaps "You are getting no fitness benefit..." or "performance benefit"" would fit your message? – Saaru Lindestøkke Oct 05 '20 at 16:03
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    @cmaster-reinstatemonica: You can as well go on pedalling forward but at a lower cadence. I refer to my back-pedalling or coaster brake comment above. – Carel Oct 05 '20 at 18:00
  • @Carel Not while waiting at a stop light. When standing, you can't pedal forward, and with a coaster brake, you can't pedal backwards. But you can rock your pedals. – cmaster - reinstate monica Oct 05 '20 at 18:23
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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 06 '20 at 10:33
  • There is load on the pedals if you're standing, and that's also the only way it can possibly be any exercise. – Kaz Oct 06 '20 at 15:03
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    @whatsisname recovering, stretching, improving the blood flow are things that can be part of a fitness exercise. – EarlGrey Oct 07 '20 at 15:59
  • Regarding benefit, it does benefit health-wise because any movement requires burning at least some calories to provide the energy. But more importantly, by avoiding coming to a complete stop at the intersection, it makes it much easier to get back up to speed. (I hate having to burn my legs to try to get up speed to cross the intersection while cars wait. It's so annoying when I wait for them to turn, but they wait for me so I have to try to rush across. ) – Synetech Oct 07 '20 at 16:26
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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
Saaru Lindestøkke
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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 07 '20 at 00:01
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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.

Criggie
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    Whether it is good idea to look moving at stop light/sign is very different question :) – Alexei Levenkov Oct 05 '20 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 05 '20 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 06 '20 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 06 '20 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 07 '20 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.

efelf
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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 07 '20 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 08 '20 at 09:17
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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.

Weiwen Ng
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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 05 '20 at 16:57
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    Or the components haven't been properly torqued first place. – Carel Oct 05 '20 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 06 '20 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 07 '20 at 04:39
  • funny -- if I picture the rotation of my right pedal relative to the crank arm I'm pretty sure it turns counter-clock-wise when I pedal forward; that is, the right pedal should have a "left-thread", while in actuality the left pedal does (to which the opposite consideration applies). What am I missing? [Edit: For an explanation, see https://www.cyclefront.com/why-the-left-pedal-on-a-bicycle-has-left-handed-threads/] – Peter - Reinstate Monica Oct 07 '20 at 12:39
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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 07 '20 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.

biker guy
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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 06 '20 at 07:18
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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 06 '20 at 14:16