What happens when freewheels fail?

[John in CR]

The freewheel on my main bike has been freewheeling for somewhere between 5 and 10 thousand miles, so I'm starting to think about it's failure. When they fail do they ever just seize up, or do they always just end freewheeling in both directions? My pedals suddenly spinning forcefully at 50-60mph would obviously be pretty bad news for the backs of both of my legs, especially at such a low fixed gearing.

 

[spinningmagnets]

Good question...I never considered that before. Perhaps its worth adding a free-wheeling bottom bracket as extra insurance?

 

[mwkeefer]

90% of the freewheels which have failed on me do so in a non latching way as the damage is always broken pawls. In a few cases, they have shattered but that was ICE engines driving cheapo freewheels embedded in large sprockets.

-Mike

 

[aronde]

I'd be interested in this also. My freewheel at present won't work in the high gear - turning the pedals just makes a horrible ratchety type of noise and it wont engage the rear wheel. All the other sprockets are fine though so I have put off replacing the freewheel due to the time involved in getting the wheel off and back on again!

 

[adrian_sm]

I have had two types of freewheel failure, both non-fatal type experiences.

1) Get's stiff
- Freewheel mechanism starts getting stiff/sticky, and providing more drag when freewheeling
- it is noticable as it starts to wear out in this way
- first symptoms were when back pedalling the chain starts to get slack and hits the chainstay.
- remedy was to replace the whole thing.
- I tried to pull it apart and clean it up, which did improve it, but as this is my daily transport, I preffered the piece of mind of a new one for $30

2)Falling apart
- second failure was when the freewheel cogs started to disassemble themselves as the locking nut came un-done
- first symptoms were a wierd sound, then a slight dragging feeling from the chain
- final symptom was eithera) chain jammed between cog and dropout, (b) freewheel cogs spinning without providing torque to the wheel
- still able to motor home
- problem was that my "new" freewheel had been disassembled before, and the locking nut not done up tight enough. Easy enough fix.

 

[dumbass]

I've seen a few type of failures, 1) the ball bearings fail and get ground up and lock the paws in ether engaged or disengaged, 2) the spring ring brakes and the paws will not engage and 3) Hmm, i guess there isn't a #3......YET !!

Bob

 

[amberwolf]

I've only actually broken freewheels by breaking the pawls, so they freewheel both directions. Theoretically it could be possible for the pieces to align themselves in such a way as to bind causing seize-up, but it's never happened so far to me.

I have seen them sieze up from rust, but not when in-use. Even then, sufficient application of power (coasting downhill at sufficient speed, standing on the cranks to keep them from spinning, in the lower gears) frees up most of them, sometimes with a little WD40 or very light penetrating oil (like gun oil, etc.).

I have also failed to tighten one up after cleaning/lubing it, and had it unscrew itself over a few dozen miles, then the bearings fall out and all sorts of nasty things happened (starting with the chain jamming and getting worse from there--fortunately that was my pre-motor and heavy cargo bike days, so the crash wasn't as bad as it would be now).

I can imagine a number of other dramatic failure modes that may not even be possible, but which would be catastrophic to the freewheel and potentially a rider/motor/bike under the wrong circuimstances.

 

[John in CR]

90% of the freewheels which have failed on me do so in a non latching way as the damage is always broken pawls. In a few cases, they have shattered but that was ICE engines driving cheapo freewheels embedded in large sprockets.
-Mike

Shattered and then what?

I've been counting on the pawls just wearing down to nothing, and lack of engagement or at worst a grinding freewheeling with some friction, but not enough to break my legs or sever an achilles. I was just wondering what kind of failures people have seen. I'm not driving power through it other than a bit of pedal assist at launch, which should reduce the risk of a failure in a troublesome manner....he types with fingers crossed.

The failure I'm worried about is cruising along not pedaling, and without warning there is no freewheel so the pedals start flying. I don't think coming apart and chain jamming kind of stuff would be catastrophic on my long heavy and low bike. From the sound of failures instant flying pedals is unlikely, and in a spinning the pedals case it's likely to be gradual enough to get my feet out of the way...At least I hope.

Thanks for the inputs guys.

 

[johnrobholmes]

If the freewheel starts to seize, it will likely happen over a few seconds and not all at once. I have only had two freewheel failure modes. Skipping, and totally falling apart. Since your freewheel is seeing just freewheeling use and not loaded use, you will likely see skipping from the pawls wearing down.

 

[mwkeefer]

Failure mode of a freewheel is exactly that - it's failure to open freewheeling, no racheting.

This means your pedals stop working becuase there is no connection between the rear freewheel, it's basically become a crappy bearing now

I understand your concerns, I've thought of it on many occassions (bad images of my shins smashed up like on a moped).

-Mike

 

[John in CR]

...it's basically become a crappy bearing now ...

A crappy bearing result is a perfect failure as far as I'm concerned. I just don't want a suddenly non-freewheeling sprocket as a failure.

 

[D-Man]

Take it off and dip in in sae30 oil. Spin it around and then drain it. You can use wd40 to clean it first. Then dip it.

 

[veloman]

...it's basically become a crappy bearing now ...

A crappy bearing result is a perfect failure as far as I'm concerned. I just don't want a suddenly non-freewheeling sprocket as a failure.

I always imagined a horribly way to die would be strapped to a fixed gear bike and pulled up to like 60mph. I suppose if that ever happened, the best thing to do immediately would be to get as much weight off the rear wheel and try to lock your legs, skid the tire flat then you might make it out in one piece. Of course, if you aren't strapped to the pedals, then just get off the pedals asap.

 

[dogman dan]

I suppose if it was a common problem mopeds would have dissapeared long ago.

But you go faster that a moped, so you are right to contemplate it. I'd think that a regular program of removing a freewheel and lubing it every few thousand miles would make some sense. Perhaps the same interval as tire replacement? You could just buy freewheels at the same interval as tires, or every other tire.

On the bike, you can lube a freewheel by laying the bike on it's side, and applying oil to the axle, letting it run through the thing and out the other side. Messy of course.

 

[gwhy!]

90% of the freewheels which have failed on me do so in a non latching way as the damage is always broken pawls. In a few cases, they have shattered but that was ICE engines driving cheapo freewheels embedded in large sprockets.
-Mike

Shattered and then what?

I've been counting on the pawls just wearing down to nothing, and lack of engagement or at worst a grinding freewheeling with some friction, but not enough to break my legs or sever an achilles. I was just wondering what kind of failures people have seen. I'm not driving power through it other than a bit of pedal assist at launch, which should reduce the risk of a failure in a troublesome manner....he types with fingers crossed.

The failure I'm worried about is cruising along not pedaling, and without warning there is no freewheel so the pedals start flying. I don't think coming apart and chain jamming kind of stuff would be catastrophic on my long heavy and low bike. From the sound of failures instant flying pedals is unlikely, and in a spinning the pedals case it's likely to be gradual enough to get my feet out of the way...At least I hope.

Thanks for the inputs guys.

Here is my bit of experience about broken freewheels I have never heard of one failing locked, they normally just start missing the ratchet on takeup or in really bad cases they slip off the ratchet under load, when they shatter which can happen ( this is more common on the more expensive freewheels in a pure non powered bike) is the worst case senorio because its can be hit or miss where the chain goes it could lock up the backwheel just after kicking the peddle arms around the wrong way maybe once or twice ( dependent on the size of your front sprocket ) .

 

[John in CR]

My big motors require a good amount of space between the hub and the frame, so it would require the entire length of the chain wrapping around in that space, and even then I'm sure the AL part the freewheel screw onto would snap before the wheel could lock. Strong plug braking from cutting the wiring harness seems to be my worst case failure. Sure that could dump me off, but I've at least got a fighting chance. That's a lot better than getting whacked in the back of legs full force by 300 rpm pedals that yank me forward and down dragging my broken legs under the bike while continuing to get pummeled by the pedals. Somehow that seems even worse than Veloman's death by fixie.

It sounds like a strongly locked sprocket as a failure result has a low enough probability to not worry about it. It was something I thought about a few times so I decided to ask.

 

[John in CR]

Freewheels can seize instantly. http://endless-sphere.com/forums/viewtopic.php?f=28&t=25153&start=0

Finally, a reason forcing me to gear so I always add pedal assist. Just in case, I'll need to put 2 freewheels in series on all my bikes.

 

[MadRhino]

The failure that you link to, is with a misaligned and weak freewheel crank. You have better chances of being hit twice by the thunder, than seizing a rear freewheel on your bike. Failure will be disengaging, or dislocation at the worst, nothing that would force you to pedal 60mph.

But it's true that with our E-bikes, we are more likely to see the end of a freewheel. We usually don't pedal enough to wear the gear tooths, that mostly happen long before any freewheel wear. We are also freewheeling them much faster, that should call for better maintenance care.

 

[MadRhino]

Finally, a reason forcing me to gear so I always add pedal assist. Just in case, I'll need to put 2 freewheels in series on all my bikes.

That may be a reason for you, but without that particular reason it's still a wonderfull feature. My next build will be with a Schlumpf HS drive, to make it possible to pedal my ride up to its top speed.

 

[John in CR]

Finally, a reason forcing me to gear so I always add pedal assist. Just in case, I'll need to put 2 freewheels in series on all my bikes.

That may be a reason for you, but without that particular reason it's still a wonderfull feature. My next build will be with a Schlumpf HS drive, to make it possible to pedal my ride up to its top speed.

I've always wanted to be able to pedal throughout my speed range. This is something that forces it. I've been planning an overhaul of my cargo bike anyway...put the batteries away, shorten the cranks, add an aero tailbox/cargo box, brakes lights and turn signals, change the motor's brake shoes, paint and lube, etc...I've got the space, so making one of my Nexus 3's a jackshaft and gearing for high gear to be a leisurely cadence at 40mph will be a piece of cake with no need for any derailleurs. Leisurely at 40 means I can still keep up at 55 on the highway as an attention getter when I pass cars.

Regarding catastrophic FW failure, my ears get hit by thunder all the time, so I hope it's far more rare. On a serious note, a cyclone rig had a similar failure and ejected the rider, so I really am going to try to protect myself with 2 in series on my bikes. Any pedal effort I add will be only for exercise, so losing a bit of efficiency in the chain line is irrelevant for me.

John

 

[SoSauty]

Read this about a FW crank seizing;

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=25153

It's in the Non-hub drive section.

 

[John in CR]

Read this about a FW crank seizing;

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=25153

It's in the Non-hub drive section.

That's why I linked to that thread in my resurrection post above. I remembered that this thread left off as "don't worry be happy", and I don't like bad info that poses a serious injury risk to be left hanging like that just in case someone does a search on the matter, like I did back in September. Cranks going from freewheeling to full lock instantly is a scary proposition. It may be rare, but it does happen.

My saving grace is probably that the cheap freewheel on my bike with somewhere close to 10k miles of freewheeling may not have strong enough metal inside for the same thing to happen. It still engages when I pedal, and is so worn that it's darn near silent...plus it's epoxied on due to left side install, so I don't want to replace it until I have to. I have a couple of Dicta FWs which sure seem like better quality and planned to put them to work, but a seizure failure after less than 1k miles on a FW not driven by motor power is scary to me. I'm not sure which would be worse an instantly locked FW at high speed or a front tire blowout at high speed on a sweeping curve. In a straight line I might be able to pull out a save with a blowout, but not on a curve.

John

 

[soap3000]

You have better chances of being hit twice by the thunder, than seizing a rear freewheel on your bike. Failure will be disengaging, or dislocation at the worst, nothing that would force you to pedal 60mph.

Not been hit by thunder [yet] but did have the rear wheel seize on me due to the pawl coming out of place. Was in the middle of a pack of around 20 halfway through a left hand turn, doing around 25km's an hour. Lost alot of bark on my thigh as I went down on my left side and slid my way along the tarmac. THANKFULLY I didn't take the rest of the bunch down, I was luckily in the right hand of the two lines that we ride in and roll through clockwise whilst training. One second I was freewheeling through a corner getting ready to put the power back on, then next second my rear wheel was locked up and I was sliding along trying [in vain] to keep the bike upright.

The seized wheel didn't cause my bike to turn into a fixie all of a sudden and spin my feet around as there's some slack in the chain and the springs in the rear dérailleur to be taken up before that happens. Once that happened the rear wheel just locked up and started skidding.

As I surveyed the bike after the crash I thought that the chain had snapped and become wrapped up in the rear cassette locking it all up. Both the front and the rear mech were mangled up as the chain was torn off the chainring and down over the crank to finish wedged against the pedal.

It wasn't until I'd got the spares and was going about repairing that I discovered that the chain was in fact intact and that it was the rear wheel that didn't want to freewheel any more.

I have to say it's really been mucking with my head, I'm a bottom end 'A' grader and have been averaging around 20,000 km's a year for the last 6 or 7 years and am now afraid to go over 40km/h for fear of having a fatal accident. Totally understand having a stack when it's pilot error [we've all had our fair share] but this just came out of nowhere.

I took the wheels back to a wheelbuilder who repaired them, said it was extremely rare and that I really should be sure to service them every 2 months if I want to be sure it won't happen again (who does that?)

Please tell me that this sort of thing is as 'rare-as-rockinghorse-poo'

 

[MadRhino]

Please tell me that this sort of thing is as 'rare-as-rockinghorse-poo'

I never seen a freewheel lock in 45 years of biking. I realized in this post that it happened to some, and I wondered a bit about what it would turn to when my rear hub motor is spinning 50mph. :|

I prefer not to think about it. Like my grandfather said: "Don't let the fear of death keep you from living fully."

 

[johnrobholmes]

I had one freewheel blow apart on me (cheap freewheel, powerful ebike, flexed until bearings fell out), but never have seen a failure of lockup first hand before in 26 years of biking.