Most common mechanical failures?

[vorsprung]

https://audaxing.wordpress.com/2013/08/01/common-mechanical-problems-on-london-edinburgh-london/

gear indexing
chain stretch
headsets
 broken spokes
rattling mudguards
luggage falling off
loose crank bolts

and a couple of other things

[Pedaldog.]

Mainly loose bolts, crank, Mudguards, racks and, Spectacularly, the Handlebars on my trike going Fippy-Floppy on a tight left hand bend!

On the Longstaff trike conversion, the freewheel is mounted at an odd distance inboard of the rear, bike frame, dropouts. Occasionally the chain goes beyond top gear and slips through between. Means much Oily, Sweary, lay it on it's side and chain splitting to get the chain out and carry on. It'll only take a 5 speed freewheel so, I assume, Ain't no quicklinky T'ing available.

Not punctures, but related, is Snapping Tyre Levers on certain B***ard tight tyres. First Trice puncture, 2002, I had to stop everybody that passed on a bike, or trike, and ask if they had a "Good Ole' Steel tyre lever".

[Moleman76]

Over 4 decades ago: lockring on a freewheel backed off, lotsa little ball bearings fell out.  Found a 5-6' long stick and "poled" myself home.  Semi-crusty veteran mechanic at the local (to college) bike shop had a loud "hmmpf" before selling me a Regina freewheel to replace the Suntour one which had self-disassembled.

About a decade ago: Son had 7-9 (my memory of the exact count is dimming) p*nctures on a 200-mile, one-day ride attempt (Seattle-to-Portland in the NW USA).  We got good at patching flats.  Finally took a really hard look at where the holes were - on the rim side - and determined that the inside of the single-eyelet bore for the spoke was just rough enough that it was rubbing through the rim strip.  Put a couple layers of paper in there and finished the ride - the second day.

Nothing much else to report

[rogerzilla]

I've had:

One broken spoke (on a crappy Halfords wheel)
Two snapped seatpost binder bolts
One cracked hub flange
One broken leather saddle nose bolt

I've seen:

One broken crank
One broken handlebar (hello Teethgrinder)
One broken Look cleat

All this excludes crashes.

It is worth carrying a seat binder bolt as a spare, since they are small and light but snap without warning (at any time, often when parked up), especially the Campag ones.

[The Family Cyclist]

I've had four rides that havge involved getting home not on the bike. Well one I scooted the bike as was 10 minutes walk from home when chain snapped. Was young skint and chain was well past change time. Other ones two rear mechanism s coming off. one must have worked loose one the hanger snapped and that took the rear wheel out as well. Other one a week after I had cycled through a deep flood my BB seized and actually unscrewed till the crank hit the frame.

[Brucey]

Over 4 decades ago: lockring on a freewheel backed off, lotsa little ball bearings fell out.  Found a 5-6' long stick and "poled" myself home.  Semi-crusty veteran mechanic at the local (to college) bike shop had a loud "hmmpf" before selling me a Regina freewheel to replace the Suntour one which had self-disassembled....

Years ago, I had a freewheel that undid its lockring, on a long climb in Norway.  I'd heard of this happening to a chum of mine, whilst touring abroad. Turned  out ( I found out later) it was the same climb....

I wondered if it was trolls....

But actually both failures were, I think, caused by there being a tiny bit of free play in the freewheel bearings.  This can allow contact between the lockring and the rotating part of the freewheel, and as one pedals, the kind of rolling contact that is made between the two parts encourages a very slight, but repeated, precessing action that can unscrew the lockring.  I suspect the particular climb in question is likely to be climbed in the small ring of a triple, but using some of the smaller sprockets, which is unusual and likely to provoke this sort of thing.

cheers

[mzjo]

Over 4 decades ago: lockring on a freewheel backed off, lotsa little ball bearings fell out.  Found a 5-6' long stick and "poled" myself home.  Semi-crusty veteran mechanic at the local (to college) bike shop had a loud "hmmpf" before selling me a Regina freewheel to replace the Suntour one which had self-disassembled....

Years ago, I had a freewheel that undid its lockring, on a long climb in Norway.  I'd heard of this happening to a chum of mine, whilst touring abroad. Turned  out ( I found out later) it was the same climb....

I wondered if it was trolls....

But actually both failures were, I think, caused by there being a tiny bit of free play in the freewheel bearings.  This can allow contact between the lockring and the rotating part of the freewheel, and as one pedals, the kind of rolling contact that is made between the two parts encourages a very slight, but repeated, precessing action that can unscrew the lockring.  I suspect the particular climb in question is likely to be climbed in the small ring of a triple, but using some of the smaller sprockets, which is unusual and likely to provoke this sort of thing.

cheers

When we were kids my brother had a freewheel do the reverse and tighten up solid. It was one of our scrounged and rebuilt Cyclo ones with springs made from strands of brake cable and we had left out one of the shims to try to take up the play in the bearings. Just out of Cheltenham, heading for the Kilkenny on the start of a hostelling week-end. It took out his re-cycled Huret mech! We went onto ss for the w-e, finishing with him on s-s using my rear wheel and me on fixed (advantage of a fixed/free hub), just for the pleasure.

I think in my list of breakdowns I forgot to mention the recycled Gran Sport mech that went into the rear wheel of my new Bob Griffin frame. It took me 4 years to get round to straightening the hanger and closing up the fork-end slot - rode fixed the rest of the time!

[ElyDave]

I forgot, one of the ACME Anvil winter series, the prescription insert of my cycling glasses broke, necessitating a quick run across the road to an ironmongers for some superglue

[Nick H.]

My travelling companion had a seized chain link on a new chain because of poor QC by the manufacturer. This was on a brand new tourer built up by Condor.

I had a lowrider dive into the front wheel because anything with P clips is asking for trouble. Luckily no spokes broken because the lowrider was a filthy Blackburn cheapie made of cheese.

And 6/7/8 speed Shimano indexing needs frequent adjustment to cure imprecise shifting. It was a crummy design, later improved enormously by Shimano. But after owning a beautiful bike with 10 speed indexing I regressed to 7400 for my next bike, despite knowing what clunkiness I was letting myself in for. 

[rogerzilla]

I've been wary of cantilever brakes ever since my new Cannondale assembled by Evans suffered total brake failure on its first descent here: https://goo.gl/maps/3wt7fjWgqBr.  The pads pushed right through the eyebolts of the Dia-Compe 986 arms because the nuts hadn't been sufficiently tightened.  Luckily this was just before I started using SPDs and I was wearing Spesh MTB boots with rubber soles, so I stopped by dragging my feet.  It took a lot of road.

[Nick H.]

Oof! Nasty. Maybe we need a separate thread for failures caused by bike shops.

If there was such a thread for motorbikes I'd add the time that a tyre shop left the rear wheel nuts finger-tight. I didn't quite crash and went back to remonstrate. All I got was a shrug. It's a good thing that I don't have a concealed weapons permit.

[Brucey]

..... 6/7/8 speed Shimano indexing needs frequent adjustment to cure imprecise shifting. It was a crummy design, later improved enormously by Shimano. But after owning a beautiful bike with 10 speed indexing....

not been my experience at all. Barn door clearances in a 6/7/8s system; you can almost throw it together and it will work. Shimano road 10s uses the same shift ratio etc so wasn't 'redesigned' much at all.  Something else to do with the specific setups you were using was probably making the difference, not the design.

cheers

[Samuel D]

And 6/7/8 speed Shimano indexing needs frequent adjustment to cure imprecise shifting. It was a crummy design, later improved enormously by Shimano.

What “frequent adjustment” are you referring to? Since moving to down-tube shifters I don’t frequently – or ever, really – adjust my 8-speed system. Eventually the loop of cable housing to the rear derailleur develops too much friction, but that happens on any system and its effect is progressively greater until 10-speed, since the cable pull per shift goes down. Furthermore, no “adjustment” fixes this. You need to service or replace the cable at that point.

As the pull per shift went down and Shimano routed the cables along the handlebars, the system got fussier about dirt and wear, and Shimano was forced to use more and more expensive cables and cable doodahs (‘tails’, etc.) to keep the effects of friction to a tolerable level. I wouldn’t call those changes enormous improvements although a Shimano accountant might.

Of course the shifts got ‘slicker’, i.e. quieter, as the sprocket count increased, but that’s an irrelevant change to me. I don’t care if the shift clunks as long as it happens instantly. It always does on my bicycle.

[Peter]

Lower back?

[hubner]

Obviously, punctures and tyre problems hugely outnumber all other problems.

If you maintain your bike, including keeping it clean and well adjusted, checking for loose nuts and bolts and parts and signs of problems such as cracks etc, then I would say actual breakages are very rare.

I would say broken spokes is the most common after tyre problems, because there's not much you can do to prevent broken spokes apart from a good wheel build and keeping it clean.

[andyoxon]

I've had:

One broken spoke (on a crappy Halfords wheel)
Two snapped seatpost binder bolts
One cracked hub flange
One broken leather saddle nose bolt

I've seen:

One broken crank
One broken handlebar (hello Teethgrinder)
One broken Look cleat

All this excludes crashes.

It is worth carrying a seat binder bolt as a spare, since they are small and light but snap without warning (at any time, often when parked up), especially the Campag ones.

I remember that happening on a FNRTTS ride*, outside Oxford, after midnight...

* whatever happened to FNRTTS? 

[Samuel D]

Agree that tyre problems are by far the most common on a well-maintained bicycle. This is especially true if you use lightweight tyres.

I can’t recall ever having a bolt come loose on my bicycle. Since I built my own bicycle and do all its maintenance, I can spend an economically mad amount of time cleaning the threads of every bolt, greasing as appropriate, and tightening to the specified tightness with a torque wrench. (I keep a list of the torque values for everything on my bicycle to avoid having to look up the scattered documentation each time.) This makes minor operations like replacing a cable or adjusting the handlebars take twice as long, but I don’t mind that on my own machine.

Bolts don’t back out without good reason. They hold important parts of aeroplanes together! Of course a good reason for them to back out is bad design, e.g. large radial loads on rear carrier bolts and the like. I avoid those bad designs wherever possible, and my bicycle has a strict minimum of things bolted onto it in the first place.

I see around me that battery lamps often give problems. Even when they emit light, they often have problems with how they are mounted to the bicycle (often the handlebars). Probably this was worse in the past when lamps and their batteries were much heavier, batteries were not soldered in place, and bulbs blew often.

[hubner]

Bolts don’t back out without good reason.

They can work loose from vibration, that's why it's important to check all bolts regularly.

Or they were installed too loose to start with. Or too tight eg a broken seat bolt, I think I broke a new Campagnolo one once, they shouldn't need to be all that tight.

[Brucey]

seat bolts based on the campag design break because they are a bad design; the bolt undergoes low cycle fatigue, in bending, as it is tightened, because it turns as the thing is tightened.

If you drill and tap the male part of the bolt (the piece that always breaks) and fit a length of studding in the (other) stationary part of the bolt, the studding will bend once and once only, because it doesn't have to turn any more. It thus won't break.

Bolts conventionally (in many other engineering applications) are long and stretchy, and are tightened to an extent which means that the service loads/vibration etc never (even for a fraction of a second) renders the bolt slack enough to allow it to start unscrewing.

 Bolts on bicycles are not like this; most of them are too short to stretch much and many of them are not tightened fully anyway (e.g. because the assembly is fragile in some way). In addition when you tighten a bolt onto a layer of paint, the paint will creep and the bolt will lose tension over time, and there are other settling mechanisms too.

All of the above means that using threadlock, nylock nuts etc is nearly always a good idea, and for many bolts if they are without such things, no amount of regular torqueing etc will result in 100% reliability.

cheers

[rogerzilla]

Gerald O'Donovan used to say that, when it all got too much, he was tempted to leave Raleigh Special Products and design something easy, like jumbo jets.

[Samuel D]

Ha!

It is true that bicycles hold an outsized fascination for engineers. A steel road bike is an object lesson in many facets of engineering, and yet it is within the grasp of an able individual to understand it all to a deep level. Maybe that’s the appeal? The hope, strictly false as it is, that you can understand everything there is to know about the whole machine. A jumbo jet will always have simplifying black boxes for any one individual.

Bicycles surely fascinate me unlike any other manufactured product, even though I’ve owned motorcycles and cars with more obvious engineering content.

[DuncanM]

I once tore a Brooks saddle near in half after clipping a pedal on my fixie (I hit it with my knee - it hurt!).
Otherwise I've broken spokes, a front brake cable, and a bolt holding my saddle to the seatpost, but all other failures have been down to poor reassembly.

[Thing2]

Hmm. We tend to carry a fairly comprehensive toolkit on the tandem, so normally can fix tyre, spoke and chain issues. We even managed to climb a couple of alpine passes one day  after a stoker crank fell off. Anyway, I think the only two ride ending mechanicals happened while touring and were :
irreparable chain damage and broken chain tool. We walked up hill and scooted along on the flat to get us to a train station.
broken freewheel leading to us limping on to the next town as a multi speed fixed bike (we were lucky we didn't have to go far, there wasn't much left of the axle by the time we arrived)
We managed to complete the ride last year when we snapped the drive side chainstay, but only by using alternative bikes.

[Brucey]

I have seen photographs of cunning 'splint' type arrangements which have been deployed when framesets and carriers have failed. Never had to do one myself, but a key ingredient often appears to be a cheap flat spanner, lashings of string, and hose clips/araldite.

cheers

[Thing2]

I have seen photographs of cunning 'splint' type arrangements which have been deployed when framesets and carriers have failed. Never had to do one myself, but a key ingredient often appears to be a cheap flat spanner, lashings of string, and hose clips/araldite.

cheers

We did consider that, but due to the position of the break (it was actually a weld failure), there wasn't enough clearance between the stay and the tyre for cable ties (or similar) where they were most needed.