Bicycle Brinkmanship....?

For discussions about bikes and equipment.
Brucey
Posts: 34269
Joined: 4 Jan 2012, 6:25pm

Re: Bicycle Brinkmanship....?

Postby Brucey » 25 Jun 2019, 1:42am

PDQ Mobile wrote:Brucey, you don't think regular pressure washing may be a cause of bearing failure?....


er, no. This particular bike gets left outside 24/7 and gets rained on, never cleaned per se. In fact it has green stuff growing on it in places.

Besides which the 'experimental pedal' (PD-M324) was one which had been abused to death by someone else. It must have been run with free play in the bearings, and the free play got so bad that the balls in the left bearing of the left pedal started to run over one another and escape from the place where they were meant to be. Since the cone has a hexagon on the end of it there was a certain amount of mangling; the cone was so far out of shape that I wasn't sure that the balls would even stay in place when I first reassembled the pedal bearing. There was a really bad tight spot and ninety degrees away from that the bearing was so loose that I thought the balls could escape again. Just what I wanted to try in fact.

You might be wondering 'why?' Well in my care I find that SPD pedal bearings just don't wear out; typically they need adjusting once (after they run in) and then rarely if ever need anything more than grease subsequently. However I have noticed that pedals which are run with any slack in the bearings (by other folk) do carry on wearing. Often I have had to adjust such pedals two or three times before they 'run back in' again, because the bearings wear to give a slight tight spot and a slight loose spot, which can gradually disappear over time if you keep relubing/readjusting. I was intrigued to see just how bad the wear would have to be before it became impossible to recover the bearings, i.e. so that they spin freely, have no tight spots, no free play and don't need adjusting more than once every few thousand miles/ couple of years. Some years ago I took what I thought were the most worn SPD bearings ever in another set of pedals (which were so worn that the bindings needed repair before I could use the pedals at all...) and gave them the same treatment and to my astonishment, after about four adjustments/regreasings the bearings 'ran back in' perfectly. Another year's use (without adjustment being necessary) confirmed that the bearings had settled down and were no longer wearing at any appreciable rate. Too easy then; I obviously needed a bigger challenge. Hence the current experiment.

In fact the current experiment almost failed because the RH ('control') pedal developed some free play. I hadn't regreased that one and (as is common for PD-M324) the seal on the spindle had deteriorated. So over the second winter some water got into the inboard bearing on the RH pedal so the RH control pedal developed more free play than the 'experimental' LH pedal (*). The RH pedal now has a little fresh grease and some improved seals, and has stopped wearing. The LH pedal bearings are still pretty rough but don't have a really bad tight/loose thing going on and don't seem to be wearing at any great rate. Several of the balls are damaged and when I last looked at them the edges of the damaged parts of the balls were well-rounded, which suggests that the bearing is settling down. Some prior examinations had revealed lots of swarf in the subject bearing. I've only bothered cleaning it out once though and it has done several thousand miles.

(*) from which you can conclude that even a really knackered bearing which is lubed with decent grease (solid lubricants, EP additives, synthetic oils and corrosion inhibitors amongst other things) can wear more slowly than a bearing with 'normal' (for shimano) grease which also has the slightest amount of water in it. The grease was still indentifiably green in places still, and only slightly brown (through corrosion) in others. It really is utterly hopeless grease if the slightest amount of water gets into it; no wonder that freehub bodies clap out so often.

So no, pressure washing has nothing to do with it. The provisional conclusion of this experiment is that if the wear is bad enough, you might not get SPD bearings to run back in again no matter what you do with them. But they have to be incredibly bad before that is definitely going to be the case. There are other experiments underway in the hubs and BB bearings....

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

francovendee
Posts: 840
Joined: 5 May 2009, 6:32am

Re: Bicycle Brinkmanship....?

Postby francovendee » 25 Jun 2019, 8:30am

I only have the one bike and try to run it on a shoestring, brakes do get proper attention but steering bearings, pedals etc get used way passed their best.
I use a different 'yardstick' for my wife's bike. She has little mechanical sympathy so things on her bike have to work properly.
I know what's worn on my bike and make allowances. For instance, the right side pedal sometimes makes a clicking sound (I expect there is a duff ball bearing in there) but the pedal doesn't jam up but is very loose. I will get around to changing it but it'd be long gone if it was on my wife's bike.

alexnharvey
Posts: 674
Joined: 10 Jan 2014, 8:39am

Re: Bicycle Brinkmanship....?

Postby alexnharvey » 25 Jun 2019, 9:24am

I am very interested in the idea of bearings wearing in. I was very interested in the old anecdotes of running a polishing compound in hubs initially to polish the races.

I have a brinksman special, a nexus 8r25 hubbed bike which I think dates to the early nineties. It has significant rust to the frame. I was given it via Freecycle the hub was full of rusty water. It has since had fresh bearings on the large ring cage inside the hub, a couple of changes of gear oil-grease mix and a new cable and runs very nicely.

bgnukem
Posts: 166
Joined: 20 Dec 2010, 5:21pm

Re: Bicycle Brinkmanship....?

Postby bgnukem » 25 Jun 2019, 11:59am

As I understand it, bearings don't wear in, but only wear out.

The initial surface finish of the balls and races is controlled and shouldn't really need to be any smoother. In industrial bearings, polishing of the races (removing the original grinding marks) is generally a sign of deficient lubrication, allowing metal-to-metal contact to occur between asperities on both surfaces.

Of course, in bicycle bearings the speeds are lower and loads generally higher so the lubricant does not keep the bearing surfaces separate and so boundary lubrication applies with rolling and rubbing contact occurring between surfaces. I wonder if any bicycle greases use EP additives to lubricate such contact, or would these simply become exhausted by the constant surface contact?

I know there have been extensive threads on the 'ideal grease' for bike bearings but they seemed to mostly suggest greases which are no longer obtainable (paper mill grease?) or only available in industrial quantities. Is there anything suitably fluid, water resistant with high film strength and perhaps EP additives out there?

Sorry a slight thread diversion but perhaps lubricating everything once with a 'proper' grease will help prolong the 'experiments' /tests to destruction mentioned in this thread?

mig
Posts: 1990
Joined: 19 Oct 2011, 9:39pm

Re: Bicycle Brinkmanship....?

Postby mig » 25 Jun 2019, 12:34pm

what sort of hammer have the rims had brucey?

i ask as i am still running a silver open pro for commuting that must be 20 years old and no idea how many miles it has been on the front of a (geared) bike. whilst i do keep the rim and blocks clean it does seem to go on forever that rim. overdue a replacement i would think but i never seem to get around to it.

Brucey
Posts: 34269
Joined: 4 Jan 2012, 6:25pm

Re: Bicycle Brinkmanship....?

Postby Brucey » 25 Jun 2019, 12:54pm

the classic ball bearing surfaces comprise hard steel parts that have surfaces that are somewhat hard and brittle. They usually make contact in such a way as the radius of curvature of the cup or the cone is slightly larger than that of the ball running against it. Thus the contact area is tiny and it is only enlarged by

- the viscosity of the lubricant; the film thickness, slight as it is, can 'spread the load'
- elastic deformation of the bearing parts; again slight but potentially significant.

Most hard bearings are hard at the surface only and if the bearing is subject to excessive load (eg if balls that normally share loads don't for some reason, or the preload on the bearing is excessive) then the surface can fail by subsurface fatigue; the result is that the cones and cups (and sometimes balls too) start to break up, crumble if you like. You can tell this is happening because there will be chunks missing and the fracture surfaces will be fresh and jaggy -looking. However if there is a little damage and the edges of the damaged regions are rounded, then this damage may have occurred some time ago and may not be ongoing at any significant rate.

There are subtle variations on bearing design and construction; in some bearings the radii of curvature better match one another from the start, so the contact is closer to line contact than a point contact right from the start. When you get a line contact between a ball and a raceway, there has to be some scuffing, but this is presumably tolerable if it only occurs occasionally under the highest loads. Thus in a SA 3s hub the balls almost exactly match the radius on the cones, and it takes something pretty dramatic to cause severe wear to occur there.

Additonally some cones appear to made of something different, that will tolerate some wear/plastic deformation without starting to crack up. I think some pedal cones are like this, hence the experiment. Some steels are designed to work-harden in service locally as required; I don't know that they are used in any bicycle bearings but then again I don't know that they aren't, either. Anyway if the bearing parts will tolerate some plastic deformation/wear without cracking up, you can get bearings that will 'run back in' to some extent. You can soon tell if this might be the case by examining worn bearing parts; the manner of wear is rather different.

Some bicycle bearings are designed to sustain the usual service loads 'one ball at a time' more or less; your typical 9 x 1/4" ball bearing in the rear hub is like this. If the bearing runs slack, it is normal to see damage arising from scuffing rather than overloads on a single ball at a time. Other bearings are not like this, they only work acceptably if the service loads are shared between balls; many modern pedal bearings (with small balls) are like this, with ongoing wear if the bearing is not kept adjusted.


SPD pedal bearings are interesting because a few tens of microns is enough to cause the pedal to feel distinctly baggy, and that is the sort of small wear/deformation that can occurr fairly quickly.

Imperfect ball bearings are annoying and presumably cost you a small amount in extra losses too. However a primary reason one should be wary of them is that once worn, they may be at some risk of catastrophic failure. My experience and my experiments to date suggest that in a cup and cone bearing (with a full complement of steel balls in it and no clip) the chances of a major blow-up are actually pretty small, provided the bearing is lubricated and adjusted correctly. Also, if the end is nigh, it will usually signal itself well before it is actually very dangerous.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Brucey
Posts: 34269
Joined: 4 Jan 2012, 6:25pm

Re: Bicycle Brinkmanship....?

Postby Brucey » 25 Jun 2019, 1:54pm

Re rims; there is a CXP22 at the front which is about 15 years old and this sees the brunt of the brake wear. At the rear there is Mavic Module E2 rim which is well over 35 years old now and has done the thick end of 80000 miles (I think). I don't use the rear brake much so it isn't badly worn. However the double eyelets are quite badly corroded; I put some waxoyl on about ten years ago and I have not inspected the eyelets since. I am thinking about retiring that rim because I can better use it elsewhere if it is good and it won't last indefinitely in the current usage either.

I shall add to this post the state of all the other bits.

-Tyres; both front and rear tyres have lots of cracking in the rubber but no sign of carcass failure as yet (I think because the carcasses are nylon). The tyres have been on the bike for at least three years but the rear tyre is about 15 years old, having been stored before use.
- Headset; Tange Levin steel, circa 1986. Runs loose balls and has an added seal ring in the lower race. It has been run fractionally loose for a long time now; the steerer is quite flexy and this means that the headset doesn't rattle as you go down the road, but does when you use the front brake.
- stem GB alloy, circa 1970. I have been told by several people that this stem is well overdue to break by folk that have broken multiple examples of this exact stem model. I occasionally check it for cracks at the most common failure point. The stem is drilled and acts as the hanger for the brake cable.
- handlebars alloy drops circa 1983. These bars have a centre sleeve but when I last examined them they had already suffered quite a lot of pitting corrosion. That was at least 20000 miles ago. The rear brake cable has worn most of the way through the centre sleeve in one place.
- bar tape; bar ribbon circa 1990. This has been on and off the bars about three times but is now so bad it is held together with wraps of insulating tape.
- brake levers; a mismatched set of weinmann levers circa 1970, which had new hoods in 1980 something. The hoods are now held together with sticky tape.
- brake cables - front stainless steel inner in M-system outer, about five years old. Rear some galvanised thing with rubbish housing, at least 25 years old now, for emergencies only.
-chainset; SR alloy 'silstar' cranks with a pressed steel non-detachable chainring. Now about 60000 miles (and at least a dozen chains) old. I should have scrapped it several times over, having run it too long with several chains, it has been 'rather noisy' for several hundred miles with a new chain.
- Bottom bracket; some cheap chin-huar/sun race thing with cartridge bearings. An experiment this; better seals and better grease when first fitted means it has lasted about seven years thus far (instead of about eighteen months) but has not been 100% play-free for the last five.
- chain; KMC B1 chain. it is about eighteen months old and has done about 3000 miles (I think). It quickly wore to ~0.75% then has worn much more slowly (and no it isn't the lube) and is currently about 1.25% wear I think. I could run it out to ~2% but the chainring will suffer (again)
- rear wheel; Mavic Module E2 rim and DT DB stainless spokes, built with double washers onto an ancient steel 3s hubshell, but with a modified FW internal in it, to S5 spec more or less. Wheel is about 70000 mile old now and has not broken a spoke. It was initially built with chrome steel Berg-Union spokes but they were not weatherproof enough. They also had low friction between the nipples and spokes, which is why the (very oily) nipples used to back out rathe easily. The berg spokes lasted about two years so its been DT ones for nearly 35 years now. Ancient four-speed axle broke two or three years ago and was replaced with another. Other than that and (self-inflicted) corrosion damage, hub has been very reliable. Rim tape is some ancient (and cracked) Michelin thing with (now hardened) insulating tape over the cracks; living on borrowed time.

- front wheel; current front wheel is about ten years old and is built from used parts. It is an experiment to see if there is a long term cure for the cones (that break up and can't be replaced now) in DH-3N71 hubs. The bearings have been through about four different setups and are currently failing (again); the hub makes some very nasty noises, but mainly when wheeling the bike around, not when it is being ridden. The hub has also seized solid through internal corrosion before now; water gets into the generator itself and causes all kinds of problems.

- Lights; a £15 front Union LED light which has screws so corroded on it that I can't open it up any more. Rear light is home-brewed LED conversion in an old dynamo rear light, all running off the DH-3N71 hub.

- brakes; Mafac-type weinmann rear canti (circa 1982?), shimano front. The front brake had those terrible plastic spring shrouds that broke; I made something different for it but the springs have never been perfect. Currently there is less than 1mm of front brake block before the XTR type holders hit the rim....

- seat pin; some Italian fluted alloy job, circa 1986 with steel cradle parts. The bolt threading is (I think) M8 x 1mm and the threads are damaged.

- saddle Milremo 'Arius' (close relative of Cinelli), circa 1978. It lost its suede/foam near the nose some years ago and has sticky tape repair and a cover to hide its blushes.

- mudguards; mismatched chromoplastic with custom-made stainless steel hardwear. I got so cheesed off with the rubbish you could buy I made my own stays, brackets, and mudflap.

- pedals currently PD-M324 with an ongoing experiment.
- shifters; modified (cheap) shimano thumbshifters (modified to work S5 type hub gear) mounted beneath the stem on a special bracket. Shifters were old when I mounted them. Cables are now about 25 years old, and SIS housing is due to burst, judging from the cracks in the covering.

- Frameset; claud butler circa 1969, with 531 forks and gas pipe main tubes. Lots of special braze ons. Frame broke several years ago and I welded it back together again. The break (if not the repair) it a lot like the African bike pictured upthread. Paint is mostly tatty or non-existent.

So you could say I have had my money's worth; I ride this bike almost every day....

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

ElCani
Posts: 85
Joined: 5 Mar 2015, 11:24am

Re: Bicycle Brinkmanship....?

Postby ElCani » 25 Jun 2019, 10:12pm

Pics!

mig
Posts: 1990
Joined: 19 Oct 2011, 9:39pm

Re: Bicycle Brinkmanship....?

Postby mig » 25 Jun 2019, 10:25pm

the saddle model name is a joke right? :D

would you bomb downhill on it and survive a sweeping turn at the bottom?

Brucey
Posts: 34269
Joined: 4 Jan 2012, 6:25pm

Re: Bicycle Brinkmanship....?

Postby Brucey » 25 Jun 2019, 11:01pm

mig wrote:the saddle model name is a joke right? :D


it is quite funny but no it is a real thing

http://hilarystone.com/saddlesCinelli.html

I have some 'Cinelli' branded saddles which are built on 'Arius' hulls too.

would you bomb downhill on it and survive a sweeping turn at the bottom?


Probably. But I have not inspected the steerer for a couple of years; that might put me off.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

cycle tramp
Posts: 504
Joined: 5 Aug 2009, 7:22pm

Re: Bicycle Brinkmanship....?

Postby cycle tramp » 26 Jun 2019, 10:45pm

ElCani wrote:Pics!


Definitely! Personally I'd take loads, then write an entertaining article about the history of the bike, sell it to a magazine, as proof that you don't need a mega expensive sports bike to cycle 4 miles down the road.... and then rebuild it on the resulting profits:-)

User avatar
Patrickpioneer
Posts: 275
Joined: 25 Sep 2017, 11:18am
Location: Brynteg

Re: Bicycle Brinkmanship....?

Postby Patrickpioneer » 27 Jun 2019, 5:52am

Bruce's description of his bike reminds me of this song :D
https://www.youtube.com/watch?v=18cW_yHo3PY

JakobW
Posts: 251
Joined: 9 Jun 2014, 1:26pm
Location: The glorious West Midlands

Re: Bicycle Brinkmanship....?

Postby JakobW » 29 Jun 2019, 10:35pm

+1 for pictures of the Bruceymobile...