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Weight saving?

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Dave....
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PostPosted: 22:15 - 06 Mar 2018    Post subject: Weight saving? Reply with quote

Wrong on so many levels.

https://i.redditmedia.com/64r2JqAgJ4DIfZhb3afd8s9UM3yjShS-UKxCEkHKEf4.png?w=625&s=c086463feeceb2a782eb2a750063ff3b
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Bikeless
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PostPosted: 22:45 - 06 Mar 2018    Post subject: Reply with quote

No cush drive?
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Raffles
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PostPosted: 22:56 - 06 Mar 2018    Post subject: Reply with quote

At least the split link is fitted the correct way round.
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DRZ4Hunned
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PostPosted: 23:35 - 06 Mar 2018    Post subject: Reply with quote

Can't imagine chain lube and brakes is a very good combo.
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Fisty
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PostPosted: 23:37 - 06 Mar 2018    Post subject: Reply with quote

Bogeyman wrote:
Looks like some gay home brew frankenstein bike.

Could be ThatDippyTwats.


At least the sprocket is not welded on.
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pepperami
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PostPosted: 23:46 - 06 Mar 2018    Post subject: Reply with quote

On a serious note?
Could that be an old motocross bike?
In sandy environments , chains are not lubed as much and changed more often.
Sand would/does stick to the lube, making a grinding paste Shocked

Could it be off a concept bike?
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RhynoCZ
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PostPosted: 23:46 - 06 Mar 2018    Post subject: Reply with quote

I saw this on Tv once, one of those custom chopper shows on Discovery. They even had the sprocket chrommed. Neutral

But not to be so negative. With dry-lube this could actually work very well, regardless of the novelty of the whole idea. Not talking about the chromed brake disc, that I was talking about earlier.
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ThatDippyTwat
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PostPosted: 00:12 - 07 Mar 2018    Post subject: Reply with quote

Bogeyman wrote:
Looks like some gay home brew frankenstein bike.

Could be ThatDippyTwats.


I've proper tickled your fancy, you've really got a semi-on for me, haven't you Ashley?

On Topic - Seen a few on Harley's over the years, never struck me as a good idea.
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Freddyfruitba...
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PostPosted: 01:24 - 07 Mar 2018    Post subject: Reply with quote

Raffles wrote:
At least the split link is fitted the correct way round.

Hmm. You're assuming that's the rear wheel... Shocked
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wr6133
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PostPosted: 10:04 - 07 Mar 2018    Post subject: Reply with quote

When it warps I wonder if it would throw the chain.
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stinkwheel
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PostPosted: 10:35 - 07 Mar 2018    Post subject: Reply with quote

RHS chain so something slightly oddball and european.

Sometimes the cush drive is on the clutch.

On old Brits, it was common to have the brake drum and sprocket in a one piece casting that slots into the cush drive on the wheel.

Mind you, size of that central nut, maybe it's a single side swingarm?
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Teflon-Mike
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PostPosted: 11:08 - 07 Mar 2018    Post subject: Re: Weight saving? Reply with quote

Dave.... wrote:
Weight saving?

Probably not..... curiously.... but actually NOT such a completely 'daft' idea.

'Principle' has some merit. The ratio of sprung to unsprung mass is far more influential than how much all-up mass you have, so every ounce you take off the swing-arm is umpety times more useful than taking it off the frame.

Brake discs, are usually made of iron or steel. In olden-days, big weight savings could be made substituting an alloy hub for an iron one, or an alloy rim for a steel one... but, you had to go to a full cast-alloy wheel to save much more. Going to disc-brakes over drums, then can actually start to rob weight saving, and significantly not just un-sprung mass, but rotating mass, adding heavy cast iron or steel discs to the wheel, where friction area in a drum is integral to the hub.

One of the reasons that brake discs have got bigger over the years, and are almost as big in diameter as the rim of a 17" wheel they are fitted to.... a-n-d to try and keep the weight down, often only the 'swept-area' of the rotor is iron/steel and supported floating mounts on an alloy carrier, or sub-rotor.

On some of the old Brit-Bikes, rear-hubs were made of cast iron, and to try save 'some' of the weight, the sprocket was cast integral with the brake-drum... great as long as the sprocket didn't wear out.... then you needed a new hub, or some-one to cut the old teeth off on a lath and shrink on a replacement!

Now, actually easier to cut a sprocket from alloy than from steel. Its cheaper and lighter. And years-ago, such replacement sprockets were critasised as being "monkey-metal... wunt-last!" which compared to how long steel lasted was probably reasonably true... any-one ever had to replace the steel rear sprocket on a push-bike?

But as engine power increased, the need to make chains & sprockets wider to take the load, negated such tenable advantage, and chains made of steel still tend not to last as long as sprockets, so if you have to change them, what small hassle swapping sprockets too.

Oh-Kay... Interesting aside, Edward Turner, after a visit to the Honda Factory in Japan in the early 1960's, contrary to popular lore, offered dire warnings about the 'threat' of Japanese manufacturing.... that were roundly ignored on the grounds they only built 'tiddlers'... at the time... 1967, Honda revealed the 750-Four to the world, and curiously Triumph dispatched one of the Lan-Tech's from Unberslade hall to order one of the first examples in the country from the importers..... He rode it half way back from London, when it arrived, and had to be trailered from some-where near Oxford... it didn't manage its sixety mile maiden voyage, snapping its drive chain en-route and smashing the crank-case when it went! Causing much Ridicule by the BSA-Triumph engineering team.... But Mr Turner, allegedly commented, 'They'll sort it!"

By the 1980's, they had, and making Chain & Sprockets a 'service-spare' to routinely replace, was party of that solution... even on lighter-weight machines, like a 250 Super-Dream, where perversely it actually became a sort of sales feature to have to replace C&S on one like you did a 'big-bike'?!?!

Meanwhile, wheels had switched from the usual wire-laded steel-rimmed assembly to the one-piece cast alloy item, and cush-drives, in the rear-hub, had become common, to reduce drive-line 'snatch', even on light-weights.

Carbon-Fibre was an ultra modern exotic material at the time, and incredibly Honda were pioneering its use, if in rather conservative ways, not least to make wheels.

The Honda Comstar, 'composite' wheel, was intriguing in that it retained the seperate hub, rim and spokes of earlier wire-laced wheels, but using pressed plates in place of the wire-spokes, and The first 'Carbon-Fibre' wheel I am aware of was a Honda 'Comstar' used I believe on the NR500 back in 1979, with CF spoke-plates.... that broke.. but they sorted it!

Which is to illustrate how rapidly more advanced materials were employed to make lighter wheels for the all important lower unsprung mass...

One of which, was the suggestion of 'Plastic' sprockets.... which apart from some nylon examples being offered for sale in the early 80's haven't really taken off... but remain interesting and pertinent here.

The nylon sprocket, was supposed to have the advantage of being even lighter than an aluminium one, whilst having inherent 'complience' negating the need for a heavy cush-drive.... whilst being durable enough to last as well or better than ali sprockets.....

Now, whilst this remains interesting, out of that almost no-holds-barred bit of the techno-race, the intriguing thing is that overall, Aluminium sprockets proved that they were something of an all-round optimum for cost, longevity, and weigh....

A-N-D getting to the point.... on a larger sprocket, the all-up mas of the whole component, was no heavier than the teeth alone, on a similar diameter iron/steel one....

Which begs the query really, cutting sprocket teeth into a brake-disc rotor, DOES it actually save much if any weight over a smaller steel/iron brake rotor and ali-sprocket?

Practicality issues asside..... idea of oiling a chain tugging on a brake disc does not seem like the smartest of ideas, but as has been suggested, that may not be such a big issue.

The ride of the sealed 'o-ring' chain, would offer itself as president here. In an O-Ring chain, the lube for the links in the chain is sealed into the links by the O-Ring. In theory they should 'only' need lubrication on the outside of the chain 'briefly' to ease the take up on the sprocket, between the roller and the sprocket tooth.. once in contact the roller should remain stationary to the sprocket tooth, so no movement no wear, no lube needed.....

In the old 50 & 80cc GP classes, it used to be common practice I believe to run chains lub-less, and I have accounts of chains being 'burned off' after dipping in oil, to remove the oil, and leave a light coating of soot, or graphite carbon, that acts as a very good lubricant, and in some sports like push-bikes or radio-controlled models, is actually quite common to 'dry-lube' with powdered graphite rather than oil.

Using spheroidal iron, that has notable self-lubricating properties and is most commonly used for gears in Helicopter gearboxes, so they don't seize if they suffer oil-loss, offers alternative way that 'enough' lubrication for the outside of the chain-roller during take up onto the sprocket could be provided without wet or splash lube.

As said, its not an utterly ridiculous bit of engineering... there could be some very sound engineering reasons behind it.... whether its a well engineered solution to anything, though remains another question!
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stinkwheel
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PostPosted: 11:18 - 07 Mar 2018    Post subject: Re: Weight saving? Reply with quote

Teflon-Mike wrote:
any-one ever had to replace the steel rear sprocket on a push-bike?


Yes. Especially 11 tooth ones. They are often seperate to the rest of the casette and made of high tensile steel. Mrs stinkwheel gets about 2 years out of one.

Just had to replace the front sprocket and track cog on her fixie because it was pointed like a sherukin and jumping teeth (that was fun to find, late 70's SR chainset with a unique bolt circle diameter).
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Teflon-Mike
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PostPosted: 15:04 - 07 Mar 2018    Post subject: Re: Weight saving? Reply with quote

stinkwheel wrote:
Yes.

Thinks....Fairly rare..
stinkwheel wrote:
Especially

But there are exceptions... tries very hard not to imaghine the size of thighs.. or anything else... needed to warrant that.. spots 'Bovine proctologist' next to user name, and tries very very hard to find something else to ponder!!!!
stinkwheel wrote:
11 tooth ones.

AH! There, 11 teeth.. that's not a sprocket that's a geometry excersise from school.... thinks protractors... oh shit., too close to proctologist.. CHRIATMANS TREE FAIRIES! THINK top of the Christmas tree.... NO!!!! This isn't helping! Dark room! Need dark room! NO I don't want flash-backs to the film "Little Nicky!" Pineapples!!! Meds! Need meds! Lol!
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Freddyfruitba...
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PostPosted: 15:43 - 07 Mar 2018    Post subject: Re: Weight saving? Reply with quote

Teflon-Mike wrote:
AH! There, 11 teeth.. that's not a sprocket that's a geometry excersise from school.... thinks protractors... oh shit., too close to proctologist.. CHRIATMANS TREE FAIRIES! THINK top of the Christmas tree.... NO!!!! This isn't helping! Dark room! Need dark room! NO I don't want flash-backs to the film "Little Nicky!" Pineapples!!! Meds! Need meds! Lol!

You are Admiral Uhura Adam Kirk Branson Cheshire Cat and I claim my £5
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MarJay
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PostPosted: 16:13 - 07 Mar 2018    Post subject: Reply with quote

I have to say that lube doesn't really get on my rear sprocket. If you lube the chain as you are supposed to, then I can't see this being an issue. In fact, I'd guess it's fairly efficient as it reduces rotational mass and unsprung weight. When rear brakes are often only fitted for MOT purposes anyway I can't really see a problem.

The rotation of the disc/sprocket should keep any errant lube off of it anyway. Just don't use a scottoiler I guess.
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stinkwheel
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PostPosted: 16:18 - 07 Mar 2018    Post subject: Reply with quote

Most racer bikes have an 11 tooth sprocket. 52/11 is usually the highest gearing for standard road bikes.

I was working on a kids mini motorbike the other day that had a 4 tooth front sprocket. Those don't last long.
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Old Git Racing
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PostPosted: 16:57 - 07 Mar 2018    Post subject: Reply with quote

Could be a 3 wheeler (2 front 1 back).

OGR
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