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 Post subject: Re:
PostPosted: Sun Jul 15, 2018 11:35 pm 
Retro Guru
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Quote:
Did that first time around, just read them again, still confused

Well, I admitted to being baffled by this simple system, but I got what LongboardSi was saying immediately.

Forget 'bike' and 'gears' for a moment.

Imagine just a loop of chain engaged with a chainring.

The chain has one clearly marked link, sitting on one of the chainring teeth, which we will call: "tooth 1"

As you revolve the chainring, the marked link leaves "tooth 1", descends down one side of the catenary, reaches the bottom, and ascends up the other side of the catenary, until it reaches the chainring again.

Unless the number of links in the chain is an exact multiple of the chainring tooth count, the marked link will now occupy a different tooth from "tooth 1".

How far around the chainring that different tooth is from "tooth 1" is entirely dependent on the number of links in the chain.

That remains true regardless of any sprocket you might put in the loop of chain.


...It also remains true when you re-attach all that stuff to your bike..


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PostPosted: Mon Jul 16, 2018 12:37 am 
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Ok, got it that time, much more succinctly put.


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PostPosted: Mon Jul 16, 2018 6:55 am 
King of the Skip Monkeys
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Theres a 'bike' now?


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 Post subject: Re:
PostPosted: Mon Jul 16, 2018 8:51 am 
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Is that a deep philosophical enquiry?


@PeachyPM:
..and if my post was phrased properly, you should be able to substitute the word 'sprocket' for 'chainring', and 'chainring' for 'sprocket', and it will still hold true.

In terms of a given link visiting teeth, think of it as two independent systems; chain/chainring, and chain/sprocket.

All of that is quite seperate from the 1:3 'pulsation' issue, which I consider to be a chainring/sprocket phenomenon that is not much influenced for weal or woe by the number of links in the chain.

--------------

After miscounting my links, I now realise my single-speed chain is in fact 96 links, which, being a multiple of 16, means that a given link only ever visits one tooth on the sprocket, which is the worst case scenario in my book. Pesky vertical dropouts.. :evil:


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PostPosted: Mon Jul 16, 2018 4:59 pm 
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I wouldn’t worry too much about skid spots tbh. You’ll have the wheel in and out a few times for punctures and maintenance far before you wear the tyre out. Every time you take the wheel out you’ll put it back in a different position relative to the chainring so the whole skid spot thing becomes a bit irrelevant. I commuted for years with 48x16 which ought to wear the tyre out on one single point where it always stops, but I never even noticed this happen.


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 Post subject: Re:
PostPosted: Mon Jul 16, 2018 5:09 pm 
Dirt Disciple

Joined: Mon Mar 05, 2018 4:03 pm
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All good information this chain/ sprocket/chainring stuff no doubt, but did anyone mention-- Beware when oiling the chain etc with the bike in a stand as the flywheel advantage mentioned as benefit on hills can give you a nasty pinch if careless with revolving the drivetrain. It could even reduce your finger count. Many of us as kids experimenting with fixed gears and spinning up to see how fast you can turn he cranks did not realize what the consequences could have been.


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 Post subject: Re:
PostPosted: Mon Jul 16, 2018 5:20 pm 
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Quote:
I commuted for years with 48x16

Jonny69 do you think it possible that the number in your screen name was influenced by subconscious long term absorption of 1:3 pulsation?

Do you ever find yourself humming waltzes for no reason that you can fathom? :)


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