the 'there's no such thing as a stupid question' bike maintenance thread

i would hope the bike can cope with a bit of damp!

not so sure about the trainer though.

how 'worn' is a new chain?

because i was off the bike for several months, and sporadic other stuff getting in the way, i lost track of which cassette had how many chains on it etc.; and my chain wear checker only shows 0.75% and 1% wear, it doesn't have a 0.5% wear option.

anyway, on my 'good' bike the chain was showing not quite 0.75% wear; the checker was starting to drop into the gap but it definitely had not reached 0.75%.

so i bought a new chain, and hung it and the old one from the same spot from the shed ceiling(both on the same 3.5mm drill bit, FWIW) - and over about a 1400mm length, the old chain was somewhere between 2.5mm and 3mm longer. that's equivalent to about 0.2% extra wear over a brand new chain. but i assume a brand new chain would show 'wear' anyway.

FWIW, i'm going to clean it and put it back on the bike for now.

a google showed that a new chain would show 0.25% 'wear' upwards straight out of the box - i think due to tolerances in the pins and collars (or whatever they're called) allowing them to actually move?

one of the park tool chain wear tools seems to suggest a new chain can be between 0.25% and 0.5%:

i must take the new chain out again and actually measure it, making sure i have it under enough tension. see if it is exactly an inch between links.

if the chain, at the length i need it, is approx 140cm, that'd imply about 1cm of stretch at 0.75% wear, and i was only about a quarter of the way to that on the older one.

i did see a reference when looking it up last night that if the chain shows more than 0.5% wear straight out of the box, it's probably a cheap chain.

i haven't tried to diagnose it yet - but downhill from howth summit yesterday (past the cemetery), i realised my bike wasn't shifting down to the two smallest cogs on the cassette. just feels as if the shifter thinks it's bottomed out already - shifting up and down between cog #3 to #11 works perfectly. when you try to shift from cog #3 to #2, as mentioned, it behaves exactly as if you'd expect it to if you try to shift past #1. so i'm not sure yet if it's a cable snagging or something preventing the shifter itself from doing so.

(first time i'd tried to shift to those cogs in nearly a year, or first time i've noticed the problem anyway! ultegra 6800).

Definitely the shifter - I undid the cable and shifting down from top, it stops shifting two from the end. it's turned into a 9 speed shifter.

i've flushed it with some spary lube, leaving it to sit and penetrate for a bit and will try again.