Why didn't that work? Went from a 40tooth dedicated singlespeed ring to a 38tooth narrow wide. Took one link (i.e. outer and inner plates) out of chain and it was waaaay too tight.
Am I being a numpty?
Yes. The chain only goes halfway round a chaining.
Is the 38t ring brand new? Those few mm of wear make a difference! I tried to put a new SS chain on mine on 32/17 and it was just too short, no way it'd work, but a worn chain fitted fine.
New chain or old chain?
If new chain then the old one was stretched.
If its the old chain then the new chainring is forcing it to sit higher on the teeth effectively increasing its diameter as the links are now 1/2" and a smidgen. On the old chainring that wouldn't be a problem as the teeth are worn as well and the chain only really engages with the first tooth once worn.
As above you're not engaging two less teeth.
Also in the interests of pedantry, outer and inner plates is two links, each set of plates is one link... (The link being the pin/roller which actually links the plates)
[Afterthought] Or just what theotherjohnv said, its only 1and a smidgen smaller (you gain a bit as the diagonal from the chainring to sprocket is slightly less also)
Get a chain tensioner.
I did wonder about the mixed vintages of components, I'm just experimenting with different cranks/ratio so it's an old narrow wide mixed with a less old chain that had been running on an even older chainring! So who knows basically.
Given how much slack I have with the original chain length, and how tight it is with two tooths worth removed (I always thought that was the definition of a link, hence 'half link' only being one set of plates?) I think JonV has it.
And so also does rydster, I really hate trying to balance correct chain tension with a propely aligned wheel on horizontal drops, time to readjust brakes again and order some chain tugs...
And so also does rydster, I really hate trying to balance correct chain tension with a propely aligned wheel on horizontal drops, time to readjust brakes again and order some chain tugs…
I'm sick of it too. It's very fiddly and the chain stretches so it needs adjusting over time.
If I run a SS again it will just be on vertical drop outs and I'll use a chain guide and tensioner.
Less of the 'think jonv might have it' please. I do have it. It's a fact. The chain is engaging 19T around the 38T ring, and 20 on a 40T ring. A pair of links (one ea inner and outer) engages two teeth, so if you dropped a pair out of a chain you also need to drop 4T off the chainring
TINAS is also right, trig means the chain is a bit closer to parallel so a bit shorter, but the difference is minimal (otherwise your couldn't run an oval on a singlespeed - and you can)
Ooops, sorry sir! 😉
Outcome is I stuck with the original chain length, moved the wheel back in the drops, and now enjoy a perfect chainline thanks to the old Alivio cranks I found in my dad's garage, which are also lighter than the old cranks. Bit odd that the chainline was out using all singlespeed specific cranks, hubs and frame and it took a triple chainset to rectify it...
Having to drop a gear very slightly did mean I seem to spin out at 20mph on the flat now, but hey, it's a winter base miles bike.
I was just joking 😉
thanks to the old Alivio cranks I found in my dad’s garage, which are also lighter than the old cranks.
Old Alivios are lighter? WTF did you have on there before!!
Haha, so was I, the curse of not enough suitably expressive smileys!
The stock cranks weren't bad, they just weren't hollowtech, basically solid, square section aluminium.
In fairness by 'lighter' I meant 'felt lighter in the hand once I'd made a mental subtraction for the weight of the pedal still attached to the stock crank' e.g 'probably not lighter'.