Gravelmark

As I convert our Cannondale over to a 12 speed, I got to wondering what is the reason the timing chain can't be the same. This would save on extra links etc. I have found single 12 speed rings but beyond that, what are the concerns. Wouldn't the "power" to the rear wheel (using the 12 speed chain) be the same as the power to the timing chain? I could be missing something....

TobyGadd

Edited after reading bwebel's excellent post below. Seems that the inner dimension of all chains is the same, it's just the outer chain dimension that's gotten narrower with newer chains. Thanks, bwebel, for making me do my research before posting. Here's a good article on the topic: Tech FAQ: Chain width explained, compatibility queries answered - VeloNews.com

While I didn't used to believe that a thinner chain would be as durable as older 8-speed chains, the opposite has actually turned out to be true: Finding the best bicycle chain: What over 3,000 hours of testing revealed - CyclingTips.

bwebel

You don't really need to match the timing rings to chain in the sense of, for example, 9 speed chain and 9 speed rings. The primary difference between the different speeds of the chains is the outside width, which matters because of the rear cog spacing, and somewhat less because of the possibility of the chain falling between the rings when you are shifting the front derailleur. Neither of these matter on timing chains. The only issues you might run into are the with newest, such as the SRAM's flattop chains and the Campy 13 speed. Otherwise you can use pretty much any "speed" chain as a timing chain with pretty much any rings.

Gravelmark

Good info! Thanks, I'm going to go with the SRAM eagle 12sp chain to match the drive. This way I can keep only one style of quick connect, etc.

LV2TNDM

This is a good discussion worthy of further debate...

You're pretty much going to see full compatibility between all multi-speed chains when it comes to using them on a single timing chainring. However, there are aspects of chains & rings worth discussing.

My 10-speed Co-Motion was equipped with an 8-speed timing chain. When I replaced them, I went with the same configuration. The advantage is that an 8-speed chain has more material in the chain which SHOULD reduce wear. And from what I've gleamed through discussions with industry folks AND personal experience, timing chains actually wear FASTER than main chains. This seems to defy logic as a timing chain only has the power of one rider going through it, whereas your main chain has to withstand the power of two riders. However, since a timing chain only passes through two effective arcs or "chain angles" (straight, and the arc of one timing chainring), wear is increased. A main chain is traveling through up to three different-sized chainrings and 9, 10, 11, or 12 different sized cassette cogs. Oh and then the chain goes around two derailleur pulleys too! These many differential chain angles encountered will tend to "spread the wear" out through more of the chain's effective rotational range. Or at least that's the thinking.

So since timing chains can wear faster, it makes sense to use a "beefier" timing chain. However, are 8-speed chains TRULY "beefier?" Therein lies the question!

The other question is if you can truly find "8-speed chainrings" that are thicker than higher speed rings. Doubt it. But if you could, I would. And if you could get thicker 8-speed timing rings, they'd be even BEEFIER if they incorporated "narrow-wide" chainring teeth like seen on today's 1X setups. THAT would be ideal. Hey wait, looks like a business opportunity right there!

"LV2TNDM'S SUPER STRONG WIDE-NARROW 8-SPEED TIMING CHAINRINGS SOLD HERE!!!!"

And yes, carrying only ONE size spare quick connect and links does make a whole lot of sense. So going with matching 10, 11, or 12-speed timing chains does make sense.

Or just switch to a Gate's carbon belt and end this nonsense discussion!

TobyGadd

Yes, this seems hypothetically accurate--and I made the same assumption for years. But, according to the link provided in my prior post, testing has shown that it's not true. They found that more speeds = longer life. A worthy read. Zero Friction Cycling takes this stuff very seriously, so I find no reason to disagree with their results.

Gravelmark

I looked at a gates but for some reason, my Cannonade doesn't have the correct bb to bb measurement. Chains it is!

due ruote 

I can't comment on the lifespan data mentioned so far, but it should be pointed out that 8 sp chains are less expensive, so even if they need more frequent replacement, they could still be cheaper on a cost/mile basis. At least excluding any penalty for carbon offsets. I will let someone else do the math on all of this...

LV2TNDM

"More speeds = longer life" would support the notion that narrower chains require higher quality steels to maintain minimum strength & performance standards. And when a narrow 12 speed chain is approved for tandem use, you know it's pretty stout. So I can appreciate this conclusion.

Chilepines

My understanding is that chain wear is at the pins not the plates. Chains wear from dirt getting into the pins and rollers and creating a small gap where the pin pivots. It's not the plate that wears out or stretches. And a thicker plate would not reduce wear, it would reduce how fast the plate wears out. And as others have said, narrower chains are actually stronger because they have to be made to tighter tolerances.
We are now running 11 speed with Silca Super Secret chain lube which is wax based - the chain does not get dirty or rust the way oil lubed chains do.

longpete

Narrower chains have narrower plates and narrower pins. That's our problem with 11 speed chains. Links start to come loose from the pins before the chain is worn 5 mm. So I prefer a 8/9 speed chain for timing chain. For the waxed driving chain I carry a lot of quick links with me.

sch

OTOH how much do a few extra quik links weigh, or even a few chain links for two chains? IME timing chains on
tandems last ~3x at least longer than drive chains, IIRC our last timing chain lasted 11K miles where drive chains
last 3-4K miles. Apparently that straight line drive reduces wear rate considerably. An 8 or 9 spd timing chain
seems ok to me and that is what we used. FWIW a Gates belt is sposed to be good for 20k or so miles.

IPassGas

On both our derailleur and rohloff (straight line) tandems the timing chain lasts about 3 times longer than the rear chain. Many years of data. The rear chain has significantly more force on it. In addition, the rear chain also picks up more trail dust. I do not understand why more dust, maybe the front wheel spews dusts that tends to miss the timing chain. This is also true for rohloff where the chain is further from ground (no derailleur). Typically 10,000 miles on timing, 3,000 on rear. We considered Gates belts, but limited to 1 size and does not provide sufficient stoker space (we are tall).

scycheng

I tend to keep the timing chain to be the same as the rear chain simply because if I wreck the drive chain really badly (twist/mangle), I can always use the timing chain as the drive chain and use any chain(s) (5,6,7,8,9,10,11,12 speed) as the timing chain to hobble to the nearest bike shop where I can find the right chains.

Probably never will happen but just in case.

Carbonfiberboy 

Or like some friends of mine, have a timing chain issue and find that you only have quick links for the drive chain. Quite annoying on a hilly gravel ride.