Which missing links fit the KMC X8-xx and KMC X1 chains?

[Andre Jute]

KMC MISSING LINKS FOR 7 AND 8 SPEED CHAINS

There's some confusion about which missing links (also called quick links and !@£$%^&*()_!!!!) fit which KMC chains. KMC's missing links are packed in identical, easily confused, bubble and card containers but are differentiated by width, marked in red below. The X1 has a separate "silver" (probably nickel-plated) missing link but it seems likely that a more pedestrian KMC link of the right width will fit in an emergency.

KMC MISSING LINK 7/8SP
WIDTH 7.1mm
FITS KMC Z8 + Z8RB chains
SRAM® 7-speed + 8-speed chains
Re-usable

KMC MISSING LINK 7/8SP
WIDTH 7.3mm
FITS KMC X8.99 + X8.93 + Z8XRB, Z7 + Z6 chains
Shimano® UG51 + HG40/50/70/90 chains
Re-usable

KMC MISSING LINK 1 SILVER
WIDTH 7.1mm
FITS KMC X1 chains
Not re-usable

A few notes, some from memory:
-- The Z6 and siblings lower down the KMC quality scale (Z5? Z4?) were/are popular in the aftermarket for off-road bikes and I remember that they were said by knowledgeable cyclists to be very good value for money; they are also fitted as standard on quality off-road bikes.
-- I've had some kind of a Z8, fitted as original equipment by a German baukast (custom house) often said to be the "Rolls-Royce of German bicycles" (an accolade that after ten years of use, and having kept Rolls-Bentley in the past, I see no reason to criticize); it is a good chain, made specifically for hub geared or other single-speed bikes; last I heard, they were fitting the X8 instead, the X8 being a derailleur chain more generally available and, I suspect, cheaper even in bulk than the theoretically less expensive Z7/8. I too have used the KMC X8 in both the available variants for a decade or so, and found them simply better than any other chain I've ever had. Since I operate all my bikes with fully enclosed chains, I'll wait to buy an X1 (or not) until all the reports are in.
-- Notice in the above table that the two pre-X1 7/8 speed links differ only in width.
-- Notice further that, contrary to KMC practice in their other missing links, which are all re-usable, the special missing link for the X1 is not re-usable. To me, that will be another reason, on top of the less-than-overwhelming mileage reports, not to buy the X1 and to stick with what I know and have a stock of, the X8.
-- I would guess that in an emergency an older link of the right width will fit the X1 too.

[rafiki]

What is the reason for the X1 link being un-re-useable?

[Andre Jute]

What is the reason for the X1 link being un-re-useable?

I don't know, Brian.

Speculation:

1. It may be nothing more than the greed, to turn the X1 missing link into a profit centre.

2. The X1 link is described as "silver" rather than "stainless". We know the rest of the chain is stainless, because that is its USP (unique selling point). "Silver" may be nickel plating over steel. Against stainless, it's likely to wear faster. That's a perfectly good engineering reason to specify the missing link as single-use.

3. Considering the slotted design of the missing link, it offers more opportunity for unwanted movement, not to mention opportunities for getting itself skew because the two slots are diagonally across the link, than any other link in the entire chain. Wear would enhance these opportunities for things to go wrong, accelerating further wear. That too is a legitimate reason for scheduling replacement sooner rather than later, which a single-use rule achieves handily.

4. A steel link could be inserted deliberately in a stainless chain as a sacrificial component, again for good engineering reasons unknown to us.

5. In my view the most likely reason is that a stainless missing link's side plates would require more power than resides in the fingers of most cyclist to flex them enough to disassemble/reassemble the link, so they made it steel for convenience and plated it with nickel for appearance, and want to protect their brand by not having X1s running around with one scratched, rusting link, so they tell buyers it is not re-usable.

Choose one, more, or all.

[rafiki]

What is the reason for the X1 link being un-re-useable?

2. The X1 link is described as "silver" rather than "stainless". We know the rest of the chain is stainless, because that is its USP (unique selling point). "Silver" may be nickel plating over steel. Against stainless, it's likely to wear faster. That's a perfectly good engineering reason to specify the missing link as single-use.

Interestingly, the box in which my recently arrived chain is packaged is also marked 'Silver'.

[Dave Whittle Thorn Workshop]

X1 missing s have little locks on them with deform when undone, as its marketed as a Rohloff chain KMC lead me to believe this is because many Rohloff bikes run a tensioner which can catch and unship the joining links.

So its fine ON THORN BIKES WITH EBB's to use the 7/8 7.1 version, I also PERSONALLY think you would be fine to reuse the X1 versions on our bikes.

Please note all the above is only my own opinion. 

[Andre Jute]

Thanks for that, Dave. Therefore an engineering reason to do with the transmission configuration of other classes -- than touring bikes -- for which Rohloffs are also marketed.