When to carry a spare tyre?

[mzjo]

As someone who's successfully joined 9-speed chains (on recumbents where necessary use of gears means they aren't normally subject to enormous amounts of force) I'm quite annoyed that the otherwise competent chain tools built into multi-tools are nearly always the break-only type.  Better to have the option, surely, especially if there's single-speed involved?

I'll take your word on it, I'm too poor to afford a multi-tool with a chain tool on it (and probably too stupid to work out how it works). My Decathlon one seems to work ok for me.

[Samuel D]

The classic Topeak Super Chain Tool is not very expensive and has a strong chain tool capable of pushing pins in as well as out. Importantly, it has a 5 mm and 6 mm Allen key built in. In combination with a couple of smaller Allen keys chosen for my particular bicycle, I found that this approach resulted in less weight (and better function) than any of the otherwise good multi-tools on the market.

More details elsewhere for tool nerds. (Looking at those pictures, I remember when everything was crisp and clean. Now it’s all a mess, the tin is battered, and my underwear rag is mostly used up. But the carefully planned kit has worked great!)

[mattc]

Thanks Samuel; that is a thread that I knew must exist somewhere in the world of CTC, but I hadn't seen it before. It's also a rabbit warren .... 

[KM]

I carry the same kit on my ‘Audax’ bike regardless of how far I’m going. Usual stuff including quicklinks, small roll of electrician’s tape, zip ties. And folding Gatorskin, brake and gear cable, spare rear mech hanger. I also leave a rear light on my underseat pack loop. That way I know where everything is and I avoid the faff of scrabbling around for stuff whenever it’s needed.

[ElyDave]

I carry the same kit on my ‘Audax’ bike regardless of how far I’m going. Usual stuff including quicklinks, small roll of electrician’s tape, zip ties. And folding Gatorskin, brake and gear cable, spare rear mech hanger. I also leave a rear light on my underseat pack loop. That way I know where everything is and I avoid the faff of scrabbling around for stuff whenever it’s needed.

+1, all my stuff just stays in the rack bag, organised in plastic bags for ease of finding when required.

As for GP4000 sidewall failures I'd like to see stats, I've ridden those for years with no undue issues

[Paul H]

I'm trying to work out how bummed out I'd be if I had to scratch either because my tyre had failed to the point that it was unridable, vs the risk of such a failure.

I think this thread has changed the odds, having given it such consideration you're now going to feel so much worse in the unlikely event that you need one and haven't got it. Not just you, but everyone who suggested it wasn't necessary.
I've carried a friction down tube lever with a gear cable fitted for about 15 years, ever since a crash damaged Ergo meant a DNF, the one time I might have been useful I forgot I had it  

[Zed43]

So as others have suggested there are several factors that might push you towards carrying a spare;
1) that your tyres are a funny size that you would not be able to replace easily 650b
2) that your tyres are relatively flimsy and might easily fail Compass Extra Light
3) that you can carry a spare tyre easily (maybe as part of  kit shared between others) 20 liter randonneur bag
4) that a tyre failure on the road might be exceptionally inconvenient (eg because you are riding in the middle of the night, or far away from the shops, or backup help/transport) yes, yes and yes
5) that you are riding on roads that are more than averagely likely to trash you tyres yes

With hindsight it would have been prudent to take a spare when riding TinaT  (I blame youthful optimism and a history of never having a serious failure)

Never leave without a few feet of ductape wrapped around the pump though, and a £5 note would do as an improvised tyre boot.

[Frank9755]

As for GP4000 sidewall failures I'd like to see stats, I've ridden those for years with no undue issues

You're not going to see 'stats'. Who would compile and publish them? Continental? Unlikely.

Who knows about my failure at Nullarbor? A few friends, dotwatchers and people who read cycling forums: I didn't tell Continental. As with all these things, a reputation is acquired, sometimes rightly, sometimes wrongly.

But, thinking statistically for a second, let's assume that the average rate for tyre sidewall failure within 5000 km of riding is 1 in 10,000. That's a complete guess with no basis. What rate would a particular model need to have to become known for having a tendency to blow?

If it was 1 in 2, that would be massively worse than average. A GP 4000 user could expect they would have one good tyre and one bad. Although some, 25%, would be lucky and get two good tyres and not see what the fuss was about.

If it was 1 in 200, that would still be 50 times worse than average and sounds like clear evidence of a problem. But the chances for any given rider of getting a dud would only be 1%.  Buy a new set every year for 10 years and you still have a 90% chance of not having a blowout.

The point is that your happy experience of no failures is not inconsistent with there actually being an issue. But they are nice tyres when intact, so long may your good luck continue!

[BeMoreMike]

I've recently started carrying an extra tyre on all Audax's and anything where i'm beyond a rescue call, a 25mm folder cable ties nicely into the space behind the top of my seat tube and stays.
Having recently slimmed down a few kilos of timber and seen my own flabby spare tyre shrink somewhat, offsetting a few hundred grams with emergency spares seems sensible.

As for other more unusual spares, i once got myself out of a pickle and saved a good few quids when camping touring up the west coast of Scotland by having a replacement derailleur sent from home to a Post Office in a village i knew id be passing through the next day, using the Local Collect service.