On hearing the price of these inner tubes from Swiss company Eclipse, the standard reaction is surprise followed up by mild indignation that anyone would dare to charge 10 times as much as they would for normal inner tubes.
However, at just 61g for one of the 29x1.5-2.25in tubes we tested, they are substantially lighter. Replacing our standard tubes instantly removed 322g (0.7lb) of all-important rotating weight.
Getting rid of that mass sat right out at the edge of the wheel has a profound effect on the amount of effort it takes to accelerate them up to speed and change direction – and that’s even more prominent if you’re on a big-wheeler.
Within a few pedal strokes, the change was immediately obvious, with a much perkier feel to the bike. This goes some way to making these tubes look cost effective too; upgrading to a 300g lighter wheelset will cost you significantly more than this, and super-lightweight tyres are both expensive and fragile.
Of course, there are other ways of getting rid of rotating weight and most tubeless conversion kits are cheaper. The weight saving from tubeless is less substantial however, especially once you have around 50ml of sealant sloshing about in your tyres.
Also, if you’re a regular rubber changer then messing about with sealant can be both tiresome and messy, and running low pressures can lead to regular tyre burping. On the flipside, running sealant does offer protectection against thorns and minor tyre cuts.
These tubes held air as well as normal tubes and pinch puncture resistance, amazingly, is just as good or better. Our sister mag MBUK ran a set through a puncture-plagued gravity enduro round without any issues, despite using them in lightweight tyres.
One of the four tubes we had on test did split by the valve, though UK distributor Silverfish put that down to a faulty batch and quickly replaced it. We haven’t had any trouble since then.
As for longevity, we’ve only had a flat once from a thorn, and that was easily and effectively fixed using the special self-adhesive Eclipse patches, available separately.
This article was originally published in What Mountain Bike magazine, available on Apple Newsstand and Zinio.