Light and easy to install, the popular Gamut single ring chain device offers the perfect method of ensuring your chain never falls off.
Single chainring drivetrains (dubbed 1 x 10 by the Bike Industry’s Dept Of Unnecessary New Jargon) are all the rage this year so we're seeing more and more riders, even lightweight cross-country types, seeking out decent chain devices.
When you ditch your double or triple rings, and strip away the front mech, you need something to keep the chain on. As a result chainguides are enjoying a surge in popularity, beyond their previous niche of downhill racing use.
Gamut is one of the more recognisable names, and is a popular choice with downhill racers and riders.
The Gamut P30 has been designed to be light weight and specifically to work with a 36-tooth chain ring. The specificity of its design allows every part to be as minimal as possible, keeping weight down.
Out of the box it's easy to install. The slim sheet of instructions are obvious and easy to follow, which is just as well as I fitted it the morning before rushing off to the Alps for Megavalanche.
Fitting is simply a case of removing the chainset, and pulling the chain rings off. Then you install the exquisitely machined Gamut 36-tooth ring, ‘boomerang’ with roller and guide and polycarbonate bashguard.
All plain sailing, right? Well, not quite. Gamut don't supply any chain ring bolts; they expect you to use the ones on your chainset.
This will be fine with most cranks, but we attempted to fit it to a Shimano XTR chainset. Shimano uses its own bolts in the XTR chainset and they’re not compatible with the Gamut.
After some scrabbling around in the tool box we plundered another chainset for its chainring bolts. Problem solved, but it wouldn't have been a problem if Gamut had supplied some bolts. Given how variable chainset designs are becoming, that’d be a sensible precaution.
Gamut has built in a sensible amount adjustment so you can fine-tune the fit. The boomerang fits to ISCG05 mounts and you can rotate it to get the lower roller in the optimum position. There’s a bag of spacer washers in the pack do you can get everything correctly spaced out. The Gamut uses a smooth nylon pulley, riding on two sealed cartridge bearings, with lips either side to retain the chain. Nice.
On the trail
Once the cranks had been reinstalled and everything tightened up, it was off to the Alps to test it. I was immediately clear why Gamut devices are so popular with both professional and amateur riders: the chain never falls off.
We tried our best to get it to dismount but the combination of the lower roller, top guide and bashguard kept the chain securely in place. It's rock solid.
The bashguard may be light but it's shrugged off more than its share of impacts in a week of riding, and hasn't been bent out of shape yet. The boomerang is just as robust.
You can detect a shade of resistance when riding but it's not a significant; certainly not enough to worry about.
Our only complaint about the P30 once it’s on the bike is that it’s noisy particularly in the lower gears when you’re pedalling up climbs and to the lift station.
It's noisy because the chain rides up and over the lower roller, and there seems to be no way to adjust it. We placed the roller as low as the boomerang would allow to smooth out the chain’s path, but still it made a racket.
Fortunately, it’s much less noticeable when you’re properly underway. Once you’re in higher gears, and especially descending, you never notice it.
Weight is impressive, at just 242g for the lot. If you're fitting it to a trail bike but are worried about adding too much weight, the Gamut doesn't offend.
A light and durable chain guide that is perfect for trail bikes.
Main website: www.gamutusa.com
UK supplier: Madison Cycles