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P45 that big chain ring! Gamut P30 review

by Phil on 4th December 2009

It's a good while since I bolted this device onto my bike but due to distractions from the hardtail, it has seen very little action since last autumn. Things have changed in the last couple of months and I've been out, avidly hanging up jumps, casing landings, riding DH and hucking the 4X to flat - all in the name of product testing.
I can hardly believe that 2009 is my 20th year of racing push bikes. I started DH in the mid 90's and progressed from there. Three things stick in my mind from bikes of the mid to late 90's - massive chainrings, constantly losing your chain and lots of punctures!

These days, thankfully, things have moved on massively. One of the simple advances that it's easy to take for granted relates to chain devices. Most of them just work now, especially if you pay attention to the setup. No more jamming sticks in there or hitting them with a rock to keep your chain on that 44 tooth chainring.

Speaking of big chainrings, it's pretty accepted that unless you are on the Kamikazee, these days 40T is more than enough for DH, especially in the UK. 36T seems to be a perfect size for me on my hardtail and that's where the Gamut P30 comes in. Anyone running over a 40T chainring on a hardtail needs to P45* that sucker and get with the program!

Speaking of getting with the program, Gamut have a big range of chain devices, with something to suit most setups. They offer the P20, P30 and P40 for different size chainrings, as well as some recently released twin ring systems.

This chain device uses the classic 'boomerang/bashring' combo design and comes in a range of sizes and mounting options so make sure you choose the right one for your application. Once you know what size ring you are going to be running, check your frame as BB, ISCG and ISCG '05 options are all available, but specific to the backplate with the version you buy, so not interchangeable.

The P30 takes a maximum 36 tooth ring and is perfect for 4X/BMX track duties when paired with a road block, so it got bolted onto my Absolut 4X.


Where the Gamut differs from other devices I've used is the simplicity. Sticking with tried and tested principles, they've focussed on refining the setup and saving weight. Constructed from a light weight back plate, outer bash and plastic hardware, the device certainly is featherweight.

Weight comparrison:
e13 SRS - 454g**
e13 LG1 - 296g
Gamut P30 - 208g

(**note: the e13 SGS weighed here featured a custom bashguard, turned down in size to save weight and suit a 36T chainring, therefore equivalent to the P30.)

Since there are numerous frame designs and setups, different cranks and chainlines to accommodate, setup is key to good performance of any chain device. The Gamut is no different - fortunately, setting it up was a treat.

The ISCG holes bolted the back plate straight onto my frame without an adaptor.


The top guide is spaced off the backplate pretty easily. X-type cranks make this a breeze as you can slide the drive side on, check the clearance and whip it off it if you need to tweak. Simple.

The lower roller can be adjusted sideways by loosening the locknut on the back of the boomerang and adjusting the hex bolt before tightening back up again.

After intial setup I noticed the lower roller bolt was very close to my back tyre. Rotating the backplate anti-clockwise brought the top guide into a better position and moved the roller down and forward, away from the tyre. However, some full sus designs or a larger rear block might need you to rotate the backplate clockwise and this could put the nut near the back tyre. Only a small point but streamlining this nut is the one possible improvement I could make.


So far, I've yet to suffer a single problem with the chain device despite my best attempts to derail the chain with hook ups, cases and slams at the Bolehills BMX track and some rough rattly hardtail DH sessions. Retention abilities are working out a treat! What's good enough for Mr. Minnaar seems to work for me too.

The only thing I've not tested is the durability of the bashguard. It's a tough material but is also very rigid. Since this is a compact device, fitted to my hardtail, this isn't an issue but hopefully the polycarbonate will take the 'bottom-out-onto-rocks' style hits my DH bike is usually subjected to!


After all that writing, the quick summary - the Gamut P30 is a simple, extremely light and very effective. This is a serious chain device and well worth checking out.

For more details, check out www.gamutusa.com
The UK Importers are www.madison.co.uk

* For the non-UK readers, the 'P45' is a form you get from your employer on your last day!

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