FRM´s new 29er rims – XMD 388

Editor’s Note: This report comes from our European Contributor- “c_g” and we thank him for his efforts in getting this information and conducting this review/test.

I have just taken delivery of the new 29er FRM tubeless ready rims called “XMD 388 29er“ right from the very first production run (plus tubeless accessories).

These rims are yet another product by highly innovative “think tank” company FRM bicycles, based in Italy and Germany.

For years FRM has been successful at ultra light bikes and bike components for road and off-road racing. Their portfolio ranges from their own cranksets (double and triple, with FR & DH cranks just released), suspension and rigid forks, stems, bars, hubs, disc brakes, seatposts, seats, ultralight clincher and also new the lightest tubular MTB rims / wheels … basically they offer most everything to make your bike lighter (and hopefully faster).

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For a full view of their products see: www.frmbike.de (it helps if you know German, Italian French, or Dutch for the English site is currently under construction)

If in the US you have never heard about FRM bicycles – it is because they are small “insider” company well recognized by European racing professionals. Basically they are so involved in new product development projects, trend scouting and improving their products that they put little effort into advertisement or marketing. FRM Germany´s head Boris Latsch is a multi tasking workaholic, always handling various projects simultaneously, seeking perfected perfection – and their products show it. So it is also with Franco Ricci Mingani, the head and mind of FRM Italy. Expect to see some more really cool products from them in the near future (I will keep you updated).

FRM has always had a keen eye on the tubeless movement and they were the first to bring tubeless ready rims to the European market where only Mavic´s UST was known until then. They introduced and distributed NOTUBES back in the 1990s. For about 2 years now FRM has been selling their first own design of tubeless ready rims, the XMD 333 for 26er, with very good success – true 318 to 335 gm including eyelets!

Now, to serve the more budget conscious racers and heavier riders the XMD 388 was introduced. It shares the same design traits as the XMD 333 but with sleeved joints and slightly increased wall thickness (resulting in a remarkable ~380 gm including eyelets at 26´ or 410-420 gm for 29er). The added material should also create a stiffer rim and push the rims´ capacity more into a light All Mountain range.

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For me the eyelets are a nice addition and it makes me believe that stress from spokes gets dissipated more evenly over a larger area, minimizing long term fatigue, but the benefits might be argued as arbitrary. Looking over the multitude of rim designs you see eyelets as often as not without being limited to the weight weenie fraction.

With this rim XMD388 FRM is giving 29ers another chance. Some Euro riders among you might remember this rims predecessor derived from the ultralight XMD 333, but like it can happen to innovative products – they simply might be too early. So it was with FRM´s first 29er rims- for most European riders considered the 29ers trekking bikes with larger tires … shame on us!!

My set of rims weighed 418 and 422 g. They measured exactly 24.6 mm (outside) and 19 mm inside width. ERD, or for the less technical ones – the inside diameter of the rims for determining spoke length, is at 602 mm with 32 hole spoke drillings available. These numbers are fairly standard for lightweight cross country oriented rims so I am expecting no big surprises there. Recommended tire width is 1,75 to 2,3 – again nothing unusual. Like all FRM rims, apart from the tubulars of course, they feature a tubeless specific cross section and bead construction.

From my past experiences with FRM rims I am expecting a positively strong bead/rim interface. The high and almost level “inside shoulders” are to provide a tight and burp free seal down to the lowest pressures. (but keep in mind these features vary strongly from tire to tire – my suggestion: always use tubeless ready tires for best results!)

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In contrast to its tubeless ready competitors with comparable dimensions the XMD 388 is designed with an asymmetrical cross section allowing both for equal length spokes on drive and non-drive side and higher spoke tension. This asymmetry is especially apparent with the spoke drillings on the inside cavity. Smoothing the very sharp edges on these drill holes are the only indication on the rims that even perfectionists can´t control everything. Once the tape is installed all is concealed and therefore remains a minor complaint.

There still is a weight limit on the XMD 388 of 90 kg for the 29er rims (100 kg for 26´´) but it can safely be considered conservative. (I have ridden the XMD 333 prototypes at 315 g for a long time and they held up well to my 85 kg and more rigid riding.)

Having learned from some riders who were using the first line of 29er rims as training rims with road tires and roadie like pressures – there is a 4 bar maximum pressure laser etched to the rim to avoid failure due to abuse.

Like other tubeless ready rims they accept a tubed setup or can be converted tubeless with a rim strip / sealing tape.

Apart from the rims themselves – one thing worth noting are the tubeless kits recommended with this rim. There is a 5m role of 21 mm width sealing tape (also available in 25 mm for wider rims) which has proven to be very strong and reliable. There are no Kevlar reinforcement worked into but the tape seems very resistant to any type of mistreatment and has no apparent stretch when mounted. Only when working overly hard with my steel mounting levers did I get to break the sealing tape but with a bit of caution this can easily be avoided. This FRM proprietary tape rim strips is called “White tape”, adds approximately 5 g per wheel and can be purchased separately.

The valve stems specified by FRM are the best there are – period. They are extremely reliable, seal very well with their wide base and resist rotation when tightened down by the screw. Of course they feature exchangeable valve cores and a easy to grip lock nut. Having used them for several tubeless wheelsets over the last years I have come to appreciate these little guys tremendously. (For those of you familiar with the Caffelatex valves stems – they are exactly the same.)

They have come to me as a huge improvement over the older round based versions by Notubes, which failed on me several times when tightening too hard.

The XMD 388 is offered in a fairly conservative matte black eloxal finish with cool looking laser etched logos and later on in a en-vogue powder coated white, which was not available in the first production run. By first inspection the finish looks like it would scratch easily but I will keep an eye out for this as the test progresses.

For those of you in favour of a colourful life – take a look at the XMD 333 line up and realize: There is hope for gold, red and blue also.

As a strong tubeless believer, this is the setup I will be running them

More to come when the build is finished and riding commences….”c_g”