I picked up a used wheelset not knowing what I was getting. Matrix ISO tubular rims made by Trek. These are wicked light at 285 grams each. Almost too light to believe.

I've heard of Fiamme Ergels being this light and people not trusting to use them unless lightweights (since they were intended by lightweights for race days).

Any safety concerns about a 215-pound rider attempting to use these rims? I've read they came standard on Trek's higher-end racing bikes, which makes me believe that they've got to be safe-to-ride for my weight (assuming no existing cracks of course).

How many spokes?

I am riding on GEL 280s right now. Front wheel only. 28 spoke, although 32 would be better. I am a few stone lighter than you.

Maybe these rims could be used in front wheels, if 32s or 36 spoke versions. If the nipple holes aren't cracked, as these rims were prone to.

Rear wheels - this is a much more demanding application, as 60+% of your weight is on the rear, the rear takes the biggest impacts, and the rim has to deal with uneven spoke tension differentials due to dishing.

Even a lightweight may not be able to use these light rims on the rear. Rims have been getting real porky these days due to:
- Clinchers. But then clincher rims are heavy, fragile and just plain suck. But we're talking superior tubular technology here...
- The increasingly challenging dishing requirements of rear wheels. On 11-speed wheels, drive side spokes are more than double the tension of the non-drive. This makes really light rims infeasible, as you get a wavy pattern on the braking surface once you tighten up the spokes.

Back in the late 80's I worked at what was then one of the largest Trek dealers in CA. We had several stacks of ISO rims in both tubular and clincher. We used them for all of our custom wheel builds. Totally bomb proof. Are yours NOS, or have they already been used? I am always wary about using rims of unknown history.

For the record, I used a set of 32 hole ISO clinchers at the 2014 L'Eroica and the 2015 L'Eroica California with no problems, and I am at 180 pounds. That wheelset is built around a 126mm rear hub, though. Like the above posters mentioned, dishing problems may be an issue if you are going with a modern hubset.

I don't remember Matrix Iso rims as being especially light. It was their aero shape and hard-anodizing that was promoted above their being lightweight, at least as I recall. I know there are several different models of Matrix ISO rims. Which version do you have? Are you sure about the measurement?

That said, the wheels are probably going to be okay, but not recommended for everyday/city riding. I weigh ~195-lb and ride on a GL330 front wheel (32-hole) without any problems. I used the same wheel when I weighed closer to 225-lbs and it didn't explode. Much of it has to do with the # of spokes and the quality of the wheelbuilder. Also important is how hard you ride over bumps and potholes. Some people are better as absorbing the road so their equipment doesn't have to. For your weight, less than 32 spokes and fewer than 3-cross lacing with GL 280s is probably asking for trouble.

Thanks folks. They are used, but show little wear. I noticed they are built without spoke washers, so seems like a rebuild with spoke washers would be in order. The front is 24 spokes. The rear is 32 spokes.

I'm not actually sure they are 285 grams. I Googled "Matrix ISO tubular" and found something that said 285 grams. But I just found some spreadsheet on some "weightweanies" website that says they are 410 grams (which is more reasonable!).

I've got a set of these NOS as a birthday gift from the shop I worked at last year as they've been a Trek dealer for quite some time. The owner just gave them to me because they were sitting in basement for quite a few years. Basically no braking surface as they're completely angled. I almost thought they were track tubular rims from the way they looked. I think my pair are 32/36.

I think you're likely right about the weight. I dug a little more, too. There are more than one version of the Matrix Iso rim. I couldn't find a catalog (though I'm sure one is out there), but did find another mention of 285g weight. I had a front Matrix Iso on my TT bike long ago--not a lot of braking. They came in clincher versions, too, which may be the 410g measurement.

Do you use them?

Yeah, completely angled braking surface. Just like my other tubular rims (Fiamme Hard Silver).

They were followed by the ISO-II.
They are great wheels.
I have no idea about weight being an issue.

Pair them with some 7400 hubs and you'll have wheels that will perform with any modern wheels at 1/3 the price.
Just lace them right, make sure they're trued and tensioned.

The Fiammes were infamous for getting out of round after use, and hard to get back to shape.
May racers tossed them after a few rides. I know folks who've been riding them for years, no issues.

Originally the Matrix tubular rims were shipped with washers. Because of the narrow channel inside the rim, they were rectangular rather than round:



Later, the washers were no longer deemed necessary.

I have several NOS unlaced Matrix tubular rims I use for stretching tires (they were rejected for defective anodizing). I should scare up a scale and weigh one...

After my accident in 2009, I picked up a Colnago with Mavic 501 hubs and GL330 rims. They are well used with the ano nearly gone near the spokes, typical. They are 32 hole and at the time, I weighed near 210-220. I did have a spoke failure but found the tension to be off on the rest of the spokes and a mix of both DB and straight ga. I fixed both and have not had an issue since. The configuration is 126 spacing with 7 spd. A local recycle bicycle shop had a pair of NOS GL330 that I picked up for the cost of a low end tubular tire. I use them to stretch tubulars until I figure out what I am going to do with them. I may be on the edge of the envelope with them but after a couple thousand miles, I am not worried.

I'd ride those Matrix and not worry about it, though tire width and pressure for the terrain might be something to consider.

Curious, was there at a time a connection between Sun USA and Trek Matrix? For a light road application tubular rim, had great luck with Sun. I don't exactly recall, but the anodized Suns were the exact profile to the Matrix. Was in a hurry, think to have done some rear wheel swap and not wanting to pull the tubulars, swap cogset, etc. for a ride. If not for the decals, they looked like a perfect match.

I do use a pair of Matrix 36 hole clincher (ISO-2C) on an RRB (126mm spaced / 6 speed). A little compromise in weight but damn robust. The bike is used everywhere including gravel, off-road trails. I've hit some chuck holes and other during night rides street and in the woods. With never enough lighting, they catch me off-guard and then I don't have my timing right to unweight. Tire choice is Tufo tubular/clincher. Its possible this tire design takes the punishment load off the clincher rim.

(Tufo t/c on Matrix ISO2C depicted bottom of image)

Never used laced them up yet and have just been sitting around my shed and now packed away to travel cross country this weekend. I've been wanting to build them up but finding the right hubs to lace them up with. I picked up some NOS Performance MT21 tubular rims for dirt cheap from Ben's Cyclery on eBay still in the Performance bag for $24 shipped. They must of bought a stockpile of these out from Performance because they've been selling these for awhile and for 24 bucks shipped and I can't picture them making too much on these. These are getting laced up with my sealed Record high flange hubs and should be a decent relatively lighter wheels.

You may have a point there, Scott. The Sun M14-A was another wheel that was very close to a Matrix wheel, and it was a "standard" for a lot of builders. Or, perhaps what works, works, as the Mavic Profil tubulars were very similar to the ISO's. I think I read here that ISO referred to Isosceles.

Mavic made "Profil" tubular rims? I thought those were just Wolbers...... cause I have Wolber Profil 20's on one of my wheelsets. Pretty deep aero section for their time, and even with mine just 28 spokes, they built up to be very stiff, strong and rigid.....