2008 Mavic EX 823 and Mavic EX 721
Monday, February 4th, 2008
Mavic has been in the rim business for a long time. Inside we take a look at the EX 823 and the EX 721 rims that they offer. Mavic makes some of the best rims in the business and these two are no exception. Kyle over at Mavic helped in acquiring these rims for you guys to see all these details. Check them out inside.
Chances are if you already know about these rims, there’s not much more to say. They’re strong, work for the gravity enthused, and come in at a respectable weight. Both rims are available in 32 or 36 hole options. The Mavic EX 721 rim is a single eyelet rim that has a 21mm inner diameter. Its uses are almost endless and is perfect for dirt jumpers, downhillers, and freeriders. You can get the rim in either silver or black. It features Mavic’s Maxtal and SUP (a welded and milled rim joint). These rims are strong and are well proven in all those disciplines.
(click to enlarge)
The 823 has a similar song and dance to it and is also widely used. It is Mavic’s air tight tubeless downhill rim and is essentially bombproof. This is the same rim used in their Deemax wheelset. The rim, while a bit heavier than the 721, doesn’t need any rim strip tape or a tube. The tire bed is a little bit wider at 23mm. It’s meant to be ran with tubeless tires, but using some Stans No Tubes in combination with any DH tire works pretty well. You’ll be hard pressed to damage these rims. It features Maxtal and SUP like the 721, but also is UST compatible and has Mavic’s Fore technology which they say makes the rim 4 times stronger as only one wall of the rim is drilled. You can also still use a tube in a Mavic EX 823 without any problems.
(left) Mavic 823 (right) Mavic 721 (click to enlarge)
Since the EX 823 rim is tubeless, it has no holes in the tire bed. It uses nipple inserts which hold in the spoke nipples. They’re reverse threaded and you’ll need to run at least 14mm or 16mm nipples with these rims. Locktite is highly suggested when installing the nipple inserts to make sure they don’t come loose.
nipple inserts (click to enlarge)
If you’re planning on building up a set of these wheels, you’ll need to know the ERD (effective rim diameter). Some spoke calcualtors have the incorrect ERD so make sure you’ve got the right ERD in there and you’ve calculated for the proper nipple size as well.
- ERD for the EX 823 is 528
- ERD for the EX 721 is 532
While the 823 may seem like a lot heavier than the 721 rim, it does offer advantages if you’re running them tubeless. You won’t need a tube which will save you anywhere from ~200-600g per wheel which more than makes up for the small penalty of the increased rim weight in addition to a faster accelerating wheel, more traction, and a stronger rim since only one wall is drilled through.
(click to enlarge)
| Part | Year | Real(g) | Pic. |
|---|---|---|---|
| Mavic EX 721 32 hole rim | 2008 | 577 |  |
| Mavic EX 823 32 hole rim and Nipple Inserts | 2008 | 716 | |
| Mavic 823 UST valve core | 2008 | 5 | |
| Mavic EX 823 32 nipple inserts (necessary to function) | 2008 | 54 | |
| Mavic EX 823 32 hole rim (No nipple inserts) | 2008 | 662 | |
February 4th, 2008 at 4:05 pm
Dude - you read my mind!
I was surfing the web the other night for official weights for these rims!
Nice work Jason - finally we have answered the question that has plagued man since the dawn of time: what IS the weight of an 823???
=)
cK
February 4th, 2008 at 11:56 pm
i’ve never owned mavic stuff, but it seems tempting. still, 716 grams for a rim is damn hefty, i think the 721 is more tempting, at least to me. any chances of you checking out some of their lighter offerings in the future? it seems like wheels using rims like dt 5.1d and syncros ds28 rims are becoming more popular, does mavic have a comparable offering? i’ve heard about the en521, but i’m not so sure it’s up to par with the other rims.
February 5th, 2008 at 3:58 am
Nice one Jason! Finally some ACTUAL weights of the two popular Mavic setups. Zack as Jason mentions you need to take everything into account:
144g weight difference between the two rims [EX823 less EX721]
This ^^ may seem like a big weight penalty, but when you consider you can mount a UST tire directly onto the rim without need for sealant, rim strips etc it is the clear winner! Consider this for example:
EX721 rim: 577g
Stans DH Rim Strip: 147g
Stans Sealant: 30g
Maxxis Minion DHF 2.5″ 42a: 1330g
Total weight: 2084g
EX823 rim: 662g
EX823 spoke inserts: 54g
EX825 Valve Core: 5g
Maxxis Minion DHF 2.5″ 42a: 1270g
Total weight: 1991g
The EX823 wins by 93g per wheel! For a real, no-fuss UST setup with the benefits of a much sturdier rim. In the long-run its a far better setup.
February 5th, 2008 at 10:03 am
Yea, that pretty much sums it up. While there are other options, you’ll be hard pressed (even with a 5.1d rim) to come out vastly lower than an 823 setup tubeless.
Basically any rim you have to add ~200g at least for a XC tube. That in itself makes it very hard to compete with an 823 if you’re running tubeless.
I’d like to check out the en521 and others as well eventually.
February 5th, 2008 at 1:04 pm
Hi Andre
Why did you use “Stans DH Rim Strip” with the EX721 ?
A “Stans FR Rim Strip” is lighter and enough large
With that the difference is 11g only
And i thing we can use a lighter strip
February 5th, 2008 at 3:11 pm
For the EX721, you use the Rhyno Light rim strip if you’re looking at the Stans options. You can add up the numbers, its still pretty negligible. Additionally Stans tubeless conversions work best with at least 1 strip of Velox rim strip tape to seal better.
February 5th, 2008 at 9:57 pm
ghetto tubeless keeps it pretty light also. another thing i was thinking of is that more than a couple people use stans in their already tubeless setups to compensate for the thinner UST sidewalls should there be a little tear. when you factor that in, there really isn’t much of a difference between the two.
February 6th, 2008 at 2:40 am
Personally I wouldn’t bother using Stans in a UST setup on the DH bike. Generally speaking if you flat a UST tire in a DH scenario its going flat regardless of what sealant you have in.
February 6th, 2008 at 11:29 am
I use 823 for nearly a year now. I beat the hell out of them. Came down flat - no problem. Landed on flat when I missed transition from 3 meters high. No problem. I’m ~ 85kgs. Definitely a best buy.
February 6th, 2008 at 2:31 pm
a UST 823 is basically the same weight as a tubeless 721. there is no significant difference:
721 rim: 580g
Velox: 18g
Stans rhyno lite rim strip: 56g
Maxxis UST 2.5 Minion DHF: 1270g
1 scoop stans: 60g
Total: 1984g
which is the same as the 823 setup above.
using a UST tire on a stan conversion is nice as it seals immediately and is lighter due to the bead.
823 “seems” stronger but 721 has more setup and tire options
February 6th, 2008 at 4:01 pm
Yea the 721 will give you more options. I still feel that the 823 is a bit stronger (i’ve yet to see them dent really where as i’ve seen a handful of 721’s dent).
721 is a solid bet, but for out of the box tubeless compatibility and ease of setup the 823 if you’re running tubeless 100% of the time, it makes sense.
721 though does indeed have more options which I do like as well.
Part of the fun in spec’ing a bike is picking all the parts. Both options are solid in my opinion.
February 7th, 2008 at 2:00 am
That’s interesting that the new 823’s weigh 716 with the threaded cups because I weighed my earlier (2005) 823’s with the cups (36h) and it came out to 654g. So they’ve seriously beefed up the newer versions as they’re 75g heavier now.
February 7th, 2008 at 11:32 am
If the 823 stronger since it isn’t drilled, Mavic could take some weight off by making it strong as the 721
February 7th, 2008 at 12:15 pm
The older 823 rims were not built nearly as strong.
I think the 823 too could loose some weight (or make an 821 rim) but i don’t think Mavic wants to sacrifice any strength as the old 2005 823’s were breaking (they had a channel on the rim as well that possibly aided in this.) The newer 823’s are borderline overbuilt.
February 8th, 2008 at 6:04 am
Great article. But for me the debate is whether to go tubeless at all. I think it was MBR (UK mag) in the World Champs issue that asked a number of top DH pros whether they were running tubed or tubeless…all were running tubes. WHY?
I’m guessing tubeless has a disadvantage in sidewall stiffness / cornering traction.
Sorry to hijack the thread…
February 8th, 2008 at 10:15 am
Aaron, there’s a lot of misconceptions about tubeless that seem to perpetuate but there are a lot of valid reasons not to go tubeless as well. Tubeless is plenty stiff / and has ample cornering traction when compared to a tube variant.
There are some setbacks to tubeless including the an initial greater amount of tire psi and the need for an air compressor sometimes to ease installation and bead seating.
Second, tubes typically always work no matter if your rim has a dent in it. A tubeless rim needs the seal in tact. Additionally it is possible to roll a tire off depending on psi/circumstances.
Third, Sponsors.
Fourth, misconception of lower weight - I think lots of people love thinking the 823 will accelerate slower than some other combinations since the rim is heavier. However once you add the weight of a tube in most rims (there are exceptions) there will be more weight on the extremities of the bike where it affects the bikes snappyness more since the tube is further out than a rim would be.
Fifth - Tire changes/choices are not always easy, a tubed wheel doesn’t need any stans to work and can argueably be changed out quicker.
Sixth - time. Time is of the essence if you’ve got no mechanic. Its a lot easier to change a tube in most cases.
Seventh - money. Face it, tubeless rims aren’t cheap. If you constantly are banging your equipment, you may need disposable parts to keep it running in tip top condition. Rebuilding a tubeless wheel takes a bit more time.
Eighth - i’m sure there’s some others i’ve missed but there are more.
There are a lot of people (pros and joe’s) running tubeless. There are kits availble to convert just about every rim out there. In addition, you can make your own setup as well with an old tube for practically nothing.
February 8th, 2008 at 8:59 pm
if you’ve had problems with denting rims, try the 823 even if you don’t want to run tubeless. the extra non-drilled wall deffinetly makes a difference.
February 9th, 2008 at 3:19 am
I’m a bit surprise by the diameter of the rims 532 mm for the EX721 and 528 mm for the EX823. DT swiss in there spoke calculator says 532 mm for the EX823 and 537 mm for the EX721.
I need to make 2 wheels; 1 with an EX721 and one with an EX823; What th truth ?
if anybody say, thanks a lot
February 9th, 2008 at 11:18 am
ph, those are the numbers mavic gave me. I do know the erd for the 823 on the dtswiss site is incorrect (lists the old 2005ERD). You can also call them to verify, or measure the rims yourself as well.
February 10th, 2008 at 2:26 pm
Very much needed information there thanks.
Now I just have to figure out which one is for me. Im not very smooth, so I ride sometimes pretty hard against rocks and roots. Would it be better to go with 823´s or 721´s? Of course I Iike it lighter, but is 823 worth the cost? I ride Michelin, so the tires are already tubeless.
February 12th, 2008 at 1:10 pm
Thanks a lot I think that the DT information are wrong because they say X823 or D3.1: the old profile of the rims but i’ve had no confirmation.
To says some thing, I ride in DH since 10 years; i ride tubeless since the beginning of them 2003 and I can see only advantages for this:
Weight 300g for one maxxis dh tube; 600 g for two !
Simplicity: one tire and OK no problem to mounting the tube
Strong: the new 823 (since 2005) are the strongest rim i’ve ever had.
after You must like it to ride tubeless!
February 16th, 2008 at 2:04 pm
Inner rim widths for these rims are 21mm & 23mm respectively.
Do you have an outer rim width for both of these rims ?
Thanks!
February 16th, 2008 at 9:51 pm
I think ERDs depends on who make the reading. Following Roger Musson’s wheelbuilding book.
my 721’s ERD was measured 535mm. After putting the wheels together I them for final truing at my local shop and they were amazed on how they came.
I’m building a wheelset on 823s and won’t buy spokes until making my ERD measurement.
February 16th, 2008 at 10:33 pm
There is some leeway in measuring the ERD as you can accommodate for minute differences in the calculator as you will have slightly longer/shorter spokes. If the number is too far off however, you’re going to be in a mess.
Measuring yourself has its benefits but i’ve built with these numbers and its turned out just dandy as well.
February 21st, 2008 at 12:38 am
I’ve been looking to give tubeless a try and was looking pretty hard at the 823’s w/Kings or I9’s. Main reason was for weight and to run lower tire psi without pinch flats…that being said…I was talking with a friend tonight and he was saying that in the BayArea a lot of people who run tubeless are now running a tube along with the setup just in case they flat…have you guys ever heard of such a thing??? Seems like it negates the weight savings aspect.
February 21st, 2008 at 12:41 am
Lowball - never heard of people really running tubes in conjunction with a tubeless setup. I have however heard of people with tubeless carrying a spare tube in case they puncture/flat.
Running a bit of sealant (Stans No-tubes) can help alleviate any small punctures and what not.
Running a tube in an 823 setup would indeed negate the point of running tubeless and the weight savings attributed to running tubeless.
June 30th, 2008 at 9:59 am
Instead of running tubeless to allow low pressures, try running tubeless at or just below normal pressures and notice how you still get better traction. You might get away with lower, but running a lot lower than that is usually not going to be fast and it opens you up to all kinds of problems like burping, sidewall tears and pinching through the tire casing.