Mountain Bike Reviews Forum banner
1 - 7 of 7 Posts

· Registered
1,050 Posts
Discussion Starter · #1 ·
I have a set of new MAVIC EX823 Tubeless Rims and a new Saint 135x10 rear hub.(both 36holes)

So now I want to lace and build a rear wheel. I used the spokecalc, but the values for the Mavic EX823 seem to be incorrect (could also be the values for the Saint hub).
I know that something is incorrect I calculated and bought 252mm and 254mm spokes(left+right side) and 16mm alloy nipples and tried to build the wheel.

Didn´t work.
The spokes were too short, with quite some effort I could screw them in about 2 or 3 turns, while the FORE nipples where turned almost totally loose.
The thread of the spokes where visible. Tightening them anymore or trueing them would result in exploding alloy nipples or damaged alloy nipple threads :thumbsup: (or actually did result in...bang/ding sounds)

(I knew that it wouldn´t work, but tried it anyway, you know how that is ;) )

So I am about to order 256mm(freehub side) and 258mm(disc brake side) DT competition 2.0/1.8 spokes and 16mm brass nipples (alloy nipples suck).
I tried to measure the ERD and the hub and whatsoever, but I don´t have too fancy tools, in the end my measurements and selfmade calculations won´t be too accurate.
Therefore I just guesstimate, that the additional 4mm on the "to be bought" spokes will be sufficient. ?!?!

I read a nice book about wheel building, I am patient and really want to learn to do it, I am also not too bad in mechanical things, but the FORE nipples and UST stuff is driving me nuts :madman:

Please share your experiences with the EX823 or Tubeless rims. Or help me decide if the 256/258 guess could be right.

greetings and thanks for reading this novel (written in bad, german English)


· Registered
382 Posts
How many spoke crossings are you using, 3 or 4? As far as ERD of the rim I would double check it. I have the early style EX823's and I measured the ERD at 532mm. The newer rim is different than the one I have so I don't know if the ERD is the same. You can use a two spokes and nipples to measure the ERD, thead the nipple on all the way with some Loctite and cut the J bend of so they are the exact same length.

· I live to bike
2,462 Posts
using spocalc, I come up with 254.4 left, 253.1 right for 3cross. So 254 left, 253 right. It gives an ERD of 534.5. If worried about it, can probably get away with 1 mm longer. I'm guessing you will find 256 right, 258 left to be too long--you'll get the spokes threaded all the way in the nipple, but won't have enough tension on the wheel.

· Registered
49 Posts
I thought I'd share my experiences so far with the EX823 rim. I'm not absolutely sure what model year they are, but I just bought them (November 2008), and they have the same decals as those showcased here:

I measured the ERD myself, and it is 530mm. I took 6 measurements between 2 rims and the average was 530.0016 with deviations mostly between +0.20mm and -0.02mm and one at -0.40mm.

To take the measurements I used two 240mm lengths of spoke with the bend cut off, threaded (approximately 1/4 turn past hand tight to keep them from unscrewing) into DT 16mm nipples . There were between 9 and 10mm of thread on the spokes, and when screwed into the nipples they bottomed out just as the tips became flush with the bottom of the notch in the top of the nipple--exactly like the nipple in the top of this illustration:

While searching Ridemonkey, I found the following excerpt from Roger Musson's book Wheelbuilding, 4th ed. ( :
Spokes are generally manufactured in 1mm increments but many stores only stock even sizes, and some spokes are only made in 2mm increments. When using the spoke length calculator I always treat the resulting spoke sizes as maximums, there are however other considerations and this relates to the length of nipple used.

My spoke length calculator aims to calculate a spoke length such that the threaded end of the spoke lies flush with the bottom of the slot in the nipple - about 1mm below the top surface of the nipple. Rounding the spoke length up or down is based on the size of the nipple being used.

The following discussion is applicable to DT spokes; I'm not sure if the same applies to other brands.

For illustration purposes I've produced some cross sections of 16, 14, and 12mm DT nipples shown in Figure 59. The ruler at the top is in 1mm increments. All the nipples were gently screwed down until the threads bottomed out. Once the threads bottom out the nipple becomes tighter to turn, it will easily tighten with the wrench but the spoke will be deforming the threads in the nipple and whilst generally okay I always try to avoid this by selecting the correct length spoke.

12mm nipples

This is the most common size and accounts for the vast majority of wheels I build. The only time I use something longer is on the Mavic UST rims where a longer nipple is required due to the special eyelet design (Mavic recommend 16mm but I use 14mm).

When using 12mm nipples my ideal length is when the spoke is flush with the bottom of the slot in the nipple which is about 1mm below the top surface of the nipple (this is the length given by the spoke calculator). As you can see from the photo the spoke can easily screw through an extra 2mm (1mm above the top surface) so for spoke length purposes there is plenty of leeway in selecting a suitable length. With the ideal length at the bottom of the nipple slot you can go +/- 1mm. You could go +2mm but you will encounter the nipple bottoming out (emphasis mine - Stan). I wouldn't go -2mm because you are getting too low a thread engagement and also the shorter spokes will be more problematic when lacing/tensioning because you will be getting tight spokes too early in the build process unless you modify your nipple driver accordingly.

For example if using standard 12mm nipples and I calculated 264.6mm it would be okay to go with 265 or 264 but with a calculated 264.5 I'd be going with 264 but with the 12mm nipple it's not critical.

14mm nipples

The spoke in the bottomed out nipple lies flush with the top surface of the nipple. The spoke calculator will provide a length to the bottom of the nipple slot so you must subtract 1mm to give the ideal length which gives the option of then selecting spokes in the range plus/minus 1mm without fear of encountering the nipple bottoming out.

16mm nipples

The spoke in the bottomed out nipple lies flush with the bottom of the nipple slot so this is the absolute maximum length - do not go longer. This would be the length that the spoke calculator gives you so you need to modify this length by subtracting 2mm to give the ideal length with the option of then selecting spokes in the range plus/minus 1mm.

The DT Swiss spoke length calculator automatically subtracts 4mm if you specify a 16mm nipple and subtracts 2mm if you specify a 14mm nipple, both of which I find excessive compensations.
So, as I understand it, if a spoke calculator gives me a length of 253mm and I am using 16mm DT nipples, that is the longest length of spoke that will fit in this application without risk of damaging the spoke or nipple threads, since the spoke length given by the calculators is based on the assertion that the spoke will reach its optimal tension just as the tip becomes flush with the bottom of the groove in the top of the nipple, which happens to be the limit to which you can screw a spoke into a DT 16mm nipple without risk of damaging it. (This assumes that all spokes are threaded the same length of 9-10mm... i don't know if this is true or not, since I haven't even ordered mine yet.) The previous illustration shows that you can thread a spoke about 1mm farther into a 14mm DT nipple, and about 2mm farther into a 12mm DT nipple without risking damage.

So, to compensate for this, when using 16mm DT nipples, I should subtract 2mm from the example raw value of 253mm supplied by the calculator. That will leave me with 251mm, and if my distributor only stocks even length spokes I can either round up or down safely to consolidate the number of different lengths I will need for the build. I will be maintaining a 1mm safety zone between the position of the spoke in the nipple at optimum tension and the absolute limit if I order 252mm, while leaving me, still, with adequate threads engaged if i order 250mm.

blah~:madman: I will update this after i complete the build in the coming days or weeks: 823/Hope Pro II F, 823/Hadley 135X12 R.

· Registered
49 Posts

I completed the build and everything turned out fine. I used 254 on both sides of the Pro II front hub, but I feel I would have been better off with 252 on the shorter side. I was able to get 6.5 turns on all the nipples before some started getting very tight. (This was out of a possible 11 full turns between when the threads first dissapear into the nipple and when the spoke bottoms out.) I then dished the wheel 1 turn to the left, and measured and equalized tension to the desired amount. I stopped counting revolutions at this point, but I imagine some spokes became screwed in up to 10.5 turns on the side I dished towards. I used 252 on the right and 254 on the left with the Hadley 135 rear hub with similar results.:thumbsup:
The following is some advice I could offer to other first-timers working with EX823's. It may not be the best way to do it, but it seemed the most logical to me, considering were working with both lube and threadlocker on the same small part.
1. Line up your eyelets on the table in a line and swab the insides with your lube, then carefully wipe off any excess clinging to the inner lip or outside surface.
2. I hope you have liquid threadlocker, because it seems much easier to put a drop into each eyelet hole in the rim, than try to rub a stick of it onto the outside of each eyelet.
3. Hold an eyelet in your hand and drop a nipple into it, then screw it into the rim finger tight. Mavic warns that anything less than a 16mm nipple is able to become lost inside the rim, so don't do this if you're using 14mm without checking first. When all 32 or 36 are done, torque down to 5N*m or whatever.
4. Insert all the spokes into the hub following the pattern of a wheel you trust is built correctly. Mavic warns that the braking spokes (the ones lying on the outside of the hub flange on the disc side should be angled counter to the rotation of the wheel. If you don't put in all the spokes before you complete one side you'll have to bend the outside spokes on the remaining side to get them in.
5. Only put spoke prep or lube onto the spoke threads just prior to screwing it in.
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.