CXP33 - Spoke count?

padawan said:

I'm making the final decisions on a wheel build (rear only). I want to have one good strong wheel that I can use for both training and racing. I've landed on the Mavic CXP33.

Everything I've read about this rim talks about it's strength. I've seen it recommended for heavier riders (i.e. 200 + lbs).

I had originally planned to go with a 32 hole 3x build for strength. But I'm only 170 lbs (should be 165 by peak season).

My question, at my weight could I save some wheel weight by going to a 28 hole or 2x lacing or both and still keep the strength? I don't want to have to be truing the wheel all the time.

Love to hear from some 165-175 pounders that have used this wheel in a 28 hole or 2x config.

Cheers!

I build wheels for recreational and racing riders.
For a rear wheel, I think that with CXP-33 you would be best served with 32 spokes. If you want to shave some grams and still maintain durability you can use DT Revolution 14/17 DB or Sapim Laser 14/17 DB spokes on the left side. You will save equivalent weight to the 4 spokes of 32 Vs 28 spokes.
dave at ornee dot net

padawan said:

I'm making the final decisions on a wheel build (rear only). I want to have one good strong wheel that I can use for both training and racing. I've landed on the Mavic CXP33.

Everything I've read about this rim talks about it's strength. I've seen it recommended for heavier riders (i.e. 200 + lbs).

I had originally planned to go with a 32 hole 3x build for strength. But I'm only 170 lbs (should be 165 by peak season).

My question, at my weight could I save some wheel weight by going to a 28 hole or 2x lacing or both and still keep the strength? I don't want to have to be truing the wheel all the time.

Love to hear from some 165-175 pounders that have used this wheel in a 28 hole or 2x config.

Cheers!

Just so you know ... Using 2x lacing vs 3x is not really going to save you any significant weight. It's the same number of spokes, either way. With 2x lacing the spokes might be 1 or 2mm shorter. You're talking about less than 5 gm over the entire wheel. 3x will give you a stronger wheel, no question about it.

I agree: stick to 3-cross, but consider 28 spokes if you want, although any difference wouldn't really be noticeable. I have CXP30s in 32 and 28, and I can't tell the difference. As Daveo suggested, if you wanna save weight, perhaps get double butted spokes.

padawan said:

I'm making the final decisions on a wheel build (rear only). I want to have one good strong wheel that I can use for both training and racing. I've landed on the Mavic CXP33.

Everything I've read about this rim talks about it's strength. I've seen it recommended for heavier riders (i.e. 200 + lbs).

I had originally planned to go with a 32 hole 3x build for strength. But I'm only 170 lbs (should be 165 by peak season).

My question, at my weight could I save some wheel weight by going to a 28 hole or 2x lacing or both and still keep the strength? I don't want to have to be truing the wheel all the time.

Love to hear from some 165-175 pounders that have used this wheel in a 28 hole or 2x config.

Cheers!

I'm 167lbs, using silver CXP33 with 32h, 2x front and rear. IMHO, there is little difference in any of the configs mentioned above as long as the build is good. The wheels are coming towards 10000 miles without incident and I've had to true the rear once, though I think the front rim is wearing from brake wear.

Speaking of which, are there wear indicators on CXP33's?

Ritch

no wear indicators on CXP33s, unless they've changed them

http://www.mavic.com/ewb_pages/r/route.php

32 hole - 3x it is. I was planning to go with double butted spokes so I'll stick with that. As always, some good advice.

Thanks to all who responded!

padawan said:

32 hole - 3x it is. I was planning to go with double butted spokes so I'll stick with that. As always, some good advice.

Thanks to all who responded!

Also consider using alloy nipples. The weight saving is considerable vs. regular brass or stainless steel ones. I have a pair of CXP30 32h training wheels which have remained true for over a year. My wheelbuilder installed them unlubed.

If durability is the operative word the 32H 3X brass nipples will give you the best build. 28H would be great for the front wheel. At 170lbs you are still not a feather weight. The beauty of your selection is that once you have the hub and rim the cost of spokes and nipples are relatively minor. You can afford to experiment. With alloy nipples you have some limitation on the ability to get enough spoke tension on the drive side without starting to strip the alloy nipples. Just use the best and tightest fiting spoke wrench you can find Good luck.

hd reynolds said:

Also consider using alloy nipples. The weight saving is considerable vs. regular brass or stainless steel ones. I have a pair of CXP30 32h training wheels which have remained true for over a year. My wheelbuilder installed them unlubed.

Unlubed? Probably 'cos he/she has been sucked in by the old wives' tale that lubed spoke threads cause the spokes to unscrew themselves. It is a load of auld bollocks. An unlubed thread on a spoke/nipple is more likely to stick during the build, promoting spoke windup instead of actually tightening the nipple (i.e., a Bad Thing).

Lube away!

Ritch

Deanster04 said:

With alloy nipples you have some limitation on the ability to get enough spoke tension on the drive side without starting to strip the alloy nipples.

Huh? When you are building wheels the spoke tension is determined by the spoke diameter and the max tension on the rims, as specified by the rim manufacturer. So, if you are building a wheelset - front and rear - then the drive side tension on the rear will be the same as the tension on all of the front wheel spokes. Your statement that you'll start stripping the nipples is just wrong. If you believe that, then you'll be stripping ALL of the nipples on the front wheel.

Sorry, Deanster, but there are plenty of wheels that have been built with Al nipples that are not stripped. If that were not the case there would be no market for them. If you stay with the max specs and use a tensiometer, then you should have no problem.

Also, for hdreynolds, as ritcho pointed out, no competent wheelbuilder would even consider a build without lubing the nipples - especially Al alloy nipples.

Not the threads of the nipples, but the barrels, the part the spoke wrench contacts. I know that there are plenty Al nipples rolling around the world no disputing this fact. What you say is truer for the older narrower rear wheel widths, but with the 10spd wheels the dish is more extreme and the drive side tension is much greater than the front wheels. I am a heavy rider (220#) and after many years of building wheels I have found that a higher tension wheel is best for me. I ride Mavic open pro, DTSwiss 14/15 spokes, and record or chorus hubs using 32H and 3X. I currently have a set of 10spd wheels with 5K miles that I haven't touched with a spoke wrench since I built the wheels (by the way I went back to the old standby linseed oil for the lube and lock of the spoke in place instead of the modern high prices spreads). I recently built up a set of wheels trying Al nipples, DTSwiss revolution (thinDB) non-drive and comp (14/15 drive side) and experienced the stripping issue. Tried a brand new spoke wrench 4 sided and still had a problem. Went to the best wheel builder here in Boulder, CO and discussed the problem with the "master" and he agreed that with my size and need for higher tensioned wheels Al nipples weren't the best choice. This was my empirical experience. I've been building my own wheels since the 1960's. Although I have tuned some of the newer assymetrical (sexy) wheels for friends I realize that I just prefer the old standby especially when my fun meter hits the 50mph mark decending the steep roads here in the front range of the Rockies. Most contemporary parts are built for lightness and I am a relative lummox compared to my skinney riding buddies. There is never one truth just a myriad of empirical evidence that we go thru life seeing. Good luck and good riding.

fish156 said:

Huh? When you are building wheels the spoke tension is determined by the spoke diameter and the max tension on the rims, as specified by the rim manufacturer. So, if you are building a wheelset - front and rear - then the drive side tension on the rear will be the same as the tension on all of the front wheel spokes. Your statement that you'll start stripping the nipples is just wrong. If you believe that, then you'll be stripping ALL of the nipples on the front wheel.

Sorry, Deanster, but there are plenty of wheels that have been built with Al nipples that are not stripped. If that were not the case there would be no market for them. If you stay with the max specs and use a tensiometer, then you should have no problem.

Also, for hdreynolds, as ritcho pointed out, no competent wheelbuilder would even consider a build without lubing the nipples - especially Al alloy nipples.

This is why I come to you guys (and why I'm having some else actualy build the wheel for me).

My understanding of lubing nipples has nothing to do with wheel building! :p

Again, I appreciate the advice!

padawan said:

This is why I come to you guys (and why I'm having some else actualy build the wheel for me).

My understanding of lubing nipples has nothing to do with wheel building! :p

Again, I appreciate the advice!

Agreed! To lube or not to lube that is the question! Like Baptists (of the fundamentalist-evangelical pursuasion) some wheel builders think that there is only ONE WAY, but if you are using Ni flashed brass on SS eyelets you can easily get away without using a lube and it requires special tensioning methods of tightening and backing off the mark. Rarely would a person who does this for a profession use this method because of speed...it is however possible. Don't worry about the ABSOLUTE response little grasshopper.

I misread your response thinking it was the original thread starter. The following is for the originator.

Actually you should try and locate a wheel building course in your area and make an attempt. Better yet, buy the parts from a LBS that has an experienced wheel builder and offer to pay the person a fee if they coach you in building your first wheel. Buy Gerd Schranner 's book, Go to Sheldon Brown's website, and get Zinn's book Zinn and the Art of Road Bike Maintenance and read each of these sources carefully. Give an attempt to build your own wheelset and I assure you that it will be most satisfying to be riding your own wheels. A good wheel builder coaching you will work through the art of tensioning the wheel which is where most beginners freak out. If you do this you will feel great satisfaction and gain stature among your riding buddies...and the mystery of the wheel will be solved for you. Go For It!!!!!!

Deanster04 said:

Actually you should try and locate a wheel building course in your area and make an attempt. Better yet, buy the parts from a LBS that has an experienced wheel builder and offer to pay the person a fee if they coach you in building your first wheel. Buy Gerd Schranner 's book, Go to Sheldon Brown's website, and get Zinn's book Zinn and the Art of Road Bike Maintenance and read each of these sources carefully. Give an attempt to build your own wheelset and I assure you that it will be most satisfying to be riding your own wheels. A good wheel builder coaching you will work through the art of tensioning the wheel which is where most beginners freak out. If you do this you will feel great satisfaction and gain stature among your riding buddies...and the mystery of the wheel will be solved for you. Go For It!!!!!!

I'd like to do that. I am very much a do-it-yourself person. But since I'm putting a PowerTap hub into this wheel. I'm going with a particular wheel builder. I'll screw around a little more another time, perhaps I'll build a front wheel to match.

Deanster04 said:

..., but with the 10spd wheels the dish is more extreme and the drive side tension is much greater than the front wheels. ...

While we agree on most everything, this statement is the one I don't get. Assuming you are using the same spokes on both wheels and the same rims, there is only one maximum tension that you can use and it is the same for both wheels. The only different tensioning should be in the non-driveside spokes in the rear. They are usually going to end up at only 50-70% of the maximum that you should be using for the front wheel (both sides) and the rear drive side. Mavic states - both in writing and on the phone, that the maximum tension for their rims is in the 90-110kgF range. So, the limiting factor is the rims, not the spokes. I have OPs with double butted spokes myself. Those spokes will take a lot more than 110, so you go by the rim spec. If you use conventional wisdom to build your wheels you use the maximum tension you can. So, for OPs, that would be 110 on both sides for the front wheel and 110 for the drive side on the rear wheel. When I build a rear, I tension up the drive side to maximum and then do almost all the dishing using the non-drive side spokes. The non-drive side spokes are pretty much there just for dishing and truing. They don't do much for the strength and performance of the wheel. Those you get by using the max tension on the drive side, and that is going to be exactly the same max tension that you use on the front wheel. Do you see what I am saying?

If someone is telling you that the max tension for the front and rear wheels is different (assuming the same spokes and rims), they are wrong.

Hey fish,

I followed all of that upto this point...

fish156 said:

When I build a rear, I tension up the drive side to maximum and then do almost all the dishing using the non-drive side spokes. The non-drive side spokes are pretty much there just for dishing and truing.

I've even trued my own wheels a couple of times (with moderate success) but... for the padawan... could you explain dishing to me? 😕

One of these days I'd like to be building my own wheels!

Cheers!

padawan said:

Hey fish,

I followed all of that upto this point...

I've even trued my own wheels a couple of times (with moderate success) but... for the padawan... could you explain dishing to me? 😕

One of these days I'd like to be building my own wheels!

Cheers!

Sure, no problem. When you build a wheel there are several things you need to work on to build a technically good wheel:

1. Lateral true - this is so there are no side-to-side lumps in the wheel. When you apply your brakes slowly, they should not be hitting any "high" spots. Lateral truing makes the rim sidewalls in to a nice, even flat surface.

2. Radial true - this to make the wheel as round as you can. There should be no noticeable dips or protrusions (= "out of round"😉. It's all about roundness.

3. Tensioning - the strongest wheels have spokes that are as tight as you can get them. The tightness (or maximum tension) is usually determined by
by the weakest component in the wheel, and that is usually the rim. When you tension spokes you want to get them as tight as you can for both sides on a front wheel and on the rear drive side. In addition to max tension, you also need to check for "relative" tension. This means that you measure all of the spoke tensions and check that they are within 5%, or better, of each other.

4. Dishing - If you stand in front of your bike and look at the front wheel you will see that the two hub ends are equidistant from the middle of the hub.
And, the spokes slope away from the rim (to the hub) at equal angles. If you go around behind the bike and look at the spokes on the two sides you will see right away that the spokes on the drive side connect the hub to the rim at less of an angle than the spokes on the non-drive side (this assumes we are talking about a bike with a multi-sprocket cassette on the drive side).
This is done to keep the center of the rim centered between the frame dropouts - and, as a result, the brake pads. When you build a wheel, this centering does not just happen. But, it must be accomplished by the builder. It is accomplished by moving the rim - with respect to the hub - by tightening, or loosening, all of the spokes on one side or the other. This either "pushes" or "pulls" the rim towards one end of the hub or the other. It's pretty simple for a front wheel, as you just want to center the rim over the center of the front hub. Rear wheels are asymmetric, as you have a gear cassette on one side, but not the other. You must compensate for this by moving the rim (from side to side) over a point that is the middle point between the two ends of the hub. The process of moving the rim from side to side by adjusting the spokes is called "dishing".

A well built wheel should be lateral trued, radial trued, and dished to less than 0.5mm. This is the standard. Tensioning should be as close to the max as you can get and the spokes should be within 5% of each other (for any given side of the wheel).

Ok, that's the short version of what you should be shooting for. The industry standard for these kinds of things is Barnett's Manual. It will explain all of this in much more detail, and, if you are looking to build your own wheels, I highly suggest you read it carefully. Usually, you will pay $125 for a copy of Barnett's, but there are some chapters posted on their site for free download. Fortunately, the chapter on wheelbuilding is one of them. I suggest you download it and save it while it's free ;-)

bbinstitute.commanual.htmOpen ↗

Go to this page and scroll down to the bottom. Click on this link:

[font=Arial]Download Chapter 17: Wheel Truing and Repair [/font]

And, off you go to build your own wheels. This is a must for anyone building wheels and is the best reference I have ever seen, IMHO. It's very nice as it shows you at each step of the way how to check and see if you have made mistakes. If you are patient and take your time you can build some very nice wheels using Barnett's.

People will argue about what you need for tools, but the basic tools for wheelbuilding are:

1. Truing stand
2. Spoke wrench
3. Dishing gauge
4. Tensiometer

You can get away with just a spoke wrench, but it's a lot more difficult to do a good job, IMHO.

Ok, that should get you in enough trouble for now ;-) Have fun, young padawan.

-- obi-fish

[QUOTE=fish156 Ok, that should get you in enough trouble for now ;-) Have fun, young padawan. -- obi-fish[/QUOTE]
Many thanks Obi-fish for a thorough explanation!! I will defintiely download that section of Barnette's manual.

As I said, I'm having someone else build the wheel but now I'll be able to better assess how good a job they've done (and perhaps fix it if necessary)!

Cheers!

fish156 said:

3. Tensioning - the strongest wheels have spokes that are as tight as you can get them. The tightness (or maximum tension) is usually determined by
by the weakest component in the wheel, and that is usually the rim. When you tension spokes you want to get them as tight as you can for both sides on a front wheel and on the rear drive side. In addition to max tension, you also need to check for "relative" tension. This means that you measure all of the spoke tensions and check that they are within 5%, or better, of each other.

I don't know where you got this idea from, but the spokes only need to be tight enough to not go slack under riding loads. Any tighter than this and you will drastically decrease the fatigue life of the wheel. I've seen rims on over-tensioned wheels start cracking within a few thousand miles of riding. That's not what I would call strong. As for "relative" tension, if you get your wheel trued, rounded, and centered and there's a variation is spoke tension it means that the rim was bad to begin with.