Asi

I hit a pothole and severely damaged my rear wheel with Mavic MA40. No broken spokes, just a bend in the sidewall and a nasty crack all around a spoke hole (it's about to snap the eyelet out of the rim along with a 1cm*1cm part of the rim, the rim is cracked around the eyelet with a 2mm gap)

Ok, it's history, I want to change the rim.

If I would want to keep the same spokes (which are stainless dtswiss and in good condition), then I would need a rim with the same ERD which is tough to find (Mavic MA40 has 614mm ERD). The obvious replacement would be Mavic open sport or open pro, but both have to small erd for 3x configuration (608mm erd) and too great for 4x building.

I somehow managed to find a nice fit: Mavic CXP22 since this have 599mm erd, and it would require the EXACT same length of spoke that I have right now, but with a 4x configuration. (296mm spoke length)

Now the questions:

What is your opinion about MAVIC CXP22? Does it worth the price? (it's pretty cheap)

Does the 4x crossing would interfere on a 45mm pitch spoke circle on the hub and 36spokes?

Does the increased tension in 4x building make the wheel more fragile? (yet it's 36h)

I do the building by eye and ear, yet, how much tension should I use on 4x crossing with 296mm spokes, and CXP22 rim (700C) 36holes?

AEO

although I would just recommend using new spokes, since you ask...

4x on a cxp22 with 36h would be too much and the spokes holes will be overlapped by neighbouring spokes, creating new problems.
the spoke tension does not change with a change in cross number.

for CXP22 you can go up to around 120kgf, but 100kgf should be just fine as well.

noglider 

It is not necessary to change your spokes, unless they are damaged.

As AEO said, the new spoke pattern will not affect tension.

4x should work fine.

I don't know about that rim, but I like Mavic very much.

mrrabbit 

https://www.mrrabbit.net/wheelsbyflemingapplications.php

Download the spreadsheet...play and experiment to your hearts desire...

mrrabbit 

MA-40 700c ERD=612
MA-40 27" ERD=618

=8-)

Asi

Thanks, I didn't know the tension was the same for any* pattern (3x or 4x).
As far as spokcalc and dt calculator and other calculators recommend 296.4mm spokes (for 4x with cxp22), and right now I do have 296mm spokes, and if I calculate the spokes needed for my actual tacoed wheel (MA40 3x) i find the exact 296.4mm spokes, so cxp22 laced in 4x should work. I'll try a quick drawing in autocad to see if the heads of the spokes would interfere on a 45mm flange (spokecalc should have signaled when interfering of the heads occur, but it said it's ok with 4x)

I have done previously a 4x lace wheel with some high flange hubs and did not interfere. (80mm flange)

as for 614 or 612 or 618 erd of MA40 really does not matter, it's MA40 made in 1987. Dt swiss calculator said 700c MA40 are 614mm, but that's just trivia, since MA40 is no longer to be found, I have to find some replacement and so far cxp22 sounds like a nice choice.

noglider 

4x is fine on a small flange hub with 36 holes. I've done it many times.

mrrabbit 

My spreadsheet includes a tab with a guideline for #hole versus #crossings...and of course it shows "green" for 4x on 36...

It's my favorite part of my spreadsheet actually...with colors and all.

Maybe DHS will get jealous!

=8-)

bjtesch

If you are still studying it- you could search for the spreadsheet spocalc.xls, it has the ERD data for a lot of rims. You might find another possibility that would work for you. Another thing- if you find a rim with slightly larger ERD then you could buy some 16mm nipples instead of 12mm nipples, effectively lengthening your spokes by 4mm. The spokes are about 15 cents each so this wouldn't be a big expense.

operator

CXP22 rims are garbage.

4x? Seriously? Do you weigh 300lbs+? Putting this on a tandem?

noglider 

There's nothing wrong with 4x. It's no better than 3x, and no worse, either.

operator

It's more akward to build than 3x for no absolutely benefit, so why bother?

furballi

I've build wheels with CXP22...stronger than Open Sport or Open Pro. The quality control is just so so with these non-welded rims. Exchange the rim if there is a gap at the pinned joint. I didn't have any problem holding +/-0.001" axially and radially with the CXP22.

noglider 

I don't find 4x awkward at all. The benefit for Asi is that he gets to reuse his spokes on a rim with a different ERD.

mrrabbit 

I'm siding with Operator a little on this...

Sure reuse the spokes...I'm all for it...but going 4X is simply carrying more weight for no benefit. Simple visit to the LBS with a spoke machine and voila! 3X!

=8-)

mrrabbit 

Nipples are not spokes...

=8-)

noglider 

Replace 36 spokes for how much money, to save how much weight? Let's see the numbers. He's been riding these spokes, and they haven't been deemed too heavy yet. Now that he's getting a rim with a slightly larger ERD, the spokes are too heavy? I don't think so.

operator

Spoke replacing - spokes do have a fatigue life. If the OP has put loads of miles on the wheel then really, it's a waste of labour NOT to lace with new spokes on a rim replace. Forcing a replacement rim (a mediocre one) to be the same ERD to reuse $15 of spokes really makes no sense.

mrrabbit 

I think you have it backwards...

Old = Mavic MA-40 = 612
New = Mavic CXP-22 = 597

=8-)

Asi

yes, MA40 have insanely large ERD and are laced 3x, for another replacement I should have same ERD for 3x, a slightly smaller erd (like 599) for 4x, and a slightly bigger for 2x. 2x and 3x are out of the question, so 4x should do it.
I have some wheels with remerx taurus rims and some shimano hubs that I have laced 4x and lasts well.

Since it's the everyday bike, I'm not a weight weenie, and other aspects, a heavy rim, with 36 spokes it's ok for me. I'll reuse the spokes since none of the spokes have ever broken on the old rim, and also they are DT Swiss stainless straight 2mm with a nice chrome finish.
Spokes are not .15cents (here), (in fact they are cheaper, but a very low quality, for DT Swiss I should place an order and wait a few weeks and also DT's are more expensive due to international shiping) I don't have a trusty LBS around, and also I do my own wheels, truing, lubing, replacing, etc and works quite well.

Conclusion:
I'll reuse the spokes
I'll do 4x (I had done it before with no problems)
I'll go with cxp22 (or cxp23- I saw they have the same ERD 599)

noglider 

operator, 36 spokes cost $15? I don't think so.

Some people reuse their spokes through many, many rims. I recently replaced a rim on 55 year old wheels. No problem. The better the wheel is built, the longer the fatigue life. In practice, that life can exceed the life of a human.

Also, notice that Asi is in Rumania. I imagine $50 takes a long time to earn there.

mrrabbit, you're right, the new rim has a smaller ERD, not larger.

Asi

I can see that the spokes are in good condition, and also they are some decent quality (DT), so I'll reuse them.

Here the problem is with price (DT's cost more here than in US because I didn't find in any LBS in store, only in other country, and that is seriously more expensive due to shipping from germany, UK, italy france or other country) and that will overshoot the price up to 25-30$ in shipping. Not worth it. Otherwise there are some chinese junk at less then 10cens/spoke+nipple, but that is JUNK not DT.

And of course, the money in $ is a bit pricey for this country. But that's not the problem, but I'd hate to pay twice the price only for shipping. And by mistake I found a Mavic cxp22 in Bulgaria (in Ruse), and I'll go get it this weekend (by bike it's only 80km from my home)

bjtesch

I'm going to rebuild a set of my old wheels and I'm keeping the rims and replacing the spokes.

Ok rabbit, I made a typo. I just ordered spokes and nipples to build 2 sets of wheels. DT DB spokes were $0.79 each, nipples were $0.15 each.

operator

Uh, yes? 50 cent for DT champion 2.0 at FULL retail from a REAL shop.

nymtber

yea, that's $18

I agree though. Buy new spokes for the $18-25 it would cost. Its worth it in the end.

Brass nipples might be OK to reuse if they haven't been rounded.

I paid something like $0.75 per spoke for wheelsmith 14/15ga double butted spokes from a bike shop. Not bad...