bjtesch

first question:
I bought some 32 hole Mavic CXP33 rims and DT 15/14 spokes to go on my old 130mm rear hub. I've been doing some searching for recommended spoke tension. I found some information where Mavic recommends 90-110kgf. I found other information recommending 110kgf front and up to maybe 180kgf for the drive side of the rear. When I tighten my rear wheel to about 110kgf on the drive side with rim centered the spokes on the left side seem fairly loose. If I was building these wheels without a tension gauge I would certainly tighten them a lot more. On a rear wheel should I go ahead and tighten the drive side a little bit more?

second question:
What is the downside to not building a rear wheel perfectly centered? If I center the rim then the non-drive side spokes will be a lot less tight than the drive side spokes. It seems that it would be acceptable to fudge a little bit on the centering in order to better balance the spoke tensions. Does this cause a problem? Does it cause the bike to track very slightly off if the rear rim is not centered between the dropouts?

Bill Kapaun

Typically, on a rear, your NDS tension will be 50-70% of DS, depending on the difference between the offsets of the hub flanges.
That's just the nature of the beast.
It seems most of us shoot for about 110kgf on the DS, but will increase it some to try to get at least 65kgf on the NDS.

180 kgf is TOO MUCH!

bjtesch

(Now that I have the fancy gauge, I need to build up enough courage to check the last set of wheels that I built, over 20 years ago.)

Matariki

If those wheels are still functional, you may be pleasantly surprised at how close you came by feel.

rpenmanparker 

Yes, the DS rear tension should be about 110 kgF or how much more it takes to get at least about 65 kgF on the NDS. Everything within reason, however. When I build wheels with nearly even tension on the NDS and DS because I am using twice as many spokes on the DS as the NDS (due to an extremely big flange offset difference), I like to have 120 on the DS and whatever comes out on the NDS. Normally I will find the NDS to be about 100.

bjtesch

I finished the new wheels today. I'm using a Park tension gauge to measure the tension and I was able to set the front wheels at 100-110 kg. The rear wheels I got to almost 90 kg NDS and about 130 kg DS. My dish is about 2-3mm off of center.

Now that I have the gauge, I checked my old wheels just for grins. I have one set of wheels that I built over 25 years ago and have ridden a lot since then- Wolber TX rims and 2.0mm spokes. The fronts are 76-107 kg. The rears are 62-85 kg NDS and 107-137 kg DS. The spokes are fairly uniform, with just a few off more than the rest one way or another. Even though the spoke tensions are all fairly good and I have not had any problems with these wheels, I think the rear needs a bit of touchup on its truing. I don't recall that I've done that before.

My other set of wheels came on a used bike that I bought 23 years ago. I have ridden these wheels a lot and not had any problems with them, I don't recall that I have ever done any truing on them. The spoke tensions on these are not as uniform as the ones that I built. The maximum tensions of the front wheel were 68 kg, with a lot of the tensions much less and a couple almost zero. The rear wheel tensions are at 137-179 kg DS and 56-107 kg NDS. I'm surprised that the DS tensions are so high, and that the front wheels have performed well with such erratic spoke tensions.

Dream Cyclery

FYI, Parktool Tension Meter is not very accurate when you measure higher tension. Not too bad on lower tension, but still not consistent enough for a great wheel build. When you use the TM-1, try to measure the same spoke multiple times to get reasonably accurate reading.

bjtesch

I understand what you mean because as a structural engineer I understand the concept behind the function of the tool, but it is the best that I have available to me. Even in my profession measuring bolt tension is a very crude practice. The wheels that I built 25 years ago were the second set of wheels I ever built, and built without any tool for measuring tension. I found it interesting that they were tensioned fairly evenly, were in a reasonable ballpark for actual tnesion numbers, and have been ridden quite a bit for 25 years.

Bill Kapaun

I'll venture the rim is too close to the NDS side with 90kgf NDS. Back it off some.
IF you had been using your tension meter, you would have seen it was getting too high for proper dish.

One trick I use for old wheels to VISUALIZE tension variance-
I got a bunch of small color coded alligator clips from Radio Shack.
I go around the wheel with the tension meter to get an idea of the average tension per side.
I then go around it again and put a RED clip on the high readings and a green clip on the low.
Basically 1 clip per tension division on the meter. IF it's more than 5 divisions, I add a yellow clip as a +5.
If a wheel is WAY OFF, I'll us a different "scale" where a clip may be worth 2 or 3 divisions.

Once installed, you can visualize things pretty well to see if you have adjacent high & low spokes that can be equalized without affecting dish etc. (or not)
Depending on how far off the tensions were, I repeat as necessary.
It's pretty slow on a bad wheel, but it works for me.

Retro Grouch 

180 kgf! I don't think I could ever get even close to that. I'd think the nipples would round out first.