Wheel building tension issue

[tuba_transport]

For all you experienced wheelbuilders out there I have a question.

I bought some Dura-Ace Open-Pro prebuilt wheels off of PerformanceBike.com. Why not a local shop? Well I got the wheels fully built with 2008 Dura-Ace hubs, Mavic Open-Pro rims, and spokes for just $85 more than it costs for the rear hub alone. It was a crazy cheap deal.

Anyways.

I went to retension and true them after the first 70 miles or so. The rear was a little out and the overall tension was low.

The rear seemed OK. I may have added 1/8 to 1/4 all the way around and then the tension was just about right at ideal on the drive side. Around 110kg according to my Park tension tool. Took out my Park dish tool and the dish looked pretty darn close. Good enough.

Now I went to the front wheel and there was a good difference between one side and the other. One had the Park tension tool at 21, which is the 110kgf ideal I was shooting for, and the other side hovered around 15 or so all around. I get out the dish tool and the higher tensioned side is still slightly more outbound than the lower tensioned side.

So to keep the dish relatively close, and it is still out my a couple of mm, one side needs a good bit lower tension that the other on the front.

Any ideas why?

[punga]

Calling on Dirt! Calling on Dirt! Pete, are you out there?!

[rciracing]

On a front wheel, the tension should be even on both sides unless its a front disc wheel. It almost sounds like the spokes are different lengths. Or maybe something is not seeding properly. Are you are comfortable removing a spoke from each side to check length? I would probably loosen things up on both sides and try to build again.

[BikerMiker]

this has nothing to do with spoke length unless you can't tighten one side (meaning the threads are bottomed out).

sounds like the front rim is compromised and spoke tension is making up for it...

plus, who cares? just adjust your brakes. you'll be fine...

mike

[tuba_transport]

sounds like the front rim is compromised and spoke tension is making up for it...

plus, who cares? just adjust your brakes. you'll be fine...

mike

I was thinking perhaps the axle was sticking out slightly more on one side and the tension difference was needed to keep things centered up.

You are thinking it might be a rim issue. The whole shebang is brand new. I hope it ain't a bum rim.

I am going to keep riding it and that will be that.

It should be fine for my Tour de Mid-Atlantic over the next few years.

[jabberwocky]

I can't imagine its the rim, as long as the tension is even on either side. I mean, of all the drive side spokes are the same and non-drive side spokes are the same, it means the rim is true.

It sounds like the hub is skewed to one side or something. Honestly, as long as the wheel is true and the tension relatively even on each side, I wouldn't worry about it.

[kenholmes]

having the higher tension side more "outbound" is correct and would be the natural outcome of unequal tension on left vs. right side spokes as long as the tension is equal around the wheel for each side. if I am understanding your description correctly this wheel is just out of tension. I dont know what the 15 mark ends up being on the park meter but that number should go up radically with just a small amount of turning as it is fighting the pull of the tighter side. what this ends up meaning in terms of dish is I would assume to be specific to the individual rim an spoke + cross combo, I would not even take a guess as to how much its going to move. but there is more here than meets the eye.

there is the question of whether or not the rim is defective and out of round to begin with but unless the eyelets are uniformly pointing to one side of the centerline of the rim (your brake pads would not squarely contact the rim) and the fact that you are saying that per side tension is uniform, this baby is just out of tension, most likely due to bringing the sides up unevenly when built (my less than savvy knowledge on wheels).

just think of what happens when you lock up the threads properly with tension on the high side and because the rim is already loaded there is never adequate enough slack to properly seat the threading on the low side. simple screw fastener principle, this is why when you build wheel you need to take the stress out of the spokes and nipples, it is getting the tension on the contacting surfaces of the threads to settle so that they just dont slip out under the first bits of torque put into the wheel (you can also then load on a higher tension). then you tension again. which is now where you are in the process. that may be a poor explanation of this but I have never been educated in this properly so you are on your own my explanation.

hope the input helps.

ken

[Dirt]

The reason the tension is off is that the wheels you purchased were most likely built without the aid of humans. Machine built wheels are usually off tension.

My best recommendation if you want a nice wheel would be to slowly de-tension the wheel, take it apart, put spoke prep on the threads of the spokes and rebuild it with new nipples. You'll end up with a wheel that is probably 90% as good as if you'd had a hand-built wheel the first time.

Yes. I am a wheel snob. Sorry about that. You can surely just ride it and enjoy the wheels as is. Tons of people ride machine built wheels with no problems for years and years.

Talk to you soon.

PEte

[rciracing]

this has nothing to do with spoke length unless you can't tighten one side (meaning the threads are bottomed out).

sounds like the front rim is compromised and spoke tension is making up for it...

plus, who cares? just adjust your brakes. you'll be fine...

mike

If the spokes on one side are collectively shorter than the other side, won't the one side pull harder and equal higher tension...assuming you are bottoming out on the theads?

Either way, I would just back everything out a bit and then re-tension and true while checking the dish frequently.

[rockhead]

Here's a more conservative suggestion. I agree with Ken's assessment that the tension-dish relationship you describe makes sense for a wheel that was tensioned improperly - tigher on one side than the other, but still both round and true. Given that, I wouldn't start by going through the trouble of detensioning and rebuilding. Simply back out all the tighter spokes by maybe a hlf turn at a time and then tighten the looser side by about the same, check your dish and repeat until you have the dish right. Make sure you work all the spokes on a side the same. Once the dish is correct, the tension should be about equal on both sides, but will likely be lower than desired. Now you can gradually tighten all spokes equally until you get the tension correct on all spokes.

Granted, this isn't quite as good as redoing the whole thing with fresh nipples and spoke prep, as Pete recommends, but it should hold up pretty well and save you a lot of work.

[BikerMiker]

The axle doesn't move the wheel side to side, the lock nuts do. You may have one more or less spacer in the locknuts on the hub so you could mess with that. No reason to not try it. If it allows you to get the tension even L to R, it's a good call for sure. That's thinking!

Shorter spokes on one side with ALL spokes bottomed out vs shorter spokes on ONE side with ONE side bottomed out means uneven tension vs maybe not. It won't cause this problem every time.

I'll be building some mtn race wheels tonite... (this is for Pete) Alpine III spokes, DT disc xc rims, King ISO hubs, 28h. Should be sweet, eh?

mike

[Dirt]

I'll be building some mtn race wheels tonite... (this is for Pete) Alpine III spokes, DT disc xc rims, King ISO hubs, 28h. Should be sweet, eh?


Sounds like an awesome set of wheels. Fast and light. You'll have fun with them.

[Dirt]

Now I went to the front wheel and there was a good difference between one side and the other. One had the Park tension tool at 21, which is the 110kgf ideal I was shooting for, and the other side hovered around 15 or so all around. I get out the dish tool and the higher tensioned side is still slightly more outbound than the lower tensioned side.

This is performance we're talking about, right? You can just take it back to them, tell them that you're very dissatisfied with the wheel and you'd like them to fix it for you.

[rsosborn]

For all you experienced wheelbuilders out there I have a question.

So to keep the dish relatively close, and it is still out my a couple of mm, one side needs a good bit lower tension that the other on the front.

Any ideas why?

just for reference i went back and checked the weather report for the day you posted this. just as i suspected, there were a good deal of sunspots that day.

if you check your wheel now, i'm sure you'll find everything is alright.

[allencb]

This is performance we're talking about, right? You can just take it back to them, tell them that you're very dissatisfied with the wheel and you'd like them to fix it for you.


Pete beat me too it, but yeah, don't be afraid to say you don't like how something is working or holding up. I've taken stuff back to them weeks after purchase and use because it didn't live up to my expectations.

Chris

[EJensen]

I get out the dish tool and the higher tensioned side is still slightly more outbound than the lower tensioned side.


Assuming there is some way to explain how a wheel could have one entire side at a higher tension than the other on a hub with an equal L/R center-to-flange dimension, isn't what you described what you would expect? I assume that by "the higher tensioned side is still slightly more outbound than the lower tensioned side" you mean that the rim is closer to the flange with the higher tensioned spokes than it is to the other flange. If this is the case, then increasing tension on the spokes on the lower-tensioned side would have the effect of pulling the rim toward center.

Sorry if I am misunderstanding your description.

Regards,
Eric

[tuba_transport]

Assuming there is some way to explain how a wheel could have one entire side at a higher tension than the other on a hub with an equal L/R center-to-flange dimension, isn't what you described what you would expect? I assume that by "the higher tensioned side is still slightly more outbound than the lower tensioned side" you mean that the rim is closer to the flange with the higher tensioned spokes than it is to the other flange. If this is the case, then increasing tension on the spokes on the lower-tensioned side would have the effect of pulling the rim toward center.

Sorry if I am misunderstanding your description.

Regards,
Eric

I may have been unclear.

By outbound, I meant the end of the axle is further out on the higher tensioned side, not the rim.

I will get out there sometime with a caliper and check out the distance from the hub shell flange to the end of the axle on each side. I will guess that there is a discrepancy there.

If I were to even out the tension left to right now, then the axle would be out even more than it is now on the dish tool.

[EJensen]

I may have been unclear.



Since I am the only one who got it wrong, it's more likely faulty reading than writing.

By outbound, I meant the end of the axle is further out on the higher tensioned side, not the rim.

I will get out there sometime with a caliper and check out the distance from the hub shell flange to the end of the axle on each side. I will guess that there is a discrepancy there.

Your response raises another question, however. Are we talking about the lateral position of the rim with respect to the end of the axle or with respect to the locknut that bears on the inside of the fork dropouts? I don't have a dishing tool, but I believe that the measurement is taken with the center gauge in contact with the locknut, not the axle. The rim can be off center with respect to the axle, but that has no effect on centering the wheel on the fork. Since this is a cup and cone hub, it's easy to assemble with the hub not perfectly centered on the axle.

Again, if I'm just getting the facts wrong, sorry for taking the thread off-course.

Regards,
Eric

[tuba_transport]

Are we talking about the lateral position of the rim with respect to the end of the axle or with respect to the locknut that bears on the inside of the fork dropouts?
I was using the axle end as a reference. My assumption is that the 9mm axle ends are equal distances from the locknut.

I am going to ride it to work today and see if I break a dozen spokes thanks to my tinkering. This evening I might play with the wheel some more if I get time.

[jabberwocky]

My assumption is that the 9mm axle ends are equal distances from the locknut.This is not a safe assumption. :)