Rear wheel tension

Insaneclimber said:

Hey im a specialist climber and ive been experimenting with the rear wheel tension so as to inprove rigidity.

Does anyone have any experience with this? Im wondering how much i can overtension befor ill get problems. Important things to note are i only weigh 65kg, and its a 32 spoke wheel with s/s spokes.

More tension is good, though it probably won't change the lateral stiffness too much. The question you need to ask is: as I increase tension, which part is going to fail first?

The spoke itself is far enough away from the yield point in most cases that it's safe to increase the tension. In fact, increased tension will increase its fatigue life. I.e., it'll take longer before the spoke breaks.

Spoke nipple? Shouldn't be a problem there, either.

Rim? I think there's a danger that with increased tension you can reach the yield point of the rim. With lower spoke count, higher spoke tension and lighter rims, there are plenty of examples on the internet where people have had spokes pull through the rim. Another danger is fatigue cracks that start at the eyelets.

Hub? The hub flange can also be a weak link. Too much tension can cause deformation and possibly premature fatigue failure.

The manufacturers of these parts, or even your wheels, will have a recommended range of spoke tensions to use. Your local shop can probably help you get those numbers. Personally, I would only use the recommended spoke tensions for safety reasons.

Insaneclimber said:

Hey im a specialist climber and ive been experimenting with the rear wheel tension so as to inprove rigidity.

Does anyone have any experience with this? Im wondering how much i can overtension befor ill get problems. Important things to note are i only weigh 65kg, and its a 32 spoke wheel with s/s spokes.

"Some believe that a wheel built with tighter spokes is stiffer. It is not. Wheel stiffness does not vary significantly with spoke tension unless a spoke becomes totally slack."
A quote from an article written by Damon Rinard.
The entire text:
http://www.sheldonbrown.com/rinard/wheel/index.htm

daveornee said:

"Some believe that a wheel built with tighter spokes is stiffer. It is not. Wheel stiffness does not vary significantly with spoke tension unless a spoke becomes totally slack."
A quote from an article written by Damon Rinard.
The entire text:
sheldonbrown.comindex.htmOpen ↗

I understand what your saying and i do agree but the reality is i can feel the extra tension, and this feeling of tension gives more confidence. i reciently changed to chromo cranks for the same reason and the change was quite dramatic although i know that on paper the extra regidity is minimal it does give a different feel. remember that lightweight riders like me ride hills in a high gear compared to most and this also seems to flex things a little more.

Insaneclimber said:

I understand what your saying and i do agree but the reality is i can feel the extra tension, and this feeling of tension gives more confidence. i reciently changed to chromo cranks for the same reason and the change was quite dramatic although i know that on paper the extra regidity is minimal it does give a different feel. remember that lightweight riders like me ride hills in a high gear compared to most and this also seems to flex things a little more.

No doubt about the difference in feel.
The reason I referred to the Damon Rinard article are his measurements and conclusions on what factors contribute to lateral wheel stiffness.
Climbing and sprinting are usually the disciplines that expose the instaneous peaks and lulls in the pedal stroke.

Insaneclimber said:

i reciently changed to chromo cranks.

Really? What sort? Not even the bulkiest track sprinters use steel crank arms.

What type of rims do you have? I assume if you want stiff wheels for climbing, you're riding up hills that aren't so steep (not much lateral force generated if you're creeping up a 15% mountain 🙂), and you're spending some time off the saddle.

The best thing for a stiff wheel is a deeper rim. I have some clunky old Mavic CXP30s, which are stiff as bricks, totally bomb proof, but kinda heavy. If you're going up long, steep climbs, you obviously don't want heavy wheels. There lies the conundrum: weight vs rigidity, and the best way to get the best of both worlds is buy very expensive carbon wheels. 🙂 Other than that, if you stick to affordable wheels (aluminium), you've gotta find that balance between weight, stiffness, durability and price! Some companies make light wheels which they claim are stiff, but their durability is probably questionable.
I recommend something around 25mm or deeper.

In my opinion, forks are often overlooked when it comes to out of the saddle, lateral rigidity. People buy light, comfortable forks, but they get off the saddle, and their weight moves forward, the forks flex all over the place. I had a light and flexy full-carbon Mizuno fork on one of my bikes, then I changed to a Columbus Link fork (alu steerer), and the difference was amazing -- it was like a differnent bike. Generally, forks with alu steerers tend to be stiffer than light, full-carbons

Insaneclimber said:

Hey im a specialist climber and ive been experimenting with the rear wheel tension so as to inprove rigidity.

Does anyone have any experience with this? Im wondering how much i can overtension befor ill get problems. Important things to note are i only weigh 65kg, and its a 32 spoke wheel with s/s spokes.

Lacing up the wheels with STRAIGHT gauge spokes will produce a laterally stiffer wheel ...

With a x3 on the drive side AND x2 on the non-drive side, wheel stiffness should increase ...

A 36h rear wheel will be stiffer than a comparably laced 32h rear wheel.

Insaneclimber said:

I understand what your saying and i do agree but the reality is i can feel the extra tension, and this feeling of tension gives more confidence. i reciently changed to chromo cranks for the same reason and the change was quite dramatic although i know that on paper the extra regidity is minimal it does give a different feel. remember that lightweight riders like me ride hills in a high gear compared to most and this also seems to flex things a little more.

Another look at your response leads me to another reply:
Reading the previously referenced Damon Rinard article;
"Relative contribution of the following to stiffness:
number of spokes
spoke gauge
rim weight (I'll assume he is talking only aluminum here... not mixing in carbon fiber)
hub flange spacing (I'll add hub flange diameter... both contributing to larger spoke support angles)
rim height"

What you feel may be positive and tightening to a point (see ScienceIsCool's earlier reply giving good analysis on the subject) may increase the durability of the wheel; however, it is not increasing the stiffness unless you started with spokes that were totally slack.

Thanks guys some good tips there i didn't think of

It occours to me that what im looking for is rotational rigidity so im not sure about the straight spoke idea? oh and i never said it was a road bike lol, im an xc nut. i think ill get deep rims and a 36 spoke wheel. I can afford carbon but is it realy more rigid?

Insaneclimber said:

Thanks guys some good tips there i didn't think of

It occours to me that what im looking for is rotational rigidity so im not sure about the straight spoke idea? oh and i never said it was a road bike lol, im an xc nut. i think ill get deep rims and a 36 spoke wheel. I can afford carbon but is it realy more rigid?

I'd say carbon would be stiffer if it's 50mm deep, or more! 🙂

In my opinion, 36 spokes isn't necessary, unless you're over 220 lbs. I'm about 200, and my 28 and 32 spoke 30mm deep Mavic CXP30s are stiff enough.

as I suggested above, the fork is often overlooked when it comes to frame stiffness.