The wheelbuilding thread

Everything about building wheels, glueing tubs, etc.
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WinterRider
Posts: 337
Joined: Tue Feb 05, 2013 2:46 pm

by WinterRider

bm0p700f wrote: In a hard impact the spoke can go slack and in those circumstances the radial stiffness will drop a bit. Increasing the spoke tension will mean more load is required to make the spokes go slack, it can't increase the stiffness of a wheel though. That is entirely determined in a tensioned wheel by the lenght of the spokes and the stiffness of the components. Those material properties are not effect by tension.

All pre stressed system are "stronger" than unstressed one think of heat treated shatter proof glass. The heat treatment put the surface in compression therefore a higher bending load is required to break the glass. The material properties of the glass are the same (or nearly the same) but the pre tension is the bit that gives it its toughness.


I was to date thinking of the rim as a tensioned system vs the actual relative stiffness of the rim as a component. Your rating the rim as an individual unit.. I get that now.

I made an erroneous assumption earlier.. equating spoke deflection as measured by the Park tool to a kgf level. In truth.. thinner spokes just achieve those kgf levels with less measured deflection. So if your only 50% NDS your kgf level does not increase just by adding lighter gauge spokes. I'm back to my original view of NDS light butted spokes: saves weight, lessens elbow strain via the mid section absorbing re-tensioning shock.. yet reduces lateral stiffness.

So I'll continue to refine my ideas for the triplet... for heavier loads: geared to lightest practical rear.

NDS's under low tension make no sense to me.

bm0p700f
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by bm0p700f

NDS spokes under low tension work though. On my winter bike on awfull suffolk roads has NDS spoke (lasers) tension in the region of 480N (maybe a tad less), no spoke freeze and alloy nipples. So far after 6 months of riding I have not had to touch these wheels. I do 70-100 miles a week on them.

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WinterRider
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by WinterRider

bm0p700f wrote:NDS spokes under low tension work though. On my winter bike on awfull suffolk roads has NDS spoke (lasers) tension in the region of 480N (maybe a tad less), no spoke freeze and alloy nipples. So far after 6 months of riding I have not had to touch these wheels. I do 70-100 miles a week on them.


Yes they will work fine at lower wts.. and good builds. My winter bike is 26" MTB so NDS tension is a better ratio.. no problems. I break spokes but that bike is the 'recycle bin'... misc used spokes & parts etc... sacrificed to the salt season. The bike while a green color appears white some days. My mileage is about same too.

Just.. breaking a NDS spoke many miles from home with a DOA cell battery.... got me to TRIPLET's... :thumbup:

thisisatest
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by thisisatest

Thinner spokes achieve the same tension with more deflection (edit: more deflection of the SPOKE). On the park tool, a lower number is more deflection, up to the point where the tool is completely relaxed and forcing the spoke to a greater bend. That, and the thinner spoke takes up less room in the tensiometer itself.

brearley
Posts: 354
Joined: Mon Aug 11, 2008 10:08 pm
Location: Hull

by brearley

Hello guys,

I am looking for a new rim to build into a front wheel.
I already have spokes, nipples and hub from a wheel which is now bent so I need a new rim.
The ERD of that was 604mm. What variance have I got from this number?
can anybody give me suggestions on a rim to use, preferably 23mm wide, stiff, strong, light and relatively cheap.

I'm in the uk let me know what my options are

styrrell
Posts: 167
Joined: Mon Apr 19, 2010 10:33 pm

by styrrell

Looking to build a budget light clincher wheelset. Great thread but I've waded through it and have a hard time keeping some stuff straight, so two questions

I've seen here that Dati rear hubs have a short center to DS measurement, but a drawing on a ebay listing shows it at 19. 19 seems pretty wide, can anyone confirm if this is correct or is Dati fudging things to make the hub look better?

2nd, on a 24 hole rear, can the DS spokes be laced heads in/cross 2 for more stiffness, or can this cause problems?

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kavitator
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by kavitator

bm0p700f wrote:Kgf per unit are is pressue essentially which is stress when applied to solid.

In a hard impact the spoke can go slack and in those circumstances the radial stiffness will drop a bit. Increasing the spoke tension will mean more load is required to make the spokes go slack, it can't increase the stiffness of a wheel though. That is entirely determined in a tensioned wheel by the lenght of the spokes and the stiffness of the components. Those material properties are not effect by tension.

All pre stressed system are "stronger" than unstressed one think of heat treated shatter proof glass. The heat treatment put the surface in compression therefore a higher bending load is required to break the glass. The material properties of the glass are the same (or nearly the same) but the pre tension is the bit that gives it its toughness.


I had wheelset on rims kinlin xr200, Bitex hub, 28 spokes rear (DS 3x race, NDS radial laser).
tension was on DS around 120kg (parktool TS) - test rider (almost elite racer) noticed wheel is not very stiff (rubb in barekpads) - i put more tension on spokes (around 140kg on DS- parktool TS).
Wheel was noticebly stiffer-
So high spoke tension is need if powerfull rider wants the best from wheel.
But 140kg is too much for aluminium - it was test wheelset (and after 8.000km is still ok)

KLabs
Posts: 380
Joined: Wed Dec 01, 2010 4:29 am

by KLabs

Hi kavitator, yes spoke tension (as does bracing angle and rim width) affects lateral stiffness (ie in preventing brake rub), and rim strength (not spoke tension) determines radial stiffness (ie as bm0p700f has indicated), and spoke crossings affect torque stiffness (ie 2x/3x/4x are good for pedal and disc brake torque effects while 0x/1x are not good) ...

Hey kavitator, using 140kg (8000kms and still ok) were you expecting rim and/or hub flange cracking/failure, or even spoke fatigue/failure issues ...
Last edited by KLabs on Wed Feb 13, 2013 6:51 pm, edited 1 time in total.

styrrell
Posts: 167
Joined: Mon Apr 19, 2010 10:33 pm

by styrrell

A quick spoke question. Any opinions about Pillar X-TRA 1422 vs CX Rays? Quality, weight, aero, etc?

KLabs
Posts: 380
Joined: Wed Dec 01, 2010 4:29 am

by KLabs

Hi styrrell, have a look at kavitator and Eric posts regarding spokes ... http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=74564&start=3750, etc ...

Some posters are using MAC 424/360 spokes and Sapim now have a super spoke.

eric
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by eric

KLabs wrote:Hi kavitator, yes spoke tension (as does bracing angle and rim width) affects lateral stiffness (ie in preventing brake rub)


According to Damon Rinard's tests (http://sheldonbrown.com/rinard/wheel/index.htm) spoke tension doesn't affect lateral stiffness unless the spokes are loose enough that they become slack.

KLabs
Posts: 380
Joined: Wed Dec 01, 2010 4:29 am

by KLabs

eric wrote:
KLabs wrote:Hi kavitator, yes spoke tension (as does bracing angle and rim width) affects lateral stiffness (ie in preventing brake rub)

According to Damon Rinard's tests (http://sheldonbrown.com/rinard/wheel/index.htm" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;) spoke tension doesn't affect lateral stiffness unless the spokes are loose enough that they become slack.

Hi eric, does that mean by kavitator using 140kgf DS (28H hub/rim 3xDS race, 0xNDS laser) that he was able to improve NDS tension which would have allowed for the apparent improvement in lateral stiffness ... or do you think there is some other reasons ...

T1mbro
Posts: 2
Joined: Mon Dec 17, 2012 2:35 pm

by T1mbro

So a dilemma I need help with-

My current powertap pro+ is laced to a very old open pro rim. Pretty sure this is quite corroded and going to die soon so I want to build it into a new rim. It's 32h so should I go open pro again or is there something similar that would be better? It needs to be clincher as I use this wheel on the turbo too but if there is an opportunity to lighten it up I dont mind spending a bit extra use will be rainy days and turbos.

I WAS thinking about getting a quarq so that I could get some nice tubular wheels too but have been warned off and can't afford an SRM and new wheels so next option is a G3 built into a tubular rim. Im happy to build myself - not that experienced but if I mess it up i will send it to someone who is. I am 67kg and live in Devon so although heart says deem carbon rims head says get the lightest setup you can find. Is it possible to build a decent weight stiff set from a G3?

Eaglos
Posts: 1
Joined: Wed Feb 13, 2013 6:57 pm

by Eaglos

Greetings.

I have a friend's RS80 and I am trying to figure out where to place it
on Park Tool's tension chart. The wheel has steel bladed spokes which
measure 1.5 on narrow and 2.0 on the wide bladed side. Other than a
1.3 x 2.1, there is nothing close to what I measured. Looking at the
chart I saw that changes on the narrow side have greater impact
than those on the wide side and I tried to work something out
with that.

For example

A 1.4/2.3 spoke reads 117kg at "20", while a 1.4/2.6 reads 103kg.
That is around 7% kg decrease for every additional mm and a +1
on the chart reading (0,33 for every mm) to get as close to the
117kg as possible (115kg).

A 1.2/2.6 spoke reads 144kg at "20", while 1.4/2.6 reads 103kg.
That is around 19% decrease for every additional mm and a +3
on the chart reading (1.5 for every mm) to get the same kg.

Let's say that I aim at 131kg which is number 19 on the chart for 1.3/2.1.
Based on the above, I guesstimate that 19 for the 1.5/2.0 spoke would be
around 90kg and I should be aiming at 21-22 to get the desired kg.

Does the above make any sense? If not, has anyone here worked with RS80
before so he can provide me with the magic chart numbers in order to
be between the Shimano's 100-143kg recommendation?

Thank you.

bm0p700f
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by bm0p700f

Kavitor Klabs e.t.c the reason why more spoke tension helped in this case is not that increasing spoke tension imcrease lateral stiffness - IT DOES NOT DO ANY SUCH THING!!!!! Tension cannot increase the stiffness of the rim or the spokes, these are material properites determined by profile of the rim or spoke and the materials microstructure.

However increasing DS tension will increase NDS tension to when the high torque is being applied tot he rear wheel in a sprint say when the rim deflect it will have to deflect more to cause the NDs spokes to go slack. Once the NDS spokes (only some of them will go slack in a sprint and it will be the ones cloesest to the ground I think) the wheel lateral stiffness drops as these spokes are no longer holding the rim.

This is a different effect to saying spoke tension increaes wheel stiffness.

@Bearley. I use the Velocity A23 in builds quite alot and keep these in stock in most drillings. This rim has an ERD of 602mm. Give me the dimensions of you hub (or tell me what it is) and I can tell you what spokes lengths you need may be your existing spokes will be O.K. What spoke lengths do you have?

@T1mbro The velocity A23 is a good alternative to the Open Pro but has no eyelets (this not a problem though). If you want a rim that is 19mm wide then the Ambrosi Excellight is a good option as is the DT Swiss RR465. I personally think the RR465 is the best rim out of the lot, it is such a nice rim to build with and one of my favourites.
The Open Pro is the lightest rim of all the ones I have mentioned, it also the cheapest and it perfectly useable rim. I do not think they are the most durable but they are a bit lighter.

Eaglos, Anyone who uses the TN-1 has faced these issues. You have to use the TM-1 differently in these case. Decide by feel when the spokes are tensioned sufficently and then measure the deflection. You then have a deflection measurement to use to ensure the other spokes DS are evenly tensioned. NDS tension should also be even but the exact value will determined by getting the wheel dished.

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