New wheel...Rapid loss of spoke tension

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Edwards
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Re: New wheel...Rapid loss of spoke tension

Postby Edwards » 7 Apr 2011, 8:50am

FW I think we have used the same wheel building diagram :oops:
Keith Edwards
I do not care about spelling and grammar

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ferrit worrier
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Re: New wheel...Rapid loss of spoke tension

Postby ferrit worrier » 7 Apr 2011, 9:27am

Edwards wrote:FW I think we have used the same wheel building diagram :oops:


:lol: :lol: :lol:
Percussive maintainance, if it don't fit, hit it with the hammer.

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531colin
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Re: New wheel...Rapid loss of spoke tension

Postby 531colin » 7 Apr 2011, 10:54am

Mick F wrote:
It must be that my Campag Chorus on Rigida Chrina is unusual.


CORRECT!
Campag. 10 speed has the most dish of any wheel you will regularly build, and 2mm difference is appropriate.
Shimano 10 speed road has less dish, mountain stuff less than shimano road.

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georgew
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Re: New wheel...Rapid loss of spoke tension

Postby georgew » 8 Apr 2011, 3:08pm

Mick F wrote:Glad you're sorted!

I didn't worry about dishing and respective tension, because the spoke lengths were correct. You tighten them up to the same position on the threads and the wheel should be just about correct. All you need to do is tighten them evenly. Dishing should take care of itself as spoke length is correct and if you use plain gauge on the drive side and DB on the left, the tension comes in ok with the wheel true and dished.


I thought someone might find this little tool handy. It was thought up by a blind friend of mine and his instructor at the Institute for the blind in Birmingham some years ago when he was doing his City of Guilds. Unlike other spoke tools this one holds the nipple being threaded securely and places each nipple at exactly the same point on each spoke thread. It should only take around ten minutes to make from a spare spoke. Cut off the fluted section of the nipple and thread down to the end of the spoke thread using Superglue/Aaraldite to secure. Cut off the thread leaving 4mm protruding. Shape the spoke as shown and use shrink wrap to cover the handle part. When using, thread on the nipple and place through hole, threading onto the spoke until it stops. Hold threaded nipple on spoke and unwind tool.

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spanner
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Re: New wheel...Rapid loss of spoke tension

Postby spanner » 9 Apr 2011, 12:40pm

i bought a 1988 peugeot aspin racer last year which had been sitting in a garage for years, the rear wheel had one of those helical freewheel hubs on it and also the rim was twisted so took a pair of wheels off a bike i dont use just now and stripped them and cleaned them up and rebuilt them with new db spokes(sapim) and havent had any problems with the spokes pinging.
the thing with wheel building is everyone builds wheels different the way i learned was through the wheel building dvd from alf webb at bike inn who runs bike mechanic and wheel building courses in wragg marsh in spalding lincs which shows how to build a mtb rear wheel a sputnik rim on a hope triglide hub using sapim stainless steel spokes.

BigG
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Re: New wheel...Rapid loss of spoke tension

Postby BigG » 9 Apr 2011, 8:35pm

Mick Fs spoke length calculation published above above raises an issue with regard to spoke tension. The tension of each set of spokes (drive side and near side) is inversely proportional to the offset of the flange from the centre of the hub. This makes the horizontal component of the spoke tension the same for each set of spokes. It is this equality of the horizontal component of the tension that holds the rim in position. With flange to centre distances of 17 and 37 mm (10 speed Campag, I think), the drive side spokes have to be tensioned to more than double the near side ones. This gives tensions of perhaps 120 kgf on the drive side with only 55 kgf on the near side - or a massive 175 kgf on the drive side if he insists on the recommended (by whom?) minimum of 80 kgf on the near side! Colin 531s recommendation of 120 and 80 kgf would certainly not apply in Mick Fs case. This is one of the penalties of 10 speed cassettes - and the relatively large Campag sprocket spacing.

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Mick F
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Re: New wheel...Rapid loss of spoke tension

Postby Mick F » 9 Apr 2011, 8:53pm

I have actually got no idea what the tension is on my rear wheel, let alone my front wheel.
(2006 Campag Chorus/Rigida Chrina 32f 36r)

It was one of the reasons I thought about buying a Park TM-1, but then again, does it matter?
My wheels are true and seem to be standing up to my "punishment", so what the heck ........



....... but I would like to know.


BigG wrote:and the relatively large Campag sprocket spacing.
BTW, 10sp, 9sp and 8sp are basically the same width.
Mick F. Cornwall

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531colin
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Re: New wheel...Rapid loss of spoke tension

Postby 531colin » 9 Apr 2011, 11:13pm

In practice, its never necessary to go above 120 to 130kgf on the driveside to get 70 to 80kgf on the nearside on road wheels.
MTB stuff regularly runs 120/80kgf.
the horizontal component (moment?) of the tension sounds right, but its too late in the day to think about that!

billynibbles
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Re: New wheel...Rapid loss of spoke tension

Postby billynibbles » 10 Apr 2011, 4:19pm

Just a thought - could it be that they were constructed in a very cold shed, and now that warmer weather's here, the spokes get longer with expansion, or is this offset by the rim getting bigger too?

I've noticed that the spokes on my nearly new Dahon Matrix with disc brakes seem to come loose as a matter of course, but then disc brakes put a whole new set of rotationary tensions on spokes compared to rim.
National Standard Cycling Instructor. Brompton 16" folder, Dahon Matrix 26" folder, Ridgeback 700C Hybrid, Moulton De-Luxe 'doer-upper' project

spanner
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Re: New wheel...Rapid loss of spoke tension

Postby spanner » 10 Apr 2011, 9:32pm

billynibbles wrote:Just a thought - could it be that they were constructed in a very cold shed, and now that warmer weather's here, the spokes get longer with expansion, or is this offset by the rim getting bigger too?

I've noticed that the spokes on my nearly new Dahon Matrix with disc brakes seem to come loose as a matter of course, but then disc brakes put a whole new set of rotationary tensions on spokes compared to rim.

the fact the wheels were built in a very cold shed wouldnt make any odds as th whether the spokes expanded in hot weather or not.
i built a set of wheels for a racer i intended restoring and the wheels sat in the shed all winter after they were built then fitted to one of my other bikes in order to bed them in before i started doing the restore on the bike the wheels were intended for, during over 200 miles i had no problems with these wheels of spoke twanging.
put the front wheel of my nigel dean out of true today on a club run went over the edge of the road into the camber and the wheel was rubbing on the road edge and managed to get the wheel back onto the road surface so will have to put it into the jig and give it a retrue it doesnt seem to be too far out of true though.

bakaman
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Re: New wheel...Rapid loss of spoke tension

Postby bakaman » 5 Jun 2011, 2:48pm

I have had the same experience. Self built Tiagra FH4500 with Chrina rim, ACI Alpina DB spokes, 294mm both sides. 3 cross, all new pattern.

Build OK, destressed OK, tension checked against pro built wheel. Fantastic.

5 miles into the commute and ALL the spokes were loose. No grease or lube used during build.

Anyway, retensioned and trued, much better except that one or two spokes would loosen off every few days. Added tension to all spokes, and less loosening - but some, but the worst is spokes breaking at the elbow. I can almost guarantee one will go every 75-100 miles!

Difficult to work out what it is. Could it be ACI DB spokes with the 2.5mm hub hole allowing too much play, leading to stress failure? Wondering about using brass washers to bring the elbowcloser to the side wall of the flange. Some people talk about punching the spoke flush with the hub, not sure which way to go. Any help much appreciated.

PS, notable elongation of hole in hub - could that be a clue?

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531colin
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Re: New wheel...Rapid loss of spoke tension

Postby 531colin » 5 Jun 2011, 10:25pm

bakaman wrote:I have had the same experience. Self built Tiagra FH4500 with Chrina rim, ACI Alpina DB spokes, 294mm both sides. 3 cross, all new pattern.

Build OK, destressed OK, tension checked against pro built wheel. Fantastic.

5 miles into the commute and ALL the spokes were loose. No grease or lube used during build.

Anyway, retensioned and trued, much better except that one or two spokes would loosen off every few days. Added tension to all spokes, and less loosening - but some, but the worst is spokes breaking at the elbow. I can almost guarantee one will go every 75-100 miles!

Difficult to work out what it is. Could it be ACI DB spokes with the 2.5mm hub hole allowing too much play, leading to stress failure? Wondering about using brass washers to bring the elbowcloser to the side wall of the flange. Some people talk about punching the spoke flush with the hub, not sure which way to go. Any help much appreciated.

PS, notable elongation of hole in hub - could that be a clue?


Working from the bottom up;
The spoke elbow always forms a radius in the softer hub flange...is that what you see? The hole through the flange should stay round.
Spokes breaking at the elbow is fatigue...premature fatigue is caused by failure to cold set the bend and stress-relieve the wheel.
Spokes coming loose is inadequate tension....I lubricate R. driveside only between nipple and rim, you can't get them tight enough dry. I lubricate both sides front, but not nearside rear.
Lots of information here http://forum.ctc.org.uk/viewtopic.php?f=5&t=49702&hilit=spokes&start=30

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meic
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Re: New wheel...Rapid loss of spoke tension

Postby meic » 5 Jun 2011, 11:30pm

Well I had the same problem though not quite as severely.
An improvement which is possible and that I did with some effect, is to replace your drive side spokes with something thicker, either plain or single butted and this will allow you to put more tension into the left spokes, also the drive spokes will have less elongation under stress which will help keep the spokes on the other side of the rim under tension.
The theory may not be brilliant but it does help.

You could possibly get some 2mm shorter while you are at it, though you failed to mention if you are using 32 or 36 spokes.
Yma o Hyd