A load of wheel questions

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brucelee
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Joined: 19 Feb 2009, 10:39am

A load of wheel questions

Post by brucelee »

The most pressing of which is :
1) Had a big creaking sound on my lht (UN55,FH-T780), checked the seatpost and all around the bottom bracket/crank bolts/chainring bolts all OK. There had previously been some play in the rear hub despite tightening the cones to the point where significant rotational friction was felt. I removed the axle and bearings and found play in the free hub with respect to the main hub body. By this I mean I could see (looking through the hole in the hub) movement of the entire free hub body not just the bit that carries the cassette. I don't have a 10mm allen key (will get one today). Is it likely to be just loose or is this a bigger problem. Never removed a free hub before.

2) OK, same hub.... When I first came to change the bearings, I noticed that the non-drive side had a plastic cage in it with fewer bearings than the drive side. Being a smart-arse I said to myself 'shimano are trying to save a few grams here for marketing purposes' and promptly put a full set of bearings in. The bearings are these (http://simplybearings.co.uk/shop/p37912 ... _info.html). The hub ran very nice and smooth. During a subsequent service, I noticed pitting on the non-drive side and so just rotated the cone. Now, I've come to service the hub again and the pitting is worse. Drive side is perfect. Is there something subtle I'm missing here ?

3) I've been building my wheels with A719's for the tourer and open pro's for the racer. I pretty much thought with the A719 that it was virtualy impossible to build a bad wheel cos it's sooooo stiff. Last year I replaced the rear rim on my tourer (the third on that wheel) and it just wouldn't stay strait. I then built a couple of race wheels with open pro's and had the same problem, they were a nightmare - nipples slacking off all over the place and spoke tensions going down all round. These rims looked different too - the stickers were on wonky and they had no wear indicator. Does anyone know if mavic made any changes to their production environment ? Or location ?

4) My racer got trashed in an accident - I'm guessing they'll write the bike off and I'll be able to build or buy new wheels. Not currently comfortable with open pro's as stated above so what alternative's are there ? I'm heavy so need to be built for strength. Quite fancy carbon rims but need to be able to take a high spoke tension and traditional lacing pattern. Also a decent braking surface. If no-one is aware of any specific mavic problems then I'd be inclined to be wary about the ALU material itself and so wouldn't be comfortable with rigida either assuming they're sourcing there materials from the same place.

Cheers,
Bruce.
pwa
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Joined: 2 Oct 2011, 8:55pm

Re: A load of wheel questions

Post by pwa »

You certainly need to get that large allen key and tighten the freehub body onto the hub shell. It would be unwise to continue using it until you have done that. It may well explain creaking.
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Gattonero
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Re: A load of wheel questions

Post by Gattonero »

1) before working more on that hub, try the bike with a spare wheel and reusing the cassette.
Perhaps the noise in not related to the hub at all
2) you've done a big mistake. Manufactures spend valuable time and skills to design a product, to alter it means looking for trouble. If I was you, I'll go back right away with the same bearing cage and not moving the cones from one side to the other. Also, they are design specific for each side.
FWIW, the new Shimano hubs with oversize axle seem to have done one step back in reliability :roll:
3) you need to be more specific with the hub you are using. The hub flange distance plays a very big role in giving spoke tension. Modern hubs then to have a big difference between Lh and Rh, with the spoke tension being dramatically low on the Lh.
Aside from perfect lacing and spoke forming and pre-stress of the built wheel, using low-strength and slow-cure threadlock on the Lh nipples gives great help
4) more than just the weight, is also the riding style. I.e. I'm not a superlight rider (72-74kg, or 11 1/2-12st.) yet I've never had to replace a spoke in my life. Even when racing Mtb on 28h wheels, never had problems. But I know other people racing on road, weighting a good 10kg less than me, that can thrash any wheel.
To be on the safe side, you can go with Mavic CXP33, or H+Son Archetype, or Hed Belgium. The last two, are more expensive and wider (can give problems of clearance on some frames/forks)
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
the snail
Posts: 334
Joined: 5 Aug 2011, 3:11pm

Re: A load of wheel questions

Post by the snail »

How are you measuring tension? Just wondering if you might be using a dodgy tension meter? If the rim is reasonably straight to start with, and you build it properly, I can't see why it would go out of true without something obviously failing, like broken hub, spoke, nipple, or cracked rim. The only issue I've heard of with open pros is cracking of rims by spoke holes - they don't like very high spoke tensions apparently.
hamster
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Joined: 2 Feb 2007, 12:42pm

Re: A load of wheel questions

Post by hamster »

For tough rims, have a look at Ambrosio Excellence.
nosmarbaj
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Location: West Berks

Re: A load of wheel questions

Post by nosmarbaj »

brucelee wrote:The most pressing of which is :
1) ... There had previously been some play in the rear hub despite tightening the cones to the point where significant rotational friction was felt. ...

You should not do this. If you have noticeable friction you are putting excessive force on the bearing surfaces and the balls as well, which might explain some of your subsequent problems. If it's not possible to adjust the cones to have no play and also minimal friction, then there is already something amiss that needs to be investigated.
Brucey
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Re: A load of wheel questions

Post by Brucey »

1) you need to check that the freehub and its seating are OK and you need to remount it so that it won't come loose again. You will need a bigger key than 10mm on a FH-T780 hub. The creak could be coming from anywhere.

2) You have almost certainly been running the hub adjusted way too tight. The correct adjustment on these hubs appears to be a bit loose, i.e. such that the hub has slight (but fairly obvious) play in the bearings when the wheel is out of the bike. The QR will compress the axle slightly and this should (when the adjustment is correct) eliminate the free play with minimum preload on the bearings. Shimano's instructions are just plain wrong and sadly there are a lot of people out there who don't know any better than to follow them. Loose balls in these hubs are fine BTW.

3) The country of origin is usually marked on Mavic rims. As well as France I have seen Mavic rims from Taiwan and more recently from Romania. The quality looked OK with all of them, and they built up fine. You could have another problem entirely of course but on the balance of probabilities it is most likely that there is something going wrong with the build rather than something wrong with the rim. I have not heard of other people having similar issues.

4) If you want light and strong, reasonable braking surface thickness, H plus Son archetypes are worth a look.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
brucelee
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Joined: 19 Feb 2009, 10:39am

Re: A load of wheel questions

Post by brucelee »

Turned out to be a loose freehub body
You certainly need to get that large allen key and tighten the freehub body
turns out to be 14mm - check out my tool improvisation :
WP_20160928_001.jpg

you need to remount it so that it won't come loose again
Does this mean use threadlock ?
not moving the cones from one side to the other. Also, they are design specific for each side.
I didn't swap the cones over, when I fitted the wheel I marked the cone so I could place the pitted section upwards, away from the loaded area. I'll still need a new cone though.
using low-strength and slow-cure threadlock on the Lh nipples gives great help
I toyed with the idea of thread lock but what happens when the wheels need adjustment ? Does the lock become ineffective once an adjustment has been made ?
As far as rims are concerned, I think they'll need to be double eyeleted, I'm a HEAVY rider (115KG).

You have almost certainly been running the hub adjusted way too tight
I'm sure I've got this nailed - always set them up slack and then gradually increase the QR tension till the play disappears. Having said that - at one point I was setting them up very slack and doing the QR up real tight because I was using a trailer that connected to the hub axle (will be doing a follow up post the the avenir mule 2 later today). I know that thing I said about the bearings cage sounds absurd but it's the only way to explain pitting on the non drive side only - that I can see. Also the axle gets visible thinner (in a step) on the non drive end.

Just in parting, with a new wheel build, before one brings the wheel up to tension, is there a rule of thumb about how many extra turns one should make to the nipples on the spokes coming out of the outer side of the flange ?

Cheers,
Bruce.
Brucey
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Re: A load of wheel questions

Post by Brucey »

a few thoughts;

- if the freehub body was loose it could be that the bearing loads were enormous once you were sat on the bike
- threadlock on the freehub body bolt isn't a bad idea but it won't make up for a bad seating
- threadlock on the NDS nipples doesn't usually inhibit later adjustment (except with the skinniest aero spokes perhaps) and it usually has some (rather than none) in the way of residual strength following adjustment.
- another possible explanation for the pitting is that one of the balls slipped out of place during assembly.

On the last of these points a good check is to finger-tighten the cones fully and to turn the hub; if the bearings are in there OK the hub ought to turn freely.

cheers
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Gattonero
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Re: A load of wheel questions

Post by Gattonero »

Agree for the above, and would advise again for low-strength threadlock. Normally are "222" "223" or "225" grade.
Do not use "240" or anything that starts with "24" or "27" as they are medium and high strength types. You won;t be able to move the spokes/nipples after.
With low-strenght you can still work after has set, albeit is -of course- a bit hard
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
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531colin
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Re: A load of wheel questions

Post by 531colin »

brucelee wrote:..........Just in parting, with a new wheel build, before one brings the wheel up to tension, is there a rule of thumb about how many extra turns one should make to the nipples on the spokes coming out of the outer side of the flange ?.....


I think that would be "none". Balancing the tension comes at the end.....balance the tension, stress the wheel, true the wheel....repeat....repeat
Brucey
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Re: A load of wheel questions

Post by Brucey »

if you build wheels so that all the 'pulling spokes' are on the outside, you can build with the same number of turns on every nipple. However if (as some folk do always, and shimano now advise for rear disc wheels) you build 'skew' i.e. with the inside spokes 'leading' on one side and 'trailing' on the other, there will be a small difference between the number of turns on the inside and outside spokes. This will vary with the bracing angle, (and therefore rim size).

So with the exact same number of turns on a skew built wheel, the inside spokes will all be very slightly slacker than the outside spokes. Often this pattern can persist into a completed wheel unless a correction is made.

The correction required is rarely more than about 1/2 turn, IME, and if the rim isn't quite straight, or is radially flexible, it'll be lost in the noise or built out anyway.

cheers
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pwa
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Re: A load of wheel questions

Post by pwa »

I once had an Ultegra freehub body that was loose. I tightened it pretty firmly (not OTT thread-stripping) and it never came loose again.
brucelee
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Re: A load of wheel questions

Post by brucelee »

Brucey wrote:- if the freehub body was loose it could be that the bearing loads were enormous once you were sat on the bike
This sounds like a good reason for me to get a new cone under warranty - the freehub shouldn't have slackened off. But it doesn't explain why pitting only occurred on the non-drive side.
Brucey wrote:On the last of these points a good check is to finger-tighten the cones fully and to turn the hub; if the bearings are in there OK the hub ought to turn freely.
cheers
The hubs turn perfectly smoothly and ride beautifully, I'm confident in my ability to set up a hub. This only leaves the question of me putting in a full set of bearings (11 instead of 9 with the retainer) caused the problem. This was on the non-drive side where the problem occurred.
Brucey wrote:if you build wheels so that all the 'pulling spokes' are on the outside, you can build with the same number of turns on every nipple.
Errrggg you've just blown my mind again - I remember shying away from wheel building years ago describing it as a 'black art' - then I had so many off the peg duds I gave it a try (with considerable success) but now I'm inclined to off load this to someone who just builds wheels. There are so many little details.....
Brucey
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Re: A load of wheel questions

Post by Brucey »

brucelee wrote:
Brucey wrote:On the last of these points a good check is to finger-tighten the cones fully and to turn the hub; if the bearings are in there OK the hub ought to turn freely.
cheers
The hubs turn perfectly smoothly and ride beautifully, I'm confident in my ability to set up a hub. This only leaves the question of me putting in a full set of bearings (11 instead of 9 with the retainer) caused the problem. This was on the non-drive side where the problem occurred....


I think you missed the point. You can set up the clearances in a 'bad bearing' and it might feel OK when you spin the wheel because there is no load on it. Inside the hub the balls are doing all kinds of crazy things.

My suggestion above is as a test of whether the bearing has a fundamental problem or not. If you have too many balls, balls the wrong size, some balls out of place, the wrong contact angles, the hub will bind in a rather unpleasant way when there is a slight preload (hence finger tightening the cones). If you are in any doubt, assemble everything without any grease (i.e. bone dry) and do the same test.

BTW you seem confident that you 'know how to set up hubs' but I wonder. If you assemble a modern shimano freehub with too much preload, the loading is actually higher on the LH bearing than the RH bearing as soon as you are sat on the bike. Things normally even themselves out because chain tension forces load up the RH bearing more than the left, but I have seen a few hubs where the left bearing suffered more than the right because the hub was set too tight.

It is very, very easy to set up these aluminium-axled hubs with too much preload on the bearings; the problem is that the QR skewer compresses the axle appreciably and this preloads the bearings horribly. The correct adjustment is so that there is a little slack in the bearings; this can be felt as movement of the rim when the QR is half-tight, but should disappear as the QR is fully tightened.

If you set any shimano QR hub (that uses adjustable cup and cone bearings) so that there is no free play in the bearings of a loose wheel, then the hubs are definitely set too tight. The hubs with aluminium axles are very much more prone to being overtightened than those with steel axles and the bearings suffer more for it too.

cheers
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