Floppy wheels

by Gizmo_   April 1, 2014  

Yes, Roaders... I have a flaccidity problem.

2014 Boardman Team CX. When you lean on one side of the bars and then the other, the front wheel visibly deflects - maybe half an inch, maybe even more. You can do that same thing with the rear wheel (with more difficulty). This strikes me as inefficient, and also makes it a faff to line up the discs.

Is there an easy way to increase the tension in the wheels? Obviously - get a spoke tool and twiddle. But apart from that, are there any top tips?

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All wheels flex as this is what gives them tensile strength, they need to do this or that would break, they would also be very uncomfortable if too rigid. If you want a bomb proof stronger wheel then you will have to up the spoke count and use a standard lacing pattern.

posted by MKultra [197 posts]
1st April 2014 - 16:03

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MKultra wrote:
All wheels flex as this is what gives them tensile strength, they need to do this or that would break, they would also be very uncomfortable if too rigid. If you want a bomb proof stronger wheel then you will have to up the spoke count and use a standard lacing pattern.

Rubbish.

Some of the stiffest wheels I own have 18 or 20 spokes at the front. The worst pair I have has 32 (budget crap thrown on a budget bike, granted). Half an inch is a LOT for any wheel. If that's normal I'd love to see how wide you set your brake calipers to avoid rub. It's also very odd that the front wheel deflects more than the rear, it's normally the other way round.

Mavic Ksyrium SLS, Crossride for the MTB and Fulcrum Racing 0. Low spoke count - stiff - bombproof.

posted by ajmarshal1 [266 posts]
1st April 2014 - 16:56

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ajmarshal1 wrote:
MKultra wrote:
All wheels flex as this is what gives them tensile strength, they need to do this or that would break, they would also be very uncomfortable if too rigid. If you want a bomb proof stronger wheel then you will have to up the spoke count and use a standard lacing pattern.

Rubbish.

Some of the stiffest wheels I own have 18 or 20 spokes at the front. The worst pair I have has 32 (budget crap thrown on a budget bike, granted). Half an inch is a LOT for any wheel. If that's normal I'd love to see how wide you set your brake calipers to avoid rub.

Mavic Ksyrium SLS, Crossride for the MTB and Fulcrum Racing 0. Low spoke count - stiff - bombproof.

It's not rubbish.

Why not email Pete Matthews and tell him how wrong he is?

posted by MKultra [197 posts]
1st April 2014 - 16:57

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So half an inch of deflection is normal? And my radial laced 16 spoke front wheel should be noodly and fragile? 3000+ miles and no brake rub says different.

There's a hell of a lot more to wheel stiffness than simple spoke count.

posted by ajmarshal1 [266 posts]
1st April 2014 - 17:08

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ajmarshal1 wrote:
So half an inch of deflection is normal? And my radial laced 16 spoke front wheel should be noodly and fragile? 3000+ miles and no brake rub says different.

There's a hell of a lot more to wheel stiffness than simple spoke count.

No it's the build and the spoke count.

The simple fact remains though that for certain applications a traditional build with a good quality rim and higher spoke count lends greater strength, especially so for a commuter, tourer or cross bike used as such.

You also have to take into account rider weight and sprung weight on the bike which is an issue with low count wheels.

But hey ho you go ahead you get arsey and take offence because you feel affronted by the idea that your flashy wheels are not the pinnacle of wheel technology to all men.

posted by MKultra [197 posts]
1st April 2014 - 17:15

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MKultra wrote:
ajmarshal1 wrote:
So half an inch of deflection is normal? And my radial laced 16 spoke front wheel should be noodly and fragile? 3000+ miles and no brake rub says different.

There's a hell of a lot more to wheel stiffness than simple spoke count.

No it's the build and the spoke count.

The simple fact remains though that for certain applications a traditional build with a good quality rim and higher spoke count lends greater strength, especially so for a commuter, tourer or cross bike used as such.

You also have to take into account rider weight and sprung weight on the bike which is an issue with low count wheels.

But hey ho you go ahead you get arsey and take offence because you feel affronted by the idea that your flashy wheels are not the pinnacle of wheel technology to all men.

Oh I'm not getting arsey, just pointing out the huge flaw in your argument. I note that you added the build contributes now in addition to spoke count and pattern, which is exact;y what I was saying. If you think half an inch of deflection is normal, then your standards are remarkably low. I'm simply going by my own experience of owning a number of wheelsets, factory and handmade. I have NEVER owned a wheel, Road or MTB that deflected that much, budget or high end.

The fact remains that there is more to stiffness than simple spoke count, there are a multitude of contributing factors. Otherwise at a simple level, my Fulcrum 7s would be stiffer than my zeros, which they aren't. Likewise my Crossrides and Hopes, which are on a level playing field despite my Hopes being 32 spoke. This is all taken from riding them. I've ridden HED Carbon tubs laced 24 to 28 that had more flex than chinese carbon tubs that were 20 / 24.

Mind, not that any of this helps the OP. Other than he has a really poor front wheel that needs looked at.

posted by ajmarshal1 [266 posts]
1st April 2014 - 17:40

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Gizmo... your timing sucks!

My cycle 2 work window opened today... guess what my choice was? Fortunately, I'm off work after breaking myself a couple of weeks ago, so couldn't access the codes to order my Boardman CX Team 2014.

Half an inch is a huge amount of deflection, but I'd have thought almost bearable as they are disc brake wheels.

The only solution is to get the wheels completely rebuilt. Worst case scenario is that it'll cost 30-40 quid per wheel. You might be able to get it done cheaper.

I'll give it a go myself. It'll give me something to do in between getting the bike and being physically able to ride again.

My eyes prefer Celeste, my bum prefers titanium.

Jack Osbourne snr's picture

posted by Jack Osbourne snr [304 posts]
1st April 2014 - 18:51

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QR's may not be tight enough, or there may be play in the bearings.

SHUT UP LEGS

ITU Aeronautical Eng.

posted by Efe M. Balli [13 posts]
1st April 2014 - 19:42

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Half an inch sounds like a lot of deflection to me. My bike has very little clearance so there's no way I would be able to ride it with that amount of wheel deformation without significant rubbing.

FYI, there was a nice interview with Paul Lew from Reynolds regarding the components that make up wheel stiffness on road.cc last week:

"According to Lew, spoke stiffness and spoke count are also responsible for 40% of wheel stiffness, but spoke crossing patterns and spoke tension don’t have a significant impact on this variable.

“Increasing the spoke count in a front wheel from 16 spokes to 20 spokes will increase the wheel's resistance to deflect laterally by approximately 30%. Increasing the spoke diameter and profile from a 2.0/1.8/1.5mm triple-butted spoke to a straight-gauge 2.0mm spoke will increase the wheel stiffness approximately 35%. The combination is additive, so increasing the spoke count from 16 to 20 spokes and the spoke diameter to a 2.0mm straight-gauge spoke will increase overall wheel stiffness by 65%.”

He says that the belief that a crossing spoke pattern will increase vertical deflection while minimising lateral deflection is incorrect; it will typically increase both. The final component of the wheel, the rim, determines 20% of wheel stiffness, says Lew. The material used and the section aspect ratio both come into play here, the section aspect ratio being the more important."

BTW, Rolf only uses 14 in front and 16 rear for their Vigor Alpha wheels and no one complains about sig deflection and excessive spoke breakage. Sounds like something's wonky with your wheelset IMO.

Melancholy is incompatible with bicycling. ~James E. Starrs

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posted by movingtarget [133 posts]
1st April 2014 - 19:56

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How, exactly, are you measuring this? Are tyres fitted? My wheels 'feel' like they move a lot if I do what you say, but at least half is tyre movement ( and that is with 23's at 90psi, the rest is in the handlebars (as far as I can tell). If you are having trouble lining your discs up to cope I would suggest that you have bearing play, which is something else entirely. Normally adjustable too...

Currently going slower than I'd like...

posted by stealth [177 posts]
1st April 2014 - 20:00

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Efe M. Balli wrote:
QR's may not be tight enough, or there may be play in the bearings.

Efe, these are disc brake wheels. Either of those factors would cause the disc rotor to rub, or most likely, jam on the brake pads.

My eyes prefer Celeste, my bum prefers titanium.

Jack Osbourne snr's picture

posted by Jack Osbourne snr [304 posts]
1st April 2014 - 20:04

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The Team CX's front brake is only slightly above the axle. I think the wheel can wobble in the bearings without actually having the disc touch the brake pads. Put another way, half an inch of flex (1.27 cm) at the top of the rim(31.1 cm from hub) will result in 1.27 x 31.1/5= 2.04 mm of movement on a point 5 cm above the rim, that is, where the pads touch the disc(assuming the wheel itself is rigid). 5 cm is the vertical distance from the hub to the brake pads and may be incorrect, but you get the idea.
Still worth checking the QR's and bearings.

SHUT UP LEGS

ITU Aeronautical Eng.

posted by Efe M. Balli [13 posts]
1st April 2014 - 20:46

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Efe M. Balli wrote:
The Team CX's front brake is only slightly above the axle. I think the wheel can wobble in the bearings without actually having the disc touch the brake pads. Put another way, half an inch of flex (1.27 cm) at the top of the rim(31.1 cm from hub) will result in 1.27 x 31.1/5= 2.04 mm of movement on a point 5 cm above the rim, that is, where the pads touch the disc(assuming the wheel itself is rigid). 5 cm is the vertical distance from the hub to the brake pads and may be incorrect, but you get the idea.
Still worth checking the QR's and bearings.

A great engineers answer! I see where you're coming from theoretically...

However...You don't get +/- 2.04 mm tolerance with BB5's. The rotor would rub like feck or not turn at all. I also think the centre point of the brake track is more like 70mm from the hub centre, therefore making the wobble even greater at that point.

That's why I dont think its the bearings or QR... you're right though that it is still worth checking.

My eyes prefer Celeste, my bum prefers titanium.

Jack Osbourne snr's picture

posted by Jack Osbourne snr [304 posts]
1st April 2014 - 22:44

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I've just reread the original post... and am now confused. It could be any of the above.

I do still believe that bearing play is the less likely culprit as BB5 brakes can be a nightmare to set up all by themselves.

My eyes prefer Celeste, my bum prefers titanium.

Jack Osbourne snr's picture

posted by Jack Osbourne snr [304 posts]
1st April 2014 - 22:57

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I can't get 1/4 of an inch deflection in my wheels. Get them to your LBS.

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posted by pakennedy [45 posts]
2nd April 2014 - 11:49

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