The ugly truth about hub width and wheel stiffness

El Caballo · May 12, 2006

Thylacine said:
Tell us - what spacing would we need to be at current 26er triangulation standards?

135mm TA/125mm QR for 29ers, and 125mm TA/115mm QR for 26ers, would get us back to the glory days of 1988 (standard 100mm QR non-disc hubs). I'll send you the spreadsheet.

Thylacine said:
You have to look at the whole picture, ElC. If you go too wide on the back, you start running into problems such as cross-chaining and heel clearance.

A wider bottom bracket spindle fixes that. I don't think the people who want/need burlier wheels are going to obsess about Q factor.

A better solution is going back to 6 or 7-speed rear clusters. With all the overlapping gears and cross-chaining issues, 9 speeds aren't very useful anyway. But forget I said that for now...it's foolish to joust more than one windmill at a time.

Guitar Ted · May 12, 2006

Bingo!

El Caballo said:
A better solution is going back to 6 or 7-speed rear clusters. With all the overlapping gears and cross-chaining issues, 9 speeds aren't very useful anyway. But forget I said that for now...it's foolish to joust more than one windmill at a time.

Solves the wheel issue. Solves the premature wearing out of drive train parts. Solves Q factor problems. Thank you!

This has the makings of a retro-grouch revolution. :rockon:

Cloxxki · May 12, 2006

A 140mm hub will fit a current 135mm frame with only minor hassle. Who hasn't used 135mm in a 130mm road or cx frame.
That 140mm hub with cassette space for just 6x9spd spacing, can have similar flange spacing as a current SS hub. Now how to get someone to build 6spd cassette's?
11-14-18-23-29-36 might allow many riders to ride 1x9.
2x9 with 29-42 should keep most happy.

How many does Suntour ask us to order for thei highest level cassette, in custom?
SRAM is doing cool things lately, would they be ready to beat Shimano to something new for once?

bcd · May 12, 2006

what we need to do is get a compromise on the fork arches.
see is they can make one to fit all. think that is possible?

I cut up a cheep casset that is pinned for the cogs i need.
I don't have this hub but use a WTB with a old screw on cog for a lock ring.
We don't need all those 9 rear cogs. for DH 4-5 XC might needa bail out
32 to make 6.

as for the front i came up with 120 b/c i can fit that on WB grooves now.
there is no reason 26ers can't just use what we do, if they want. Or let them use
the olds stuff.

135 seems like a better number for front. and if you are running 4-6 cogs on the rear
135 is fine too. rear is no problem there are hubs out there already.

CBBaron · May 12, 2006

jh_on_the_cape said:
you could get a pusley fork with 135 mm spacing.

The Pugsley fork would not be a good test subject. The fork is offset to the left to match the rear spacing. This allows you to build a dishless 9-speed disc hub, but requires a wheel built on a SS disc hub to be dished towards the disc side. Not the ideal wide symetric hub. Wheel strength on Puglsey's are not really a problem because the 65mm wide Large Marge is incredibly strong compared to normal rims.
However I'm sure you could get a custom builder to build a 135mm spaced rigid fork. Then you could use a SS disc hub for a test. For rear wheels tandems have several extra wide hubs already available you just need a new frame.
So maybe a new hub standard is not needed you a new frame/fork standard?
Craig

GlowBoy · May 12, 2006

CBBaron said:
The Pugsley fork would not be a good test subject. The fork is offset to the left to match the rear spacing. This allows you to build a dishless 9-speed disc hub, but requires a wheel built on a SS disc hub to be dished towards the disc side.

It's true the wheel has to be dished towards the disc side - if you intend to run a 3.7" Endomorph tire. But I'm pretty sure you can still squeeze in a regular 29" tire mounted on a conventional rear wheel. Not a great long-term solution (besides looking funny, the handling might be odd since the wheel's plane of rotation is slightly off the steering axis), but I bet it would work for testing purposes.

Law · May 12, 2006

Cloxxki said:
A 140mm hub will fit a current 135mm frame with only minor hassle. Who hasn't used 135mm in a 130mm road or cx frame.
That 140mm hub with cassette space for just 6x9spd spacing, can have similar flange spacing as a current SS hub.

It is only a problem if you are using a full suspension frame design where the bearing could have an unintended load put on them. Not sure how likely that would be. Obviously some designs this wouldn't be an issue. I am thinking more in terms of a four bar or faux bar linkage design.

I am just trying to be difficult, don't mind me.

El Caballo · May 12, 2006

bcd said:
what we need to do is get a compromise on the fork arches.
see is they can make one to fit all. think that is possible?

I think so. XC riders and weight weenies will be happy with the current standard, so there's no need to please anyone who wants less than 5-6" of fork travel. This is a standard for AM, FR, and DH.

Given that, we can go big. 165mm is nice because it doubles our stiffness, but anything 150mm and over is worthwhile.

Potential issues with 150mm-165mm crowns and hubs:

-Downtube clearance with single crown forks. The Reba has paved the way for more room here, but 165mm fork crowns would still have to be taller or more sloped if we want them to spin around.
It's not a big deal...with 29" wheels, you've got plenty of stanchion to work with, and can just make the lowers a bit shorter to compensate.
Of course, the other alternative is to give up on bar spins, go as short as possible, and make nice little padded/contoured bumpers like they do with dual-crown forks. I personally don't care about bar spins, just knee clearance, but I'm open to input here. Thoughts?

-Crowns must be slightly beefier, and arches on non-inverted forks must be beefier. Not a big deal...the riders will be saving so much weight on the rim that they won't mind a couple extra ounces of non-rotating weight.

-Axle diameter. Does 20mm provide enough stiffness under disc braking if we bump the width up from 110mm (current standard) to 165mm? I don't know enough to answer that. I'm sure 30mm would be stiffer, but I don't know if it's necessary, or if it makes the wheel bearings too expensive.
However, I'm pretty sure that a 165mm QR isn't going to work. No big deal...this is a standard for 5" travel and up.

-More offset. AM/FR/DH uses slacker head angles...no one will be running 6" forks at 72 degrees. It would be nice to run 66-68 degree HA on a 29er and not have people complain about steering a truck. (I don't personally care, but I come from a motorcycling background, where two wheels weigh 300-500 pounds.)

El Caballo · May 17, 2006

Flange spacing larger than 79mm?

I've been looking for the hub with the largest flange spacing, front or rear, as a test mule. mikesee courteously pointed me at the DT Swiss spoke length calculator, which contains measurements for hundreds of different hubs.

The 135mm Surly non-disc SS rear hub has the largest flange spacing I can find: approximately 79mm.* This only gets us 9mm over a non-disc XT (~70mm). An extra 14% of stiffness would help, but it's not the quantum leap we're looking for.

Does anyone know of a rear SS hub with wider spacing? Or any hub, for that matter? Do I have to go looking for motorcycle hubs, or a lathe?

* The DT Swiss calculator measures distance to the inside of the flange: my figures are to the center of the flange. So I've added 2mm to the DT figures to compensate.

dgdixon · May 17, 2006

I agree with the point regrding the added strength of wider flange spacing, but a new hub standard is a ways off, and in the mean time there are ways to build 29er wheels as "stiff" as 26" wheels.

While a quality wheel build makes a huge difference, from strictly hardware perspective (spoke length and angle) my current bike uses two different approaches to compete with 26" wheel strength. The rear wheel is built with a Rohloff hub which has a big flange that builds with spokes the same length as a 26" wheel, and it has the wide flanges of a single cog and no dish, so it can be built as strong or stronger than most geared 26" wheels. The front is a deep aero ZIPP 505 carbon rim, which shortens the spoke length and increases the spoke angle.

-David

Cloxxki · May 17, 2006

Whatever happened to (Shimano's?) idea to cross spokes over? Spoke holes in the rim offset to the other side for optimal angle. Did it work, is it still used, does it have a place on AM wheelsets? It will require a dedicated rim extrusion, but I think it might help get more out of the current hub standards?

bcd · May 17, 2006

El Caballo said:
I've been looking for the hub with the largest flange spacing, front or rear, as a test mule. mikesee courteously pointed me at the DT Swiss spoke length calculator, which contains measurements for hundreds of different hubs.

The 135mm Surly non-disc SS rear hub has the largest flange spacing I can find: approximately 79mm.* This only gets us 9mm over a non-disc XT (~70mm). An extra 14% of stiffness would help, but it's not the quantum leap we're looking for.

Does anyone know of a rear SS hub with wider spacing? Or any hub, for that matter? Do I have to go looking for motorcycle hubs, or a lathe?

* The DT Swiss calculator measures distance to the inside of the flange: my figures are to the center of the flange. So I've added 2mm to the DT figures to compensate.

I have that hub on my dirt jump/street bike. yeah, its W I D E. i like it.

I have never seen one wider. i can get you some mesurements/pics

on angles if you would like.

heavyg · May 17, 2006

xtr spokes

XTR 26" wheels from last year (and this year, too, I believe) have the crossover spoke arrangement. Very neat looking, and they are fairly strong for a very lightweight wheelset. I don't think those wheels are quite beefy enough for AM, at least under 215# riders like me, anyway. I replaced them with Crossmax XLs. But the concept may be worthwhile to look at using fatter spokes and/or burlier rim?

It looked to me like the '07 XTR wheels are going away from this design. My biggest beef with it is that it is a pain to true the wheels. With the nipples at the hub there is poor access for the spoke wrench, and the lacing arrangement can make it a little confusing to make sure you have the correct spoke in on the hub end. (The drive side of the rear wheel is radially laced)

El Caballo · May 18, 2006

heavyg said:
XTR 26" wheels from last year (and this year, too, I believe) have the crossover spoke arrangement. [...] But the concept may be worthwhile to look at using fatter spokes and/or burlier rim?

It probably adds some stiffness, though I'd have to measure one to see how much, and I see a theoretical maximum of about 23% based on my estimates. (If anyone has one and is willing to take a couple quick measurements, PM me.)

However:

1) It seems like it would be at least as hard to persuade rim makers to create a totally new rim design and standard (new extrusions, new drilling methods) as it would be to persuade fork makers to simply widen crowns and arches.

2) It seems like it would be even harder to persuade hub makers to create a totally new hub design and standard (spokes pulling from the hub) as it would to persuade them to simply widen existing designs.

It's funny that Shimano can do that redesign for a single model year of their highest-end (and worst selling) product line, and can recast their cranks every couple years for completely cosmetic reasons -- but widening and reinforcing an existing hub design to be wider is "too difficult", "too much tooling cost", etc. No, it's just inertia.

Fortunately, we can overcome inertia.

(bcd: thanks for the offer, but you don't need to. I already got the data from Surly's website.)

Thylacine · May 18, 2006

1) Not if you hassle manufacturers that do CNC'd crowns rather than forged.

2) Making a wider front hub is easy. Anyone with a lump of billet and a Lathe can do it. The hard part is getting "1)" done first. I've hassled WB and Jake from Project321 and I are working on something (or actually more like I'm trying to convince him of something)

3) It's not inertia, it's percieved market. Niche products come from niche manufacturers, and I hate to break it to yas, Shimano is all about volume. Ignore them if you want a new standard to take off, hassle the people who would be more open to the idea of new hub widths, like White Ind, Paul, etc.

古強者死神 · May 18, 2006

I just thought I would add my discussion that I had about this with my LBS.

They sell the GF 29" bikes and they have told me that since they started selling those bikes they have not seen any increase at all in wheel damage.

That in additon to the multiple statments above from 29" wheel owners stating how they have not damaged a wheel on there 29" bike or noticed any increase in its prone'ness to get damaged leads to belive that while the math might add up right for you, its real world value is nil.

One thing that struck me too is the fact 29" wheels have a larger contact surface with the ground. So at any given time when the wheel lands on a surface the force is applied to more of the rim/tire than a 26" would and also it takes less a shock from bumps and things in the road due to its larger angle.

The exeption to that would be if you landed on somthing small like a big rock with an edge where the whole wheel doesnt land but instead only only part of it, in that case the larger surface area of the wheel cant be used.

Still tho keep all of the above in mind it really distills alot of your testimony.

Cloxxki · May 18, 2006

Interesting idea!
Also, the longer spokes and larger rims might flex where small wheel would bend, partly or completely compensating to make wheels last about as long as small ones.Still, we're talking here about 10% dimensional differences. Maybe 15% for spokes. Can't expect what used to work to now simply fail in all cases.

mgersib · May 18, 2006

古強者死神 said:
They sell the GF 29" bikes and they have told me that since they started selling those bikes they have not seen any increase at all in wheel damage.

That in additon to the multiple statments above from 29" wheel owners stating how they have not damaged a wheel on there 29" bike or noticed any increase in its prone'ness to get damaged leads to belive that while the math might add up right for you, its real world value is nil.

Still tho keep all of the above in mind it really distills alot of your testimony.

I have to concur with your dealer. The shop I ride for sells more 29ers than 26-inchers these days, and there have been no substantial issues with wheel weakness to speak of. We've got guys who rip that are an easy 250lbs on them too, so it hasn't been weight-dependent either.

I'm only 160lbs, but ride pretty aggessively, jump a fair bit, and occasionally throw in the messed-up sideways landing, and even so, I've had absolutely no issues with any of my 29er wheels. Other than one wheel that I had to retension after 2 months of riding, it's been completely smooth sailing for me on 29er wheels, so I really don't have an overwhelming need for stiffer/stronger wheels for xc use.

mikesee · May 18, 2006

mgersib said:
I have to concur with your dealer. The shop I ride for sells more 29ers than 26-inchers these days, and there have been no substantial issues with wheel weakness to speak of. We've got guys who rip that are an easy 250lbs on them too, so it hasn't been weight-dependent either.

I'm only 160lbs, but ride pretty aggessively, jump a fair bit, and occasionally throw in the messed-up sideways landing, and even so, I've had absolutely no issues with any of my 29er wheels. Other than one wheel that I had to retension after 2 months of riding, it's been completely smooth sailing for me on 29er wheels, so I really don't have an overwhelming need for stiffer/stronger wheels for xc use.

Matt-

I think what we're getting at with all of this is a wider standard for AM/FR/DH bikes. It's true that XC wheels can be built 'strong enough' as is, although your Mav hub is better than the norm because it's flanges are so wide. Still, a wider standard would also benefit XC riders--they'd be able to get a lighter wheelset with the same (or more) stiffness than their current setup.

Cheers,

MC

Thylacine · May 18, 2006

mgersib said:
I have to concur with your dealer. The shop I ride for sells more 29ers than 26-inchers these days, and there have been no substantial issues with wheel weakness to speak of. We've got guys who rip that are an easy 250lbs on them too, so it hasn't been weight-dependent either.

I'm only 160lbs, but ride pretty aggessively, jump a fair bit, and occasionally throw in the messed-up sideways landing, and even so, I've had absolutely no issues with any of my 29er wheels. Other than one wheel that I had to retension after 2 months of riding, it's been completely smooth sailing for me on 29er wheels, so I really don't have an overwhelming need for stiffer/stronger wheels for xc use.

I don't really see the opinions of one, two or even 20 bike shops as having scientific merit from a design perspective. Whether it's an issue now or not, the 29er market is pretty amazingly small, and it remains that 29er wheels have less triangulation and ARE weaker than 26er wheels. That's not annectdotal, that's scientific proof.

I believe in improving things isn't based solely on practicality. I mean, we all rode 30lb hardtails at one stage (well, some of us did) and were perfectly happy. Heck, the advent of 29er wheels wasn't a response to a practical problem itself, so I fail to see how you can take a 'if it ain't broke, don't fix it' approach when clearly there are improvements to be made.

I want to see 29er wheels which are as strong as 26er wheels and more importantly are approching them in rotational weight. Anything that makes bikes better is a good thing in my book.

The ugly truth about hub width and wheel stiffness

El Caballo

Guitar Ted

Cloxxki

bcd

CBBaron

GlowBoy

Law

El Caballo

El Caballo

dgdixon

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Cloxxki

bcd

heavyg

El Caballo

Thylacine

古強者死神

Cloxxki

mgersib

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mikesee

Thylacine

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