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PostPosted: Sun Jun 12, 2016 5:32 pm 
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I want to increase the lateral stiffness of my rear Bontrager Aeolus 5 TLR carbon clincher 24H wheel. I don't know exactly which spokes the wheel comes with from the factory but the Bontrager site says they are 14/17/14 black/aero bladed "Stacked Lacing - Provides a better spoke bracing angle for a stiffer wheel". They are probably DT spokes since the hub internals come from DT.

The question is, if I want to rebuild the wheel with heavier gauge spokes while retaining the aero/bladed profile how much stiffer can the rear wheel realistically be? I am hoping for a significant improvement which to me would mean at least 25% stiffer although I obviously don't have a way to measure that.

If this rebuild plan will get me what I want can someone please recommend a good spoke option? I was looking at the DT Aero Speed or Aero Comp…

FYI, this is why I want to stiffen up the rear wheel viewtopic.php?f=3&t=139714 and I figure 24 new spokes and a rebuild charge will be a lot cheaper than a set of Lightweight carbon clinchers :wink:


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PostPosted: Sun Jun 12, 2016 5:50 pm 
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if they are 14/17/14 bladed they are likely to be DT aerolite. If you need J bend spokes, be careful as the aerospeed needs a slotted hub, the aerocomp will go through any hole instead. Either are not very easy to find in all sizes. Things get even more complicated if you need straight pull spokes, as they are even harder to find in all sizes.

Hard to quantify how much stiffer they will be, but they will be stiffer. The drive side is the weak side of the wheel and the one you might want to rebuild first (cheaper than doing the all wheel and probably just as effective)


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PostPosted: Sun Jun 12, 2016 6:44 pm 
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Location: Loveland, CO
I think this is a problem you should ask Bontrager to address assuming the wheel is new and under warranty.


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PostPosted: Sun Jun 12, 2016 8:43 pm 
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Not much stiffer. Maybe 10%. But it's cheap and easy to do so why not? Both Zipp and Shimano use thicker spokes than that on their deep section wheelsets. Use 14ga non butted bladed if they will fit through your hub.


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PostPosted: Sun Jun 12, 2016 11:35 pm 
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Why do you think your wheels aren't stiff enough? Do your brake pads rub when riding off the saddle? Your problem may be with your hub and not your spokes or rim.

http://www.slowtwitch.com/Tech/Debunkin ... _3449.html

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PostPosted: Mon Jun 13, 2016 1:06 am 
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dmulligan wrote:
Why do you think your wheels aren't stiff enough? Do your brake pads rub when riding off the saddle? Your problem may be with your hub and not your spokes or rim.

http://www.slowtwitch.com/Tech/Debunkin ... _3449.html

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Yes my rear brake rubs when riding 'off the saddle' going up hill or while sprinting. I know for a fact that the DT-based rear hub Bontrager uses doesn't have particularly wide flange spacing but I can't change that. Based on the info in the link you provided it looks like heavier gauge spokes will probably help to solve the problem.

Quote:
When you start climbing or sprinting on a carbon wheel, the stiff rim tends to want to stay perfectly straight – relative to itself.

This gets compounded by the fact that most “race” wheels have thin aerodynamic spokes – AND not very many of them. On top of that, in very recent years, we have also seen carbon rims grow in both width and depth – subsequently gaining both lateral and radial stiffness.

What this adds up to is the perfect wheel storm: An astoundingly stiff, deep-section carbon rim – strapped on to a handful of thin aero spokes. The stiff rim can literally overpower the spokes. If your rim rubs your rear brake pads, this is probably why.


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PostPosted: Mon Jun 13, 2016 3:40 am 
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Or rebuild the wheel on a stiffer hub.


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PostPosted: Mon Jun 13, 2016 5:14 am 
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F45 wrote:
Or rebuild the wheel on a stiffer hub.


Could do…

Suggestions for a hub that will build a very stiff wheel, be a reasonable aesthetic match for the front hub, be reliable and not weigh a ton?


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PostPosted: Mon Jun 13, 2016 4:10 pm 
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Tension will be effectively the same on the rim, regardless of the spoke. A thinner spoke can potentially flex momentarily, but that's a very transient phenomenon (like, milliseconds) as the wheel is rotating.

When you are getting wheel rubbing at the brake blocks, you might also check at the chain stays. This kind of rubbing is more about a hub that can't support the wheel build, or about a slightly looseness in the hub bearings that lets the whole hub wobble just enough, or literally about your frame flexing rather than the wheel flexing. You aren't going to get much of a stronger rim than the ones that come on those wheels. And with that rim design, you have enough latent stiffness that you really aren't going to need a higher spoking unless you are quite heavy (you didn't indicate rider weight). You also didn't indicate which frame.


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PostPosted: Tue Jun 14, 2016 12:32 am 
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11.4 wrote:
Tension will be effectively the same on the rim, regardless of the spoke. A thinner spoke can potentially flex momentarily, but that's a very transient phenomenon (like, milliseconds) as the wheel is rotating.

When you are getting wheel rubbing at the brake blocks, you might also check at the chain stays. This kind of rubbing is more about a hub that can't support the wheel build, or about a slightly looseness in the hub bearings that lets the whole hub wobble just enough, or literally about your frame flexing rather than the wheel flexing. You aren't going to get much of a stronger rim than the ones that come on those wheels. And with that rim design, you have enough latent stiffness that you really aren't going to need a higher spoking unless you are quite heavy (you didn't indicate rider weight). You also didn't indicate which frame.


82kg rider weight but I ride with some grace, not a full on masher! Frame is a Colnago C60.

The rear hub bearings have zero lateral play so I know that isn't the problem but with the narrow(ish) flange spacing maybe it is due to the hub. Your feeling is that rebuilding with heavier gauge spokes won't help much? This chart makes a spoke swap look promising...

"The Mavic graph below compares two different spokes to illustrate this – one of 1.8mm diameter, and one of 2.3mm diameter:"

Image

FWIW, I was able to measure my Bontrager/DT rear hub vs the 2015+ Campy Bora rear hub and the Bora's flanges are ~7mm further apart (presumably all on the NDS) compared to the Bontrager. Is this is significant amount in the world of hubs?


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PostPosted: Tue Jun 14, 2016 5:32 am 
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RedRacer wrote:
82kg rider weight but I ride with some grace, not a full on masher! Frame is a Colnago C60.

The rear hub bearings have zero lateral play so I know that isn't the problem but with the narrow(ish) flange spacing maybe it is due to the hub. Your feeling is that rebuilding with heavier gauge spokes won't help much? This chart makes a spoke swap look promising...

"The Mavic graph below compares two different spokes to illustrate this – one of 1.8mm diameter, and one of 2.3mm diameter:"

Image

FWIW, I was able to measure my Bontrager/DT rear hub vs the 2015+ Campy Bora rear hub and the Bora's flanges are ~7mm further apart (presumably all on the NDS) compared to the Bontrager. Is this is significant amount in the world of hubs?


I wouldn't put too much credibility in data such as that from Mavic. Like Zipp and others, their data tend to be pretty biased in favor of what they happen to be doing (their larger diameter spoke systems, for example).

As for your rear hub, having 7 mm more spacing is pretty huge. It doesn't have to be exclusively NDS, but obviously most will be. In fact, on some hubs, the drive side flange won't be as close to the cassette so that 7 mm spread could actually result in an 8 or 9 mm or larger increase in NDS offset. In any case, wheel builders will tell you that there's a huge difference in wheel quality and stability between good hubs and ones with mediocre flange geometry. I've ridden a wide range of wheels and had a few that never felt rigid on hills or in sprints. You most likely have some of that going on here.


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PostPosted: Tue Jun 14, 2016 3:29 pm 
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Location: Loveland, CO
The Campy Boras have more flange offset on the NDS due to the unique spoking pattern (only seven spokes on the NDS). The extra 7mm gives the Boras extra lateral stiffness, hence the superiority of the unique spoking pattern (the same goes for the Shimano carbon wheels). Hubs with regular spoking patterns (say twelve spokes on the NDS) cannot have the extra flange offset on the NDS as the spokes tensions on the NDS will have to be very low which is unacceptable.


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PostPosted: Tue Jun 14, 2016 4:04 pm 
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pdlpsher1 wrote:
The Campy Boras have more flange offset on the NDS due to the unique spoking pattern (only seven spokes on the NDS). The extra 7mm gives the Boras extra lateral stiffness, hence the superiority of the unique spoking pattern (the same goes for the Shimano carbon wheels). Hubs with regular spoking patterns (say twelve spokes on the NDS) cannot have the extra flange offset on the NDS as the spokes tensions on the NDS will have to be very low which is unacceptable.


I don't believe the number of spokes materially changes the tension on any one of them. Ergott, are you reading this thread? Tension is driven by the flange offset and balance between drive and non-drive offsets.

And the point was made above that the Boras would be significantly stiffer simply because of the greater flange spacing. The OP's Bontrager wheels suffer from fairly narrow flange spacing, which is a major contributor to the kind of flexing and brake block rubbing that he sees.


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PostPosted: Tue Jun 14, 2016 4:44 pm 
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Location: Loveland, CO
Of course spoke count on the NDS makes a difference. If you remove half of the spokes on the NDS the tension on each NDS spoke will have to double to maintain the same wheel dish. This is physics 101.

All hubs will suffer from narrow flange spacing unless the hub uses Campy's G3 spoking (or the equivalent Shimano's) which allows for wide flange spacing for superior lateral stiffness. My Shimano rear wheel has only seven spokes on the NDS and wide flange spacing. I don't suffer a stiffness problem, neither do the owners of Campy Boras.


Last edited by pdlpsher1 on Tue Jun 14, 2016 4:44 pm, edited 1 time in total.

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PostPosted: Tue Jun 14, 2016 6:40 pm 
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Flange geometry trumps spoke type, but changing the hub (and as a consequence the spokes) seems a bit extreme. I would rather sell the wheels and buy something else.
Changing spokes only has a lesser impact, but it might be enough for you. Problem is straight pull aero spokes are fairly expensive and I see these rims have internal nipples, which are not the easiest to work with


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