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PostPosted: Sat Jul 12, 2014 10:11 pm 
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I think your kit is an awesome value... but a few comments on what you've stated above.

18mm DS offset (to center) isn't standard for 11spd... rather it is the max if you do everything to squeeze out the last fraction of a mm... including making the dropout at least 131mm. The S11 cassette is 2.85mm wider than the S10, so you need to get half of that in extra space somehow. 16mm-17mm is typical now for 11spd.

A good rear hub design will have the NDS bearing well outboard of the flange. It's better for stiffness and strength to cantilever the larger diameter hubshell than the axle.

The stiffness of all aluminum alloys is essentially the same. A cheaper alloy won't stretch more than a high-strength one. If it has thicker walls the cheap one will stretch less.

Decreasing the NDS flange diameter (assuming the offset is the same) reduces the bracing angle of the NDS spokes... so it makes sense that tension would increase. High NDS tension isn't the goal though, but rather balancing the opposing goals of lateral stiffness and keeping NDS spokes from going slack.

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Posted: Sat Jul 12, 2014 10:11 pm 


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PostPosted: Sun Jul 13, 2014 2:36 am 
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When I said 18mm was pretty much a default I meant, as you point out, that it won't get any better than that for the reasons I listed.

The 11spd freehub body is 1.85mm longer.

My understanding is that with T6 hardening a 6000 series alloy is more elastic than 7075 series alloy with elongation at 8% vs 3-5%.

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PostPosted: Sun Jul 13, 2014 6:57 am 
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Quote:
They measured 11g difference at 30mph for a front wheel... and that was for Lasers, not Race.


Ok, so possibly another .2w compared to the slightly thicker race spokes?

Quote:
If you include the rear wheel which has more spokes, and assuming the rear wheel has some drafting, let's say 20g total. Plus they can't measure aero torque drag in the tunnel which should be at least half the translational. Since we are looking only at spokes, I bet it is more than that... but let's say it's 50%. So 30g total at 30mph (13.41 m/s) at sea level. 30g of drag is .294 N of force. CdA= .294 N/(.5*1.2kg/m^3*13.41^2)= .0027.


According to November Bicycles most of the aerodynamic gains come from the front wheel. The rear wheel sits behind the rider and most of the frame. Unless someone has tested it on a bike with a dummy in the wind tunnel that's just conjecture on your part. BTW, I have no idea what you mean by drafting in this context since drafting typically reduces aerodynamic drag.


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PostPosted: Sun Jul 13, 2014 7:13 am 
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@dunbar I believe Ron meant "shielding" when he said drafting, ie the frame/rider shields the rear wheel a bit

Also, "according to November bicycles" is there information tested? Is it repeatable? Just using a claim like that is no better than a conjecture. I think Ron's biggest point is that the rotation of the wheel also creates aero drag, something which cannot be measured in a wind tunnel.

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PostPosted: Sun Jul 13, 2014 8:44 pm 
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BobDopolina wrote:
The 11spd freehub body is 1.85mm longer.

My understanding is that with T6 hardening a 6000 series alloy is more elastic than 7075 series alloy with elongation at 8% vs 3-5%.


The freehub is 1.85mm longer, but Shimano 10spd cassettes had a 1mm spacer included. At any rate the cassette width for 11spd is 2.85mm greater.

You are referencing a test that measures plastic deformation (beyond yield) before a material completely breaks in two. When spoke tension stretches the bearing bore, the material will definitely be stressed at less than yield and the deformation will be proportional to the modulus of elasticity... which is approximately the same for all aluminum alloys.

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PostPosted: Sun Jul 13, 2014 9:06 pm 
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dunbar42 wrote:
Ok, so possibly another .2w compared to the slightly thicker race spokes?

According to November Bicycles most of the aerodynamic gains come from the front wheel. The rear wheel sits behind the rider and most of the frame. Unless someone has tested it on a bike with a dummy in the wind tunnel that's just conjecture on your part. BTW, I have no idea what you mean by drafting in this context since drafting typically reduces aerodynamic drag.


A race spoke is 1.8mm in the center vs 1.5mm for Laser... so I'd expect ~20% more drag... but this is absolute, not the amount greater than CX-Rays.

But the calculation I did was for Lasers anyway. November only tested a front wheel which is why I added a rear one.

AFAIK they are the only ones to publish data on a direct comparison where only the type of spoke was changed. I've been collecting Tour's wind tunnel data for many years, and there appears to be an obvious gain from aero spokes when comparing similar (though never identical) wheels. Most of their wheels have aero spokes except for the higher spoke count "customs", so there isn't a large data set.

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PostPosted: Sun Jul 13, 2014 9:15 pm 
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BobDopolina wrote:
The correct drawing has already been posted.
but it's not on your web site.... in fact I don't know where it is on the web, only that it was posted here.
BobDopolina wrote:
The specs listed on our website are those provided by the manufacturer and in the seven years I've been working with these hubs have yielded correct spoke lengths when used in any calculations.


There is a notable difference between the number listed on your web page and the real number from the diagram. As you know it's not about spoke lengths, it's about wheel lateral stiffness. It's an important issue for some people building wheels.

Right now your web page shows a number which is not even possible. Are you suggesting that customers should see that, know that it's not possible, find the correct drawing someplace and use that?


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PostPosted: Mon Jul 14, 2014 12:46 am 
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We don't post drawings on our site for the reason demonstrated above; people get it wrong. Instead we list the numbers for you.

Regarding the drawing posted I believe it was posted by me BEFORE the 11spd version of the hub was released. It was a preliminary drawing only and the point was to show proposed changes. The actual hub dimensions were adjusted from this drawing, including flange widths and, more specifically, they went to 131OLD. This is important.

Looking at the drawing: (50.6+1.6+1.6)/2=26.9. Subtract the listed offset of 10 and you get 16.9. Novatec then went to 131OLD adding it to the DS giving 17.9. We list it at 18.

In seven years of building, riding and selling these hubs we have never had anyone complain about a wheel that wasn't laterally stiff. Not once. The flange spacing is good and the bearing stance even better.

This is a mature hub with a proven track record.

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PostPosted: Mon Jul 14, 2014 3:04 am 
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I am not questioning the quality of the hub, I am questioning the quality of your information about it.

Adding a spacer to the DS end of the axle would move the hub flanges to the NDS relative to the center line of the wheel, by half the thickness of the spacers (because the axle is held between dropouts which are spaced equally). Imagine adding 6 inches to the DS end of the axle and placing the hub in a frame with very widely spaced dropouts. The hub flanges are now far over to the NDS. If that's what they did it would reduce the DS flange spacing, not increase it. Perhaps you meant something else.

In any case even if it is 18mm your web site says 19mm.

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PostPosted: Mon Jul 14, 2014 4:23 am 
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The website is wrong. This will be corrected today. The 19mm should be from the Campagnolo freehub on the 10spd hubs.

I reread my post and it wasn't clear. The numbers we give are the ones that come from the manufacturer and are what we post on our site. I assume they are taken from the working drawings and therefore are correct.

EDIT: This is from the 2103 catalog and differs from my drawings dated just prior to this:

Based on my drawings FTF is measured outside to outside so I will assume the same here.
Flange thickness I also have at 3.2mm and will assume this as well.
My drawing has the offset at 9mm but the catalog lists 9.5mm so:

57mm-3.2mm/2=26.9mm Subtract the offset and we have 17.4mm.
57mm-3.2mm/2=26.9 Add the offset and we have 36.4mm

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Last edited by BobDopolina on Mon Jul 14, 2014 8:28 am, edited 1 time in total.

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PostPosted: Mon Jul 14, 2014 8:17 am 
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WMW wrote:
The freehub is 1.85mm longer, but Shimano 10spd cassettes had a 1mm spacer included. At any rate the cassette width for 11spd is 2.85mm greater.


Which doesn't matter for the purposes of this conversation. What does matter is the additional freehub length.

WMW wrote:
You are referencing a test that measures plastic deformation (beyond yield) before a material completely breaks in two. When spoke tension stretches the bearing bore, the material will definitely be stressed at less than yield and the deformation will be proportional to the modulus of elasticity... which is approximately the same for all aluminum alloys.


Modulus of elasticity for 6061 T6: 68.9 GPa
Modulus of elasticity for 7075 T6: 71.7 GPa

So about 4%.

How much deformation will occur with radial lacing at full tension? I honestly don't know. How much is needed to push the bore beyond tolerance and cause the problems I've seen first hand in the OE? Again, I don't have numbers for this but if the bore is already pushing the outer limit of tolerance it doesn't take much.

The problem we have seen (at the assembly factory) disappeared once spoke tension was reduced about 10%~15% so I would conclude that the potential issue is real and materials related. The factory we were working with (not Novatec) concluded the same.

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PostPosted: Mon Jul 14, 2014 8:02 pm 
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Actually it is the freehub length that immaterial if we are talking about DS offset. The cassette width is what matters... or more precisely chain clearance in the small cog and derailleur clearance in the large one.

The spokes can also put leverage on the hub flange (particularly if it is large) and distort the bearing bore. Did the bearings get loose, or did they bind? Why do you think it was material related rather than design related? Several high end hubs use 6061-T6. It's the best hub alloy IMO because of its corrosion resistance and lower sensitivity to notching.

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PostPosted: Mon Jul 14, 2014 8:30 pm 
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istigatrice wrote:
Also, "according to November bicycles" is there information tested? Is it repeatable? Just using a claim like that is no better than a conjecture. I think Ron's biggest point is that the rotation of the wheel also creates aero drag, something which cannot be measured in a wind tunnel.


November Bicycles tested their wheels in the wind tunnel with the wheel rotating. I'd say that's a heck of a lot more scientific than "I ran some calculations" or "here are some random numbers I came up with off the top of my head."

http://www.novemberbicycles.com/blog/20 ... -rays.html


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PostPosted: Tue Jul 15, 2014 6:10 am 
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WMW wrote:
Actually it is the freehub length that immaterial if we are talking about DS offset. The cassette width is what matters... or more precisely chain clearance in the small cog and derailleur clearance in the large one.


Actually, both are set in the factory manuals by the component makers as is, more importantly, the chainline. There is no wiggle room there for the hub makers.

WMW wrote:
The spokes can also put leverage on the hub flange (particularly if it is large) and distort the bearing bore. Did the bearings get loose, or did they bind? Why do you think it was material related rather than design related? Several high end hubs use 6061-T6. It's the best hub alloy IMO because of its corrosion resistance and lower sensitivity to notching.


After we halted assembly and contacted the hub vendor we discovered that they had made a running change as they felt, and as you point out, that 6000 series alloys were easier to work with (and cheaper. Bastids). The customer had specified 7075 and when the hubs were produced to this spec the problem didn't occur. It also went away once the hub vendor switched back so, in this instance, I feel pretty confident in saying it was a materials issue.

Having said that, I have also seen this problem because of bearing bore tolerances and because of flange placement and due to the fact that the hub shell vendor was unaware of a slight mod that can be made to address this. We do this with hubs we make in the OE to address this exact concern (sorry, I'm not going to say what it is) and this extra machining step seems to work.

Since we have gone off on this tangent why do you think some hub vendors say that you can not radially lace their hubs? What potential problems are they trying to avoid?

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PostPosted: Tue Jul 15, 2014 7:56 am 
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For those interested here's an update on my experience with the kit:

I've just recieved my parcel from BDOP, after ordering it was shipped on the 10/07/14. Parts are all well packed and nothing was damaged in transit.

The front hub weighs 79g and rear 241g - almost bang on.
Rims were 506g and 496g - fairwheel lists them as 498g so they are also bang on.
The rim tape they supply is 21g, pretty average in terms of cloth tape.

Sadly, my package is missing the quick releases. I flicked an email to BDOP and they replied in a very professional and polite manner - would rate!

I've deicded to source alloy nipples and Pillar X-TRA 1422 spokes from elsewhere, with this config the kit weighs 1568g. For those interested this saves 56g from the standard brass nipples and Race spokes. It doesn't save alot of weight but should also be a touch more aero and easier to build. The lengths required are 279mm for the front and rear NDS and 283 for the rear DS (rear is 2x both sides and front is radial).

Now to get building... As a side note, do people rate linseed oil as a good spoke lube?

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Posted: Tue Jul 15, 2014 7:56 am 


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