http://www.skf.com/group/products/beari ... index.html
Aerodynamics wise on my Bontrager Aeolus rear hub there is a non rotating portion. If you look at the image below the black cylinder portion on the left next to the dropouts does not rotate with the rest of the hub, so that could be streamlined. However I understand that if we want to make the spoke placement as wide as possible for greater stiffness that would likely not be there.
Non-rotating part; ha, well, I don't know how you intend on making this tube any more aerodynamic than it already is, but I would definitely like to see your thoughts on it.
Regarding the width of the hub; we need to be careful about the distance from the centre of the hub to the spoke positioning on the non-drive side. A wider 'stance' will certainly make for a laterally stiffer wheel, but at the potential cost of spoke tension. With a 2:1 spoking set-up, the non-drive side should be high enough, but this should be carefully considered. A wide non-drive side spoke position could also cause issue with frame clearance (and Garmin cadence metre clearance).
TheDarkInstall wrote:Stage One
I propose the following. Please add, comment whatever you want, so we can get this started.
-24 hole, 16:8 config.
-Straight pull on NDS
-J-Bend or Straight pull on DS
-Standard bearings; 17mm internal diametre.
-Aluminium or Carbon axle. 17mm
-As simple as possible a pre-load system (think more on the side of Tune, than Extralite, for ease of assembly and serviceability)
-Shoulders on the axle to allow for absolutely mental QR tightness
-Triplet lacing greatly restricts rim choices. You need a pretty stiff center drilled rim, or a rim specifically designed for triplet. Triplet has other disadvantages as well.
-Straight pull NDS puts spokes in the way of where you want the bearings to be.
-J Bend is best on the DS for optimizing the offset. This is very important, BTW.
-17mm bearings are ok for the rear, but it might be better to reduce the axle diameter on the NDS side of the hub.
-Make an aluminum axle first. If you get ambitious you can look at a carbon axle later. There is a reason they are not common.
-Axle and end caps are one unit, with a collar on the outside of the NDS to set clearance.
-Shoulders? You mean steel serrations?
I'd advise using higher capacity bearings in the hub body with an axle that captures these bearings, so that the thin freehub bearings won't be subjected to sideloads. I'd probably make the DS hub bearing a 6903 and taper the axle down to 15mm and put a 6902 on the NDS, as close to the dropout as possible. 6803s in the freehub.
Make the hub easy to service without special tools.
What are your goals for this hub?
WMW wrote:-Triplet lacing greatly restricts rim choices. You need a pretty stiff center drilled rim, or a rim specifically designed for triplet. Triplet has other disadvantages as well.
Please list rims where the manufacturer has stated that they are not OK for triplet lacing; I have never experienced a problem with this kind of lacing, on any rim. If anything, the fact that the tensions are more balanced for each spoke means the rim is happier being laced like this, than a 'conventional' system with a larger discrepancy between the DS and NDS spokes. If this is an issue, though, it would be good to look through it and assess.
We have not even started thinking about bearing positions yet, so this point is invalid at the moment. There is the possibility to design a hub with straight pull radial spokes which sit near, or over the bearings, I agree, but we are nowhere near that part of the design stage yet, and it may not even be an issue.WMW wrote:-Straight pull NDS puts spokes in the way of where you want the bearings to be.
Can you explain what you mean by this in detail please; again, we have not started designing the hub yet, so offsets etc., can not be commented on with absolutes.WMW wrote:-J Bend is best on the DS for optimizing the offset. This is very important, BTW.
'OK'? OK in terms of what? In comparison to what, and why, against what criteria? Also, what good will reducing the NDS axle diametre do?WMW wrote:-17mm bearings are ok for the rear, but it might be better to reduce the axle diameter on the NDS side of the hub.
Again, can you explain (or sketch and photo) what you mean by this?WMW wrote:-Axle and end caps are one unit, with a collar on the outside of the NDS to set clearance.
No, I mean shoulders; raised sections in the middle of the axle for the DS and NDS hub shell bearing inner race to sit against, meaning that any lateral load on the inner race will not be able to push the inner race inwards.WMW wrote:-Shoulders? You mean steel serrations?
WMW wrote:I'd advise using higher capacity bearings in the hub body with an axle that captures these bearings, so that the thin freehub bearings won't be subjected to sideloads. I'd probably make the DS hub bearing a 6903 and taper the axle down to 15mm and put a 6902 on the NDS, as close to the dropout as possible. 6803s in the freehub.
I think the first part of this is kind of related to my idea of shoulders on the axle; can you explain more of what you mean by this, as I think we are getting at the same thing! Again though, why do you want to taper down from 17mm to 15mm? Why not just go with a 6803 on the NDS?
About the freebody bearings; I wonder, has anybody got access to, or has indeed carried out, any accurate research about the stresses put through a freebody in a bicycle hub during pedaling? It would be interesting to see what research / engineering theory there is out there, as this will allow us to design a more appropriate bearing system; would the use of angular contact bearings be suitable and better for any part of this, for example?
A tapered axle could make the servicing of the small bearing impossible. If it slips towards the tapered section, good luck pulling it out...
Sent from my iPhone using Tapatalk
Here is a sketch I made for you to all pick apart, and feedback on.
Kind of a mixture of a Tune, Extralite and G-Sport hub, with all the best elements taken from them, and put together with how I am starting to imagine it.
What do you reckon?
Edit; I realised there is a facepalm mistake with this, so prizes* for telling me what it is...
*no actual prizes.
Cantilevers are weak and flexy. It is good to have the main body of the hub supported as close to the dropouts as possible. This is difficult on the DS but not the NDS
Getting the maximum DS spoke offset is important for wheel stiffness and strength. On 11spd hubs with 131mm dropout spacing this is ~ 17.8mm.
The White Industries hub is one example, though I'm not so fond of the collar they use, or the fact that the outer bearings on both sides are subject to sideloads.
The sort of shoulders you are proposing will not prevent preloading. You still need to design the hub for a particular QR pressure and you will need very precise tolerances else you *will* preload the bearings and they will wear out. I think it is best to have a shoulder for the DS hub bearing and an adjustable collar for the NDS (can be set with the wheel in the bike), and the freehub would have a little lateral play. The DS axle cap would need to be removable, and you could thread it to adjust clearance or use thin spacers... but manufacturing tolerances should be adequate to provide a couple tenths of a mm of lateral play.
The 6803 has small bearings and a lower capacity than a 6902. It will wear out sooner. It's good to have a large axle on the DS side because of the long cantilever, but you don't need that on the NDS... especially if you put the bearing close to the dropout.
Making a hub (or anything else) would be a good project, but you need to do your homework first. You seem to be starting pretty much from scratch. I'd advise you to look at discussions on this forum and others regarding wheel and hub design. Also look at Fairwheel's hub review.
Will do as you instruct, mate. Shame to waste valuable internet space on a new project like this, eh.
The Fairwheel review is an excellent source of that.
You need a spacer between the freehub bearings' inner races, and a thin washer the size of the bearing ID between the freehub bearing and hub DS bearing so the freehub bearing's outer race does not contact the hub bearing seal. The part of the hub where the DS bearing fits in looks kind of thin.
Straight pull spokes on the NDS will force the builder to use the lacing pattern you drilled for.
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J -bend spokes are easier to come by so for that reason use those.
A 2:1 lacing pattern is great but tyring to get close to 100% tension balance is going to compromise wheel stiffness as it will mean keeping the NDS flange inboard at 36-37mm. With 2:1 lacing you have the oppertunity to move the NDS flange far out to 40mm+ from centre and still end up with a good tension balance. I mean with a centre of flange to centre of hub spacing DS:NDS of 17mm:40mm you will still end up with a 85% tension balance. Move the NDS flange to 43mm from centre and the tension balance is 79% with a normal medium depth alloy rim. This is still good enough.
Unfortunatley most 2:1 hubs are just redrilled versions of a regualr 24H hub. Whats the point in that, reduced wheel stiffness for higher tension balance a poor trade off in my book. The way I have had my royce hubs made is the dimenions that I think are optimal. rim choice is restrictive so I would not try to make a 2:1 lacing hub and sell it unless you supply a good rim to go with it.
Carbon fibre shell is fine but a carbon axle could be a problem.
the hub I would like would be the following
1) Ti freehub with 6901 bearings
2) main hub shell with 6001 bearing running on a 12mm stainless steel axle
4) 46mm PCD for J-bend spokes maybe more.
5) centre of flange to centre of hub spacing of 17.8mm:38mm.
6) bearing preload adjuster please
In fact a cross between a Miche and Royce hub is the above.
Low tension balance does not matter much as the wheel is stiffer and flexes less. The % tension change with respect to the original tension is what governs fatigue to the actual tension the spokes are under. The above hub will not be made though as everyone wants light at the expense for longer lasting bearings.
Then all we need is a medium depth alloy tubular rim in 18H or 20H front and 24H rear and we are done.
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Just because you can design it doesn't mean you can make it. Just because you can make it doesn't mean you can scale it or make it in such a way that doesn't price the product out of the market.
Center to left 50mm
Right flange about 58mm PCD.
You still get high enough tension on the left for a durable wheel and gain back much or the lost later stiffness of only using 8 spokes.
Traditional flange on the left allows for the combination of wide flange spacing and placing the bearing as close to the dropout as possible. Having the bearings spread far out is the same concept used in the outboard bearings of today's BBs.
I know it's too soon to talk about the following, but still worth keeping in mind. Make sure you perform real benchmark tests with samples before releasing. I believe there is an ISO standard test involving a fatigue run on a drum. I was discussing this with Alchemy. Without this you risk serious failure the won't come up on any CAD drawing. The stresses on a rear hub are incredibly difficult to reproduce for proper FEM.
Best of luck. I'm subscribing to the thread to see this develop.
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