DT 240s and spoke bracing angles

JonEdwards

I'm looking at new wheels for a new "best bike" build, most likely handbuilts. Looking at 24 hole SL23 rims F&R, +CX rays. I'm 64kg, live on the edge of the Peaks, like climbing, love descending. Don't race, just ride (solo) for the hell of it. Hour blasts to all dayers. Might consider some of the nastier sportives next year.

Hubs are when I run into issues. Default choice would be DT 240s, as I've run them on MTBs and they Just Work (tm). Except I keep running into reports (mostly on here) of the poor bracing angles due to the flange spacing/dia. Now I've sketched this up in Autocad (assuming radial lacing, which obviously will be incorrect), and there really does seem to be absolutely chuff all in it. Compared to a varitey of other hubs, the front is wider spaced, rear drive side is nigh on identical, rear NDS, the DT is 1.7-2mm narrower. Does that really make all that much difference???

Am I making too much of this? Being a lightweight, is it even slightly an issue? What hubs would people recommend outside of DT? I'm pretty weight weenie, but not a fan of fragile stuff either (hence liking DT). Not afraid of spending cash when necessary, but don't have to.

(for sake of reference, I have the DT hub dims as Front flange PCD 39mm, C->F 37.4mm. Rear flanges PCD 45mm, C->DS 17mm, C->NDS 33.2mm)

ugo.santalucia

It's empirical. I started building wheel as I kept braking on a set of DT 240 laced to shallow rims with 28 DT revs spokes...

All in all, the Pacenti is a much stiffer and marginally deeper rim than the DT 415 I had, but it's still not the best choice of hub. I think you will be OK, but why insisting with the DT 240 with the same money buys you Dura Ace or else with a better geometry?

cycleclinic

It is the non drive side angle that the problem. Hubs with a flange to centre distance of 33mm on the NDS compared to 36mm for DA9000 hubs and Campagnolo record, 38mm for Miche Primato and 35mm for Royce just do not impart enough lateral stiffness to the wheel.

The difference is not huge but it can be felt. Given the more flex you get in a wheel the faster the spokes fatigue it is actually quite important. DT Swiss make the hubs this way go give high NDS rear spoke tensions but higher tensions do not lead to a stiffer wheel just a wheel that can flex more (and it will) before the NDS rear spokes go slack and the wheel falls over (well not literally and the brake pads stop it).

DT swiss disc brake hubs are much better as the the spoke count is often higher rims can be stiffer, and thicker spokes are used plus the DS flange to centre distance is 19.5mm which helps too.

24H Pacenti SL23 with DT comp spokes and DT Swiss 240 hub would be stiff enough to last. Use a thinner spoke and someone of your weight might get away with it but why comprimise?

rrsodl

thecycleclinic wrote:

It is the non drive side angle that the problem. Hubs with a flange to centre distance of 33mm on the NDS compared to 36mm for DA9000 hubs and Campagnolo record, 38mm for Miche Primato and 35mm for Royce just do not impart enough lateral stiffness to the wheel.

The difference is not huge but it can be felt. Given the more flex you get in a wheel the faster the spokes fatigue it is actually quite important. DT Swiss make the hubs this way go give high NDS rear spoke tensions but higher tensions do not lead to a stiffer wheel just a wheel that can flex more (and it will) before the NDS rear spokes go slack and the wheel falls over (well not literally and the brake pads stop it).

DT swiss disc brake hubs are much better as the the spoke count is often higher rims can be stiffer, and thicker spokes are used plus the DS flange to centre distance is 19.5mm which helps too.

24H Pacenti SL23 with DT comp spokes and DT Swiss 240 hub would be stiff enough to last. Use a thinner spoke and someone of your weight might get away with it but why comprimise?

As it happens, I've been reading the Bicycle Wheel by Jobst Bradt and you both don't seem to quite share the same view.....

I'll quote a few passages to state JB position on wheel strength and stiffness which I find interesting.

"Strength is a measure of the greatest load the wheel can carry before it collapses."

"Therefore, the tighter its spokes are (up to a point), the greater a wheel's load capacity. Wheels have both radial and lateral strength. Although both improve with increasing spoke tension, lateral strength is mostly dependent on how far apart the hub flanges are spaced. If the spokes are sufficiently tight that they do not become slack from vertical loads, then both lateral and torsional loads are no concern because they are relatively small and usually do not occur in conjunction with extreme vertical loads."

"Stiff wheels are often mentioned with approval. However, it should be noted that a bicycle wheel is so rigid that its elasticity is not discernible because the tires, handlebar stem, frame, and saddle have a much greater combined elasticity. Therefore the differences among well constructed wheels are imperceptible to a rider."

"Stiffness is a measure of how hard it is to deflect the wheel or, more precisely, the ratio of load to displacement. Stiffness is not strength."

"Wheel strength, and not stiffness, is the important consideration. If the wheel is strong enough for its intended use, then it is more than adequately stiff."

While it is widely accepted that the bracing angle affects the lateral stiffness, JB is of the view that tighter spokes improve radial and lateral strength and that would be a more important consideration.

ugo.santalucia

Stiffness and strength can come in the same package, as well as they cannot. The market is littered with 20 spokes rear wheels which are stiff enough by design but not very strong in terms of the load they can effectively carry for a given mileage.

Yes, in a way you can say that your wheel can carry a load proportional to the total load applied to your rim by the spokes, but lateral stiffness is mainly down to geometry and to an extent spoke choice.

In essence I don't think JB and TCC are saying fundamentally different things, they are just taking a different angle on the same subject

rrsodl

ugo.santalucia wrote:

Stiffness and strength can come in the same package, as well as they cannot. The market is littered with 20 spokes rear wheels which are stiff enough by design but not very strong in terms of the load they can effectively carry for a given mileage.

Yes, in a way you can say that your wheel can carry a load proportional to the total load applied to your rim by the spokes, but lateral stiffness is mainly down to geometry and to an extent spoke choice.

In essence I don't think JB and TCC are saying fundamentally different things, they are just taking a different angle on the same subject

Stiffness and strength can be in the same package together indeed. They are not mutually exclusive but desirable.



I also agree that they both have a slightly diiferent angle on the highlighted text. I guess if JB didn't have an option of a hub with wide flanges then he would build for strength quite happily.

On the other hand, If you were to check Harry Rowland site, you'll see that he will not build certain rims and hubs combination that don't offer good strengh and stiffness.

Like many things, one has to look at the rider weight and riding style to decide what components are best suited.

JonEdwards

OK, this is starting to get a bit more of a discussion. The trade off between flange spacing and tension balance is interesting.

I'm not absolutely sold on DTs. On the other hand, I'm rather less sold on DA 9000 or Campag. Both are relatively heavy (yes I know its only 35-40g, but I did say I was a weight weenie), and more importantly, both will need a lot more routine maintenance to keep running sweet - its the downside of cup'n'cone, you *have* to look after them if they're to last. I've beaten the snot out of the 240s on my Enduro MTB, year in, year out, all weather, and they just don't need touching, Proper fit and forget stuff.

Assuming equal bias between weight, maintenance and stiffness, and assuming the DTs will produce a "stiff enough" wheel, DTs still score 2 points (weight, maint) to Shimanos 1 (geo).

I'll also leave this quote here:-

FWB Opinion: In reviews of the past the 240 has been a hub that didn’t stand out. It hit mid-field in just about every category making it a fairly well balanced hub. However with the new 11 speed dimensions my opinion of this hub has changed making it one of my favorite hubs. Bracing angle is now very respectable and tension balance is one of the best in the review. The DT uses a star ratchet over the traditional pawl system which gives it a simple and reliable drive system. Over the years the 240 has shown itself to be ultra reliable and the fact that parts and service can be had at virtually any shop in the world means the DT240 has become one of my favorite go-to hubs for a daily rider

From http://fairwheelbikes.com/c/forums/topic/2014-road-hub-review/

So if I'm after a light, reliable, cartridge bearing hub, what else do I look at?
American Classic - don't do the 105 f/hub in 24 hole, only the Micro58, and that looks a bit fragile.
Hope - porky, I've had reliability issues in the past. Had drag issues with MTB hubs (no experience of the mono RS though in that respect). Would stick them on a commuter/winter bike without a second thought though.
King. £££££. My other half's pair have been a right PITA
White Industries. Look pretty good, bar a bit tubby.
Carbon Ti - on paper look very nice - light, big flanges (but I can't find any proper dimensions). Not sure of availability.
Novatec. Too many options!!

cycleclinic

I don't use the word strength when talking about wheels normally because I think it is a mis use of the word. Strength means the load something can take before failure. This is not desirable in a wheel what is important is how stiff it is. The higher the lateral stiffness the less flex you get and therefore the less unloading of spokes (there are three type of stiffness in a wheel as well radial, lateral and torsional). Take a mavic op rim DT swiss hub in 32 drilling and sapim race spokes. It would be an appaling wheel in terms of lateral stiffness and will mostly likely break spokes before it should. Replace the rim with a Archetype and it will be a stiff wheel again and last longer. Use a cheaper Dura ace hub and it will be stiffer still and the spokes will last even longer. Neither wheel should ever be loaded to the point of collapse or even close to that, so how "strong" it is is irrelevent.

If you want long spoke life high bracing angle (7 speed hub with 130mm OLD (45mm PCD with 37mm/22mm flange to centre dimensions) in 32h or 36H with a wide medium depth rim and use a sapim race spoke. I doubt spoke breakage would ever be an issue with such a wheel but it would not be a racing wheel either. So if you want a really stiff rear wheel go back to 7 speed or better ride fixed. The other option is a 2:1 lacing pattern but a custom hub will be required with 50mm NDS flange centre distance and 17.8mm DS flange to centre as that is the largest it can be for 11 speed shimano. Royce will do one for a high price. I have one as well its brilliant and tension balance is excellent and even though the wheel only has 24 spokes it i the stiffest thing I have ever built.

for me Campagnolo record and Shimano Dura Ace as the best hubs about apart from Royce which are more expensive but have 6001 cartridge bearings, ti free hub and are even heavier. To me the weight of the hub is irrelevent. stop being a hub weight weenie and get some proper hubs. All the light weight hubs have reliability issues, not one I would ride on perosnally except the novatec A291/F482 SB-SL and the only reason they are cheap and the spares are cheap too. I would not pay ££££££££££ for a weight weenie hub that eats bearings and who's spares cost a fortune and worse requires expensive tooling to maintain.

ugo.santalucia

JonEdwards wrote:

So if I'm after a light, reliable, cartridge bearing hub, what else do I look at?
American Classic - don't do the 105 f/hub in 24 hole, only the Micro58, and that looks a bit fragile.
Hope - porky, I've had reliability issues in the past. Had drag issues with MTB hubs (no experience of the mono RS though in that respect). Would stick them on a commuter/winter bike without a second thought though.
King. £££££. My other half's pair have been a right PITA
White Industries. Look pretty good, bar a bit tubby.
Carbon Ti - on paper look very nice - light, big flanges (but I can't find any proper dimensions). Not sure of availability.
Novatec. Too many options!!

PMP... the silver ones have a stupendous opalescent finish and very high quality at a good price

letap73

In terms of rotation, an equivalent mass close to the axis of rotation requires less torque than the same amount of mass at the outer edge of the wheel for a given time period of rotation. This means in terms of spinning up a wheel you are unlikely to notice the greater mass of a hub (especially if there is 50-100 grams in it). At the same time I am not advocating the use of a lightweight rim unless of course it can be built into a durable and safe wheel!

apreading

There seems to be alot of debate about this, and plenty of bike builders who still sell, and indeed recommend, the 240 hubs. Plus DT have a deliberate reason for what they do, so they must have some experienced techs who genuinely believe in the choice. Had for many of us to work out who is right but if the hubs are so obviously bad then I am sure DT would change them - they must have heard the negative comments...

Another discussion here:

http://forums.roadbikereview.com/wheels ... 26286.html

cycleclinic

They do what they do to improve tension blance because some wheelbuilders do not control tensions very well. If such a wheel builder uses a miche hub for example the wheel will fail as some NDS rear spokes will have little tension while other have a bit more than they should. This is a problem with any hub with low tension balance but if you have good control of tensions then it no longer is a problem particulaly if you use an off set rim like the DT Swiss RR440 or Ryde Pulse Sprint.

Dt swiss hubs do have good quality bearings but so do other hubs and they also have an excelent freehub mechanism but so do Royce, White Industries and Shimano hubs. So all in all the upside do not outweigh the down sides.

Also just because DT swiss make the hub this way does not mean they know what they are doing, otherwise every product on the market would work brilliantly which is not the case is it. If sales suffer DT Swiss would revise the design if sales are strong they won't.

apreading

So you are saying that DT design the hubs like this to compensate for the fact that over half the wheel builders out there cannot build a wheel properly? (almost all seem to offer the 240 hubs and be willing to use them and I can see as many or more praising the hub on various web forums as I can find citing problems with the flange width - after a google etc)

And that if DT's design had any merit then everyone else would do it too, like the universally priased and unique freehub that they use?

I am not saying you are wrong but the industry does seem a little divided over this issue and lots of builders cite having built lots of wheels on these hubs that they are happy with.

Just the question mark would give me pause for thought, especially if looking at a low spoke count, but then my wheels use disc hubs and higher spoke counts. If I were buying hand built tomorrow though, I would have put the DT350 disc hubs right at the top of my list (until now)...

ugo.santalucia

apreading wrote:

There seems to be alot of debate about this, and plenty of bike builders who still sell, and indeed recommend, the 240 hubs. Plus DT have a deliberate reason for what they do, so they must have some experienced techs who genuinely believe in the choice.

1) There is a good mark-up on a 400 quid pair of hubs... I can see the appeal in recommending them...

2) DT swiss makes good components and awful wheels... their doomed 1450 Mon Chasseral were the very reason I began the wheel building journey 7 years ago. More recently they have come out with gems like the "Tricon" system that make no sense at all except to them.
DT Swiss is about 20 years old, it's no Campagnolo... they started by making spokes and that's what they do well... forging, rolling, drawing, bending stainless steel. Then they developed the Hugi ratchet system, which is nice and still in use in pretty much all their range of hubs. Then they ventured in the world of rims, where they never really made a mark, as none of their rims excels in any way, shape or form and finally they offered assembled wheels, which are pretty much all crap... so that's my take on DT Swiss...

JonEdwards

So you are saying that DT design the hubs like this to compensate for the fact that over half the wheel builders out there cannot build a wheel properly? (almost all seem to offer the 240 hubs and be willing to use them and I can see as many or more praising the hub on various web forums as I can find citing problems with the flange width - after a google etc)

This is exactly what sparked my original post.

I did speak to Jon Webb at JRA (who's my LWB) about this, and his opinion was that it wasn't much of an issue, although I think he used the word "shouldn't", not "won't", which is not as definitive an answer as it might be...

rrsodl

thecycleclinic wrote:

I don't use the word strength when talking about wheels normally because I think it is a mis use of the word. Strength means the load something can take before failure. This is not desirable in a wheel what is important is how stiff it is. The higher the lateral stiffness the less flex you get and therefore the less unloading of spokes (there are three type of stiffness in a wheel as well radial, lateral and torsional). Take a mavic op rim DT swiss hub in 32 drilling and sapim race spokes. It would be an appaling wheel in terms of lateral stiffness and will mostly likely break spokes before it should. Replace the rim with a Archetype and it will be a stiff wheel again and last longer. Use a cheaper Dura ace hub and it will be stiffer still and the spokes will last even longer. Neither wheel should ever be loaded to the point of collapse or even close to that, so how "strong" it is is irrelevent.

If you want long spoke life high bracing angle (7 speed hub with 130mm OLD (45mm PCD with 37mm/22mm flange to centre dimensions) in 32h or 36H with a wide medium depth rim and use a sapim race spoke. I doubt spoke breakage would ever be an issue with such a wheel but it would not be a racing wheel either. So if you want a really stiff rear wheel go back to 7 speed or better ride fixed. The other option is a 2:1 lacing pattern but a custom hub will be required with 50mm NDS flange centre distance and 17.8mm DS flange to centre as that is the largest it can be for 11 speed shimano. Royce will do one for a high price. I have one as well its brilliant and tension balance is excellent and even though the wheel only has 24 spokes it i the stiffest thing I have ever built.

for me Campagnolo record and Shimano Dura Ace as the best hubs about apart from Royce which are more expensive but have 6001 cartridge bearings, ti free hub and are even heavier. To me the weight of the hub is irrelevent. stop being a hub weight weenie and get some proper hubs. All the light weight hubs have reliability issues, not one I would ride on perosnally except the novatec A291/F482 SB-SL and the only reason they are cheap and the spares are cheap too. I would not pay ££££££££££ for a weight weenie hub that eats bearings and who's spares cost a fortune and worse requires expensive tooling to maintain.

It seems the angle TCC and JB are coming from and ugo was referring to, is wider that I first though but it's all great stuff, very interesting to read different opinions from experienced people on such interesting subject.

I'll jump to the deep end with the following quote from JB:
"Although it is worth analyzing, stiffness is not an important consideration in
wheel design. Components and spoke patterns should be selected for strength
and durability. A wheel that is strong enough to withstand the loads of its
intended use is also stiff enough. Stiffness is often put forth as an excuse for
peculiar designs. "It makes the wheel stiffer," is often claimed in defense of an
unconventional design. However, some of the world's strongest cyclists have
ridden the kilometer time trial on 24-spoke small-flange wheels with light-
weight rims. Although this event requires precise control and enormous starting
torque that exceeds nearly all stiffness and strength demands of other cycling,
these racing wheels are adequately designed for their specific use. They lack the
long-term durability of road wheels, but they are stiff enough."

"spokes break from fatigue, not excessive force, and they break
when they pass the bottom of the wheel, at a point where they leave the load-
affected zone and return to normal tension. So it is not the bump in the road,
but leaving the bump that breaks the spoke."

"Spoke fatigue is caused by the combination of static load, the carried load, the
distance traveled, and the number of spokes that share the work. The heavier the
load, the more rapidly spokes fatigue."

"The terms `stiffness' and `rigidity' are often used when people talk about
bicycles. Unless these terms are defined, they are just as vague as the even more
popular catchall term `responsiveness.' These technical-sounding words can be
misleading. Stiffness alone is not the ultimate measure of a good wheel, but
rather the balance of stiffness and strength that enables it to carry loads and
withstand shocks."

BTW, I'm awaiting delivery of some DA7900 hubs and I'm just looking at their dimensions I find that the left flange offset is only 34mm :shock: Every review I read say they are great hubs though

cycleclinic

I use stiffness in the way it is meant to be. Stiffer wheels flex less which mean spokes fatigue at a slower rate so it is very important indeed. The higher the spoke count the stiffer the wheel the lower the spoke count the less stiff it is in the two important ways, lateral and torsional. radial stiffness is mostly governed by the rim and spoke count has little impact. Modern rims are so stiff though that lower spoke counts can still high mileages. Josh brandt wrote his book a long time agao rim design has moved on allowing new possibilities. Also rim wear in the U.K limits the life of a wheel such that mega mileages (20,000+) are not that common.

In fact stiffness is a very precise term. It is load divided by extension or length change. It is the length change on a spoke that causes fatigue. Not vague at all if used properly. Lateral stiffness is load/lateral deflection under that load in N/mm. I think Strength is the vague term in wheels. I get asked alot is the wheel strong one asked is it sexy but I was not sure how to answer that), what does that mean exactly are you going to throw it at a wall repeatidly ump up and down on it? Josh brandt is describing fatigue mostly which is linked to the stiffness of the wheel as I have tried to expain not its "strength" that's the mistake in the article you quoted.

Josh brandt may know a thing or to but just becuase he wrote it does not mean it is gospel truth. DA hubs have a centre flange to centre measurements of 36mm/17mm. Shimano measure from the inside of the flange, I measure from the middle.

rrsodl

thecycleclinic wrote:

I use stiffness in the way it is meant to be. Stiffer wheels flex less which mean spokes fatigue at a slower rate so it is very important indeed. The higher the spoke count the stiffer the wheel the lower the spoke count the less stiff it is in the two important ways, lateral and torsional. radial stiffness is mostly governed by the rim and spoke count has little impact. Modern rims are so stiff though that lower spoke counts can still high mileages. Josh brandt wrote his book a long time agao rim design has moved on allowing new possibilities. Also rim wear in the U.K limits the life of a wheel such that mega mileages (20,000+) are not that common.

In fact stiffness is a very precise term. It is load divided by extension or length change. It is the length change on a spoke that causes fatigue. No vague at all if used properly. Lateral stiffness is load/lateral deflection under that load in N/mm. I think Strength is the vague term in wheels. I get asked is it strong. what does that mean exactly are you going to throw it at a wall repeatidly? Josh brandt is describing fatigue mostly which is linked to the stiffness of the wheel as I have tried to expain not its "strength" that's the mistake in the article you quoted.

Josh brandt may know a thing or to but just becuase he wrote it does not mean it is gospel truth. I also happen to know a thing or to. DA hubs have a centre flange to centre measurements of 36mm/17mm. Shimano measure from the inside of the flange, I measure from the middle.

Yes, very true that JB wrote his book quite a while ego, 1993 I think, and things have moved on since then but the laws of physics don't change. He has an interesting background in engineering and he used to work for Porshe hence his book is rather heavy on the physics side of wheel building. Having read the book on wheel building by Roger Musson and having built a few wheels I wanted to read areas of wheel building that RM doesn't talk about in his book. JB's book seems to be a good read but I also find your posts and Ugo's equally interesting.

The dimensions of the hubs are what I found on the net, possibly wrong, so thanks for the info.

src1

thecycleclinic wrote:

They do what they do to improve tension blance because some wheelbuilders do not control tensions very well.

Hi, could you expand on what you mean by this a bit please? Do you mean some wheel builders make a poor choice of components that lead to low tension on the NDS, or something else?

Once components are chosen, AFAIK you can't really influence NDS tension with special wheel building skills. It'll be determined by how much tension you can put on the DS, the hub dimensions and any offset in the rims - or am I missing something?

cycleclinic

Some wheelbuilder may not get even spoke tension. so if say the DT swiss hub had the geometry of a miche hub well I have seen the result of a poor build with these it = broken spokes as all it take is one low tension spoke and that the one that fails first. So moving the NDS flange inboard raise NDS tensions and therefore mean if the wheel builder has un even NDS rear spoke tension it is not that bad for wheel. I have already said this so yes you are missing osmething.

Compenent choice needs to reflect the geomety of the hub so the DT hub need very stiff rims. Hense I would only ever use them with deep section carbon rims but now Madison are realising 18h front DA9000 hub the point in the DT Swiss hubs has kind of evaporated.

src1

Can't see where you've said that earlier in this thread. Perhaps you meant in one of your other posts? Anyway, thanks for explaining what you meant, it was a genuine question.

All the best,
Rob.