Anyone heard of the tour du france? big race in erm, france... 200 pro riders, 2500kms 105 years, 3 weeks in the saddle...

 

16 carbon spokes in the front wheel... 20 in the back! www.Mavic.com - Products - R-Sys Premium

That's nice, how many ebikes have carbon spokes?

Firstly, freestyle BMX bikes take a beating in a totally different way. you dont see people on road bikes doing tail whips or back flips do you...

 

secondly, reducing the weight on an E bike makes perfect sence. Lighter weight = more efficent, increased range and better handling.

 

But If you'd rather ride a 30kg plus tank with 36 spokes then...good on you I suppose.

Someone who adds over 500g to each wheel by fitting Marathon Plus tyres isnt going to worry about the much smaller weight of a dozen spokes, I think most ebike users would go for practicality first especially if the roads are as bad as we are told.

What is the weight of 12 standard ebike spokes?

Firstly, freestyle BMX bikes take a beating in a totally different way.

 

Sorry, no they don't. Running across a pothole impacts the spokes in no different a way. An impact shock is an impact shock.

 

secondly, reducing the weight on an E bike makes perfect sence. Lighter weight = more efficent, increased range and better handling.

 

You clearly haven't thought this through. On the Pro Connect for 36 spokes, the extra spokes and nipples less the weight of the extra rim holes is some 80 grams per wheel, that's eight one-hundredths of a kilo. It would increase the nominal weight of the bike from 20.8 kilos to 20.9 kilos and would have absolutely no detectable effect on efficiency, range or handling.

 

A rider eating an energy boosting small banana before setting off adds twice that extra, a small energy boosting drink adds three times the extra weight of those spokes, so the extra weight is inconsequential.

 

But If you'd rather ride a 30kg plus tank with 36 spokes then...good on you I suppose.

 

As you see from the above, sufficient spokes for reliability don't make a 30kg tank. Of course I agree that as light as possible is desirable on a bike, but such a minute gain as in this case is only acceptable if there is no other loss.

 

The 36 spoke Agattu introduced last year has sold in large numbers with no spoke troubles, while their 24 spoke Pro Connect appearing recently in late spring has had at least two wheels with trouble already. A very small incidence, but ask those owners if they'd rather have a spoke problem or an extra eight one-hundredths of a kilo on the wheel and I know what the answer would be.

.

depends on spoke gauge, wheel and hub type. But put simply if its a 700c wheel running 36 spokes chances are its pretty low end, heavy and more likely to be pone to things like rusting spoke nipples and surface rust on both the spokes and the rim increasing the chance of spoke failure.

What has the number of spokes got to do with rusting?

Thanks for the update Mark, and I appreciate the difference with shorter spoke tensions, used myself in my 20" bike's wheel rebuild with some very high tensions.

 

But I still have a preference for over 30 spokes on e-bike and other utility bike road wheels, since they are more forgiving of poor road conditions and wheel build variations. As I've shown, the weight and dynamics gain of fewer is too small to be of consequence. Fine on a top race bike for competition and built to exacting standards, but even the very light Pro Connect weighs well over twice those.

.

Firstly, freestyle BMX bikes take a beating in a totally different way. you dont see people on road bikes doing tail whips or back flips do you...

 

secondly, reducing the weight on an E bike makes perfect sence. Lighter weight = more efficent, increased range and better handling.

 

But If you'd rather ride a 30kg plus tank with 36 spokes then...good on you I suppose.

 

It's interesting to note that the Nexus 8 gear hub has been developed steadily by Shimano over the past few years, and gaining in popularity as its strength and reliability has improved.

 

From what I can see, the SG-8R25 hub and the WH-8R25 complete wheel were launched at about the same time a couple of years ago. This "redband" premium version of the hub had various upgrades incorporating needle roller bearings and better sealing against the elements.

 

The latest offering from the redband developments is the SG-8R36 hub, and the new range of Alfine hubs, designed with the same gear internals plus the facility for disk brakes.

 

There is growing interest in using these hubs on tougher terrain here.

 

 

Interestingly, the hubs have only been available as 32 or 36 spoke versions. Only the Shimano wheel as used on the ProConnect has used a 24 spoke version, and the 24 spoke wheel is not very widely available (not imported to the UK).

 

James

30+

 

Hi Flecc

 

Seems you are looking at this from an old fashioned point of view.

Thing have really changed since needing 30+ spokes.

 

thx

 

Bob

What has the number of spokes got to do with rusting?

 

...didn't I just explain why?

I think you just told me that a 36 spoke wheel is cheap and nasty and will use mild steel spokes whilst a 24 spoke wheel is the premium that most people have and has stainless steel spokes.

Whether stainless is better than mild is a different discussion and has nothing at all to do with the number of spokes on a wheel.

Hi Flecc

 

Seems you are looking at this from an old fashioned point of view.

Thing have really changed since needing 30+ spokes.

 

thx

 

Bob

 

Bob

Is there much evidence of the 24 spoke Nexus 8 being developed further ?

 

Many of the touring bikes that would use this hub still seem to favour >30 spokes in the wheel. Very often the spokes are lighter gauge, particularly when made in Europe rather than the Far East.

 

James

Hi

 

The rear wheel on the pro connect is a shimano designed complete wheel package for nexus hub systems. it has 24 spokes arranged in a radial design on the non drive side and 2x design on the drive side. This is because of the size of the hub flange of the nexus hub and the design of the rim. shorter spokes can be tensioned higher and therefore the wheel has less spokes in the design.

 

These spokes are fine with the Proconnect as the weight is only a few kilos more than the conventional version, this will be more variable rider to rider than Pedelecs to Conventional style.

 

Flecc, we have sold double the amount of proconnects compared to the Agattu.

 

Once we receive the wheel back from elder we will determine the exact cause of this case and report back the results. In the meantime we will double check the tension of each spoke before it is delivered.

 

Regards

 

Mark

Technical Manager

50cycles

 

Thanks for that good reply Mark.

Hi Flecc

 

Seems you are looking at this from an old fashioned point of view.

Thing have really changed since needing 30+ spokes.

 

thx

 

Bob

 

As James has remarked Bob, not old fashioned in fact but what Shimano supply as the norm. As I've said earlier, walk around the stock in any large dealers and you'll see how commonplace 32 to 36 spoke wheels are.

 

Once again, less than 30 spokes exists almost entirely on road sport bikes of the kind used by the lycra brigade, and this is an e-bike forum dealing with bikes weighing two to four times as much and used primarily for utility and commuting purposes, working bikes in other words.

 

In that environment logic dictates the use of at least 32 spokes, there being no realisable advantage from using less on such heavy bikes. As I demonstrated above, 80 grams additional wheel weight has no relevance on such bikes.

 

E-bike riders don't generally road race or otherwise compete, but they do often carry large loads of shopping and other items, carry children on child seats, tow heavy trailers and otherwise give their bikes a tough time. They also maintain higher average speeds than unpowered utility bike riders so the bikes take more punishment in that respect too.

 

And even if my view was old fashioned, is old fashioned synonymous with not good? Old fashioned meant a prison population of one tenth of the present level, a youth population who scorned the use of knives as being for cowards, few people owning cars, most riding bikes to get about.

 

Seems to me that being old fashioned is entirely praiseworthy.

.

No problem Scott, as I remarked above, having fewer spokes is no reason for not buying a bike that's liked otherwise, and I have lots of faith in the Kalkhoff products.

 

My point is only questioning the logic of fewer spokes on any make of road bike that's not for sporting competition, there being no advantages other than the sporting image and maybe slightly easier wheel cleaning.

.

Hi Flecc

 

You will be glad to know that these bikes are very heavily tested with weights and extreme vibrations for weeks before bringing them to the market. The Pro connect is purposely designed for the touring market which is renowned for carrying very heavy loads.

 

However we will send our report to Derby Cycles after we receive the wheel or photos. In the meantime we will double check the tension of each spoke before delivery.

 

Best regards

 

Scott

 

Thanks Scott. Support for the Shimano rear wheel in the 24 spoke configuration will need to come through the 50C/Derby Cycles route.

 

The Nexus 8 hub is working very well on my ProConnect and suits the bike well. I have not experienced any problems with the wheel or spokes, but spare parts that are specifc to the wheel are not readily available as yet from regular Shimano sources in the UK.

 

James

more spokes

 

coupla reasons why BMX and mtbs bikes have more spokes... and their riders more fun!?

 

http://assets.loopd.com/RFS/36/e4e5e9f0-8882-4f72-95f1-64681c1f6fc3l.jpg

 

http://www.norconewsletter.com/content/images/06aug/flatland_trick.jpg

 

http://reviews.mtbr.com/files/2008/04/image0118.jpg

 

 

So i think the stresses on a wheel are somewhat different from a battery assisted ride to the annual alottment meeting eh?

Old Fashioned?

 

...few people owning cars, most riding bikes to get about.

 

Seems to me that being old fashioned is entirely praiseworthy.

.

 

That would be bikes without electrical assistance then? not the ones you are all currently enjoying? the ones using modern technology developed by jonny foreigner...

 

Glad i dont remember the good old days! i will get back down the mine now for another 72 hour shift and catch the tram home with a bag of chips and a new suit for two bob and then man the ack ack gun all night....

 

take off them rosy glasses....

coupla reasons why BMX and mtbs bikes have more spokes

 

Hi properlegs

I can see why the wheels need to be stronger for BMX and mtbs, but why do you see it as important to have MORE spokes rather than THICKER spokes ?

 

For less demanding stuff with large 700C wheels, my personal choice is still to have plenty of spokes (say 32 or 36), but thinner gauge. It gives the rim greater all round support, so that an occasional high kerb or deep pothole is less likely to damage the rim.

 

James

 

PS Quite envious of what can be achieved with BMX's and mtbs, properlegs.

spokes again

 

A thick spoke is no stronger than a thin spoke when used properly.... double butted gauge spokes (ie where the the thickness changes along its length) are lighter than standard gauge but just as strong, if not stronger. Thicker spokes would neccesitate larger holes in the rim and hub and weaken the wheel. Also it is the lacing of the spokes that provides the strength.... so more spokes crossing more times builds a much stronger wheel... or less spokes at a higher tension does the same but the design of the rim and hub is different. spoke under more tension are often of a straight pull design, IE no heel, or bend in the spoke. This is the weak point of any wheelbuild and modern wheelsets such as the pro connect shimano wheels run straight pull spokes to increase spoke tension and reduce spoke numbers to lighten the weight...

 

its a black art!

Yep! Wheel-building is more art than science.

 

24 or 36 spokes for the Pro Connect? I've read more than one report on this forum of snapped spokes and spokes coming loose on the Pro Connect - any more and I'm going to conclude that for riders over the mythological 150 lbs, (ie., 200lbs+), might be better upgrading to 36 spoked wheels.

 

However it all hangs together and starts off with the manufacturers stated kgF of force that the rim can handle as a total. Take a quality rim for instance with a total circumferential compressive strength that is able to handle 3200 kgF of force. So with 32 spokes that means 100 kgF for each spoke. The same rim with only 28 spokes would need each spoke tensioned to withstand 114 kgF. The less spokes, the greater the tension needed to maintain the integrity of the wheel when the same rider and frame weight is applied. If a 24 spoke version of the above rim was required the reduced amount of spokes would need to be tensioned even further so that each spoke had to be able to handle 133 kgF.

 

In the opposite direction if the same rim was chosen to house 36 spokes, then the stress and tension can be reduced substantially as more spokes mean only 88 kGf per spoke. So in this instance the 24 spoked version would need spokes tensioned by a staggering 51% greater than that needed for the 36 rim version. It's no coincidence tandem riders favour 48 spokes per wheel to handle their 'double' load.

 

Modern manufacturing process have developed 24 and 18 spoked rims capable of withstanding the massive kgF needed per spoke, that simply wouldn't have been possible when I 'were a lad'.

 

In essence - Less spokes = increased tension. Which in turn demands a stronger rim, otherwise you get reports of spokes 'pulling out'. And in addition stronger hubs are also required to maintain the higher tension required of the spokes.

 

Therefore as the spokes can only be tightened to the maximum circumferential compressive strength of the rim, more spokes won't do any damage if the tension is correspondingly reduced, and beneficially they can then support a greater load because that load is distributed among more spokes.

 

There does exist a 'best ratio' between the number of spokes, spoke diameter, (James's query about thicker spokes), and the cross section of the rim. And it's come about mainly by trail and error throughout the last century, to stand the test of time and that is for 700c wheels, 36 spokes will serve you best - you can still make build them faster and lighter than you ever dreamt possible - for a price, (custom wheel builders).

 

Besides, break a spoke on a 36 spoked wheel and you can cycle home quite safely without any further mishap. Break a spoke on a 24 spoked wheel and the others will go quite rapidly if you continue without replacement/repair.

 

I have been fortunate to have never suffered from broken spokes on any of my bikes that others seem to suffer from on an infrequent basis, (and I'm no lightweight), and apart from my folder they're all hand-built quality 36'ers. (Tell a lie: I once used some secondhand 32 spoked wheels designed for lightweight racing on a touring bike and snapped spokes during the tour, hence my aversion to anything less than 36 spokes).

 

So are 36 wheelsets slow and heavy? Not at all; one of my 60cm large-framed 'fast' road bikes hits the scales a shade under 21 pounds, (9.5 kgms), and it's fitted with 36 spoked wheels, (6' 2" and I weigh well over 200 pounds).

 

P.S. Almost all of my 36 spoked wheelsets have never needed to go back for a 'tune-up' or had to be rebuilt/respoked etc., (One 'fast' set has been in use on and off for over 20 years without ever needing re-truing).

Edited September 16, 200817 yr by Danny-K

 

So i think the stresses on a wheel are somewhat different from a battery assisted ride to the annual alottment meeting eh?

 

I wouldn't know anything about using allotments, but I do know what it's like to be forced into a pothole by vehicle too close in ill maintained lanes. A shock impact is a shock impact. The forces in physics have been well understood for along time, and I'm not aware that BMX has created any new ones.

 

Like DannyK, I don't suffer from broken spokes on my bikes, all having 36 spoked wheels which I've built or retrued.

.

Edited September 16, 200817 yr by flecc

That would be bikes without electrical assistance then? not the ones you are all currently enjoying? the ones using modern technology developed by jonny foreigner...

 

take off them rosy glasses....

 

That's the difference, knowing of today and yesterday, as against only knowing today.

 

Revised, that reads bikes without electrical assistance but often with petrol motor assistance of between 25cc and 50cc. They used the modern technology of the time, developed by Johnny Foreigner and John Bull.

 

No rosy glasses here, just a wide ranging unblinkered and logical view of reality, in which connection, I wonder why my adversaries in this thread avoid the crucial point I've made about fewer spokes?

 

i.e. What is the point when there is no advantage, as I've very clearly shown, and 36 spokes add assurance against failure?

.

A thick spoke is no stronger than a thin spoke when used properly.... double butted gauge spokes (ie where the the thickness changes along its length) are lighter than standard gauge but just as strong, if not stronger. Thicker spokes would neccesitate larger holes in the rim and hub and weaken the wheel. Also it is the lacing of the spokes that provides the strength.... so more spokes crossing more times builds a much stronger wheel... or less spokes at a higher tension does the same but the design of the rim and hub is different. spoke under more tension are often of a straight pull design, IE no heel, or bend in the spoke. This is the weak point of any wheelbuild and modern wheelsets such as the pro connect shimano wheels run straight pull spokes to increase spoke tension and reduce spoke numbers to lighten the weight...

 

its a black art!

 

The ProConnect front wheel uses a straight pull, 24 spoke Shimano wheel.

 

The rear wheel uses 24x traditional 13 gauge spokes in a special pattern described earlier in this thread by Mark - radial on the non-drive side and 2X on the drive side.

 

As Mark says, Shimano will have done their sums to come down to the 24 spoke configuration with the Nexus hub, and it will be interesting to hear the outcome of the 50cycles report.

 

James

Danny-K

 

Thank you very much for the comprehensive post on the relative tensions in 24 spoke wheels vs larger numbers.

 

I can relate particularly to the point about being able to ride home with a broken spoke on say a 36 spoke wheel having suffered a few broken spokes prior to rebuilding the front wheel of my Torq.

 

For info, recommended spoke tensions for the proconnect rear wheel are given here as 900-1300 N (approx 90-130 kgF) on the sprocket side, and 700-1100 N (approx 70-110 kgF) on the non-drive side.

 

This is quite a wide range, and it would be interesting to know whether the higher or lower end is most suitable for the ProConnect.

 

James

Edited September 16, 200817 yr by JamesC

For info, recommended spoke tensions for the proconnect rear wheel are given here as 900-1300 N (approx 90-130 kgF) on the sprocket side, and 700-1100 N (approx 70-110 kgF) on the non-drive side...This is quite a wide range, and it would be interesting to know whether the higher or lower end is most suitable for the ProConnect..

 

Thanks James, that's handy to know.

 

The original post on this thread by Timelord complained of the spoke snapping off at the hub end of the spoke. That could suggest that the spoke 'elbow' at the head of the spoke, where it bends through the hole in the hub flange may be too long, or too sharp an angle, for the tension applied to the spoke, (a common fault when spokes snap at the hub end, and usually sorted by inserting a brass washer to shorten the excessive play in the 'elbow' of the new spoke and the flange head), or poor positioning of the spoke head in the head of the hub during assembly, too thick a flange head for the spoke used or in some cases even the way the spoke patterns cross, rather than a tensile strength issue of the spoke chosen for the wheel.

 

And incorrect spoke tension still can't be ruled out. Too slack and ovalisation of the hole in the hub head can result, inducing movement in the spoke head and thus eventual breakage.

Edited September 16, 200817 yr by Danny-K

The point is having a lighter bike. Which is an advantage for any kind of bike, be it a mountain, road, BMX or pedelec bike. period.

 

There's no "period" about it.

 

Advantage = 0.18% of the weight of the bike in question with a typical 70 kilo rider. At less than two one-thousandths of the weight, it's impossible to detect or measure any advantage. How does that compare with this that you said earlier in the thread, "If you fitted a 36 spoke wheel to a pro connect your going to be adding a ton of weight". In fact it would take 6363 Pro Connects with 36 spoke wheels to add that imperial ton of weight. As an engineer, I deal in facts.

 

Disadvantage = Less wheel strength, as you've acknowledged in giving the reason for standard BMX having more spokes. All other factors equal, the lesser strength is a reality, the advantage as shown, almost mythical.

 

However, perhaps you'd like to tell me of one other realistic full size wheel production e-bike ever that has had less than 30 spokes, other than the Derby Cycles Pro-Connect/Dover model. Even the exceptionally light 17 kilo sporty Cytronex-Trek e-bike has 32 spoke wheels.

.

Edited September 17, 200817 yr by flecc

The point is having a lighter bike. Which is an advantage for any kind of bike, be it a mountain, road, BMX or pedelec bike. period.

 

No, there's no doubt it's a fashion/image thing, not about weight minimising!

 

The weight difference on this bike is not significant, so that is not a consideration. It may be on a professional road or track bike, but that's not a relevant comparison. You've also got to take into account the extra weight that may be needed to incorporate stronger rims to compensate for the missing spokes, so the wheel may not even end up lighter after all!

 

If Derby Cycles really wanted to shave every gramme of excess weight from the Pro-Connect they would be getting rid of quite a few other things including putting even fewer spokes on the front wheel (as on professional road bikes) which bears less weight and so the level of strength required is lower.

 

PS Crossed with Flecc's post

Edited September 17, 200817 yr by frank9755