Thorn Cycles Forum

Technical => Wheels, Tyres and Brakes => Topic started by: ourclarioncall on March 22, 2023, 01:30:28 PM

Title: Higher spoke count less distortion ?
Post by: ourclarioncall on March 22, 2023, 01:30:28 PM: Just saw a video of a guys wheel being spun and wobbling away after breaking a spoke

No idea on specs on the wheel or how many spokes

He was in a bit of a pickle without spare spokes or near a bike shop and his wheel probably wouldn’t last long being ridden.

Just wonder if having a higher spoke count in the 40+ range would stop the wheel distortion as much when a spoke breaks ?

Maybe strong rims help in the equation too?

It’s kind of crazy to me a bombproof bike could have such an Achilles heel like a little fragile spoke

I’ve always liked the idea of over the top 48h rims (even tho I know I don’t need it)
Title: Re: Higher spoke count less distortion ?
Post by: ourclarioncall on March 22, 2023, 01:58:26 PM: Sorry , think I posted this in the wrong section [Fixed! :) -- Dan]
Title: Re: Higher spoke count less distortion ?
Post by: JohnR on March 23, 2023, 09:01:57 AM: If you are really worried about breaking spokes then solid wheels are the solution but you might not like the weight. I can only offer my two experiences with spoke problems.

I hit a big pothole about a week before the end of my supported LEJOG in 2021. The pothole was lurking in the shadows on a downhill and I hadn't seen it. I shook me and the bike (Thorn Mercury) up so I stopped and checked for damage but couldn't see any. Subsequently I noticed a bit of wobble in the front wheel and identified that a spoke was loose but was still in place. I did have some spare spokes but decided to wait and see if the wobble got worse. The bike had the disc brake forks so the wobble didn't affect the braking. There was no change during the remainder of the ride so I left the investigation until I got home when I discovered that the spoke was fine but the head had broken off the nipple. Whether or not that was caused by hitting the pothole is unknown.

Last summer, on a coast to coast ride, one of the leaders (on a borrowed bike) had a rear spoke break at the hub end which meant that it was flapping around. He consulted the bike's owner who said no problem so the broken spoke was bent around some of the other spokes to hold it in place and stayed that way until the end of the ride. That bike also had disc brakes.

If you are in the middle of nowhere with a heavily loaded bike then replacing a spoke, provided you have one of the right size, is a delay but not a show-stopper provided you have the tools. The replacement spoke doesn't need to be perfectly tensioned - it's a matter of taking the wobble out of the rim.
Title: Re: Higher spoke count less distortion ?
Post by: martinf on March 23, 2023, 09:47:19 AM: It is a long time since I broke a spoke. IMO the most important thing is to build the wheels with enough spoke tension. I always check (and correct if necessary) any wheels I have not built myself. In the past couple of decades, the only ones that haven't needed any correction were the wheels supplied by Thorn on my 2012 Raven Tour and the Rohloff wheel they built for my Raven Sport Tour, they must have a good wheel builder.

These 26" wheels dealt OK with up to 123 kg of weight (bike plus rider plus luggage) on a long tour using roads and tracks :

Deore XT hub rear hub, fairly lightweight Mavic 717 rim. Wheel dished for 7-speed cassette. 36 spokes (2 mm stainless steel).
SONdelux front hub, fairly lightweight Mavic 717 rim. 32 spokes (double-butted stainless steel).

A rear wheel for Rohloff will be stronger, as no need for dishing. There shouldn't be much difference in strength between 26" and 650B, 700C.

I have used 28 spoke wheels and light Mavic Open Pro rims for quite a long time with no problems on my old lightweight 700C bike. Max total weight about 105 kg, this bike is only used on metalled roads and bike paths with a good surface.

So I don't think more than 36 spokes are needed, unless the all-up weight is well over 120 kg.
Title: Re: Higher spoke count less distortion ?
Post by: PH on March 23, 2023, 10:44:37 AM: It ought to be possible to true a 32 spoke wheel with a single spoke missing well enough to still use a rim brake, though it might need backing off a bit. Two adjacent spokes could be troublesome regardless of the count, though spacing is important (Rim diameter/spoke count). With a disc brake, you only need to clear the frame/forks. Anyone who's commuted to work at a factory or the like will have seen some shocking wheels still functioning, I'm not recommending it, but people do ride around with multiple spokes missing. I had a Deliveroo rider ask me if their wheel was fixable, I wasn't sure if they were serious, it had two broken spokes and eight pulled through the rim, it was so far out of true the tyre sidewall was worn down to the canvas where it had been rubbing the frame.
I don't carry spare spokes, I've never had a ride ending wheel issue and I don't ride anywhere so remote that it would be a serious problem if I did. I do carry one of these fibre spokes, never tried it, they get mixed reviews, though it's going to be better than nothing.
https://www.sjscycles.co.uk/spokes/fiber-fix-emergency-replacement-spoke/
Title: Re: Higher spoke count less distortion ?
Post by: mickeg on March 23, 2023, 11:53:38 AM: I have only broken spokes on wheels from a 1960s vintage bike. I have never broken a spoke on a wheel that I built.

That said, I carry spare spokes on a tour.

Exception, I did not build the wheels on my road bike, thus I did not know the spoke length, instead I bought a Fiber Fix Emergency Spoke. Ph included a link in his post on where to buy in UK. I have never toured with that bike, but I thought it would be a good idea to carry a fiber fix spoke on a brevet or if I ever use that bike for a credit card tour.

More spokes makes it less likely you will break a spoke. I have carried heavy loads on my 36 spoke wheels, it is unlikely you will benefit much if you had more. That said, Co-Motion, a bike builder in USA makes the Americano which is a solo touring bike, the non-Rohloff version of that bike uses tandem wheels that are 40 spoke. In my opinion the 40 spoke wheels are less important than the tandem rear hub, that is used to build an undished rear wheel. That is the strongest rear wheel I have seen on a derailleur touring bike.

And speaking of dish, there is a reason most touring bikes are built with 135mm rear hubs instead of 130, there is less dish that way. This paragraph shows my ignorance of the newer bikes with thru axle, I have no clue about those wheels.

When I tour on a derailleur fitted bike, I carry the tools to unthread a cassette lock ring. But only once needed to use those tools on a tour.

You are over-thinking this.
Title: Re: Higher spoke count less distortion ?
Post by: ourclarioncall on March 23, 2023, 04:58:52 PM: Thanks Dan for moving this

The wheel in question was 700x42 and 32 spokes.

Ok so by the sounds of it a good quality rim that’s been well spoked? Laced ? Isn’t much of a cause for concern.

But good to have some spare spokes and basic knowledge/experience of how to balance the tension

I did try to true up my wheels a while back but not convinced I improved it at all or much. Seems like you’d need to work at it a bit to keep this skill fresh . Don’t know if it’s coz my wheels are old ? Do they come less responsive ?
Title: Re: Higher spoke count less distortion ?
Post by: ourclarioncall on March 23, 2023, 05:01:26 PM: Thanks again for comments gentlemen

Life is hectic and I’d like to sit down and respond properly to everyone that comments but not easy
Title: Re: Higher spoke count less distortion ?
Post by: steve216c on March 25, 2023, 08:02:08 AM: When I was initially looking into getting a bike with Rohloff I was concerned about wheel strength given my the weight of just over 120kg. On my derailleur bikes I would need to replace broken spokes from time to time, so investing in a Rohloff wheel with less seemed worrisome.

But then someone pointed me to this article https://www.rohloff.de/en/experience/technology-in-detail/wheel-stability (https://www.rohloff.de/en/experience/technology-in-detail/wheel-stability) and my work colleague of around 100kg who’d cycled 30,000km on his Utopia Rohloff hub bike without a single spoke breaking.

When I bought my bike second hand I noticed a broken spoke within the first week. The wheel was still true. I keep a selection of spare spokes from old wheels, found one of the same length and replaced. All ran well till I needed to replace old approx 25,000km old rim with new Andra 30 using old spokes. A couple of the nipples refused to budge when delaying and in my frustration I cut three or four and replaced with new spokes. I’m several thousand km on new 32 spoke rim and mostly old original spokes and no breaks or buckles or problems.

A 32 spoke Rohloff wheel is a tough beast and in my experience way stronger and more stable than derailleur 32 wheels. But given my weight, I’d stick to 36 spoke rear wheels on my derailleur bikes where stability is not so comparatively good.
Title: Re: Higher spoke count less distortion ?
Post by: Andre Jute on March 25, 2023, 09:33:28 AM: Quote from: steve216c on March 25, 2023, 08:02:08 AM
When I was initially looking into getting a bike with Rohloff I was concerned about wheel strength given my the weight of just over 120kg.

Here's a 48-spoke Rohloff wheel designed by Chalo Colina, a Boeing toolmaker, later a bicycle mechanic in Austin TX, who at his fittest weighed "only" 350 pounds. Note that after the drilling, not all the original factory holes are used.
(https://rideyourbike.com/images/rohloff48spoke/rohloff1.jpg)
Photo from https://rideyourbike.com/48spokerohloff.shtml
(which was called Aaron's the last time I checked)
Chalo was instrumental thirteen years ago in me converting from Shimano HGB to Rohloff, and also in me choosing a Utopia Kranich in which to use it. The bike showing off the Rohloff wheel above is by David Bohm, recognisable by the fancy frame end.

As Ecclesiastes says, "Now let us praise famous men."
Title: Re: Higher spoke count less distortion ?
Post by: Andre Jute on March 25, 2023, 09:58:28 AM: Quote from: martinf on March 23, 2023, 09:47:19 AM
I always check (and correct if necessary) any wheels I have not built myself. In the past couple of decades, the only ones that haven't needed any correction were the wheels supplied by Thorn on my 2012 Raven Tour and the Rohloff wheel they built for my Raven Sport Tour, they must have a good wheel builder.

The most shocking wheels I ever received on a new bike came from one of the world's most reputable bike makers on a Gazelle Toulouse. Their spoke tension was all over the place. It took me months to get them just so, because I did it at the halfway point of a ride I took every day rather than all at once. The best wheels I ever had were said to have been built by Keith Bontrager himself as prototypes for my Trek Smover (I'm not vouching for any of this except that the Trek was a prototype which I reengineered lightly to get rid of the thing's hostile sporting pretensions), and the wheels on my Utopia which were computer-built, so I view claims of the superiority of men over machines in wheel building, or the contrary claim, with an equally jaundiced eye. Both the Trek and Utopia wheel sets are still in perfectly stable tune after many years.
Title: Re: Higher spoke count less distortion ?
Post by: martinf on March 25, 2023, 10:20:28 AM: Quote from: Andre Jute on March 25, 2023, 09:33:28 AM
Here's a 48-spoke Rohloff wheel designed by Chalo Colina, a Boeing toolmaker, later a bicycle mechanic in Austin TX, who at his fittest weighed "only" 350 pounds. Note that after the drilling, not all the original factory holes are used.

Rather than spoke breakages I'd be worrying about the Rohloff flange being weakened by the extra holes.

Flange breakage is a known "weakness" of Rohloff hubs, hence the flange reinforcement rings supplied on recent models.
Title: Re: Higher spoke count less distortion ?
Post by: mickeg on March 25, 2023, 11:50:28 AM: Quote from: steve216c on March 25, 2023, 08:02:08 AM
...
A 32 spoke Rohloff wheel is a tough beast and in my experience way stronger and more stable than derailleur 32 wheels. But given my weight, I’d stick to 36 spoke rear wheels on my derailleur bikes where stability is not so comparatively good.

When I built up my Nomad Mk II, Rohloff had started to sell 36 spoke hubs too. That is what I bought. Maybe 32 is enough, but for a rear wheel on a heavy touring bike, in my opinion there was zero downside to ordering a 36 spoke Rohloff hub instead.

I damaged a spoke, somehow the nipple got loose but I tightened it up again and had no problem. You can see that one spoke is not straight, has a bend in it in the photo. Later at home I replaced the spoke and nipple, just to make sure that it would not give me any problems.
Title: Re: Higher spoke count less distortion ?
Post by: Andre Jute on March 26, 2023, 03:55:45 AM: Quote from: martinf on March 25, 2023, 10:20:28 AM
Quote from: Andre Jute on March 25, 2023, 09:33:28 AM
Here's a 48-spoke Rohloff wheel designed by Chalo Colina, a Boeing toolmaker, later a bicycle mechanic in Austin TX, who at his fittest weighed "only" 350 pounds. Note that after the drilling, not all the original factory holes are used.

Rather than spoke breakages I'd be worrying about the Rohloff flange being weakened by the extra holes.

Flange breakage is a known "weakness" of Rohloff hubs, hence the flange reinforcement rings supplied on recent models.

Thanks, Martin. I'm not particularly recommending these 48-spoke Rohloffs, merely mentioning that they exist. Potential users should do their own diligence. However, these 48 spoke wheels have been going for at least 13 years since I first discovered their existence, plus however many years that they were available before I discovered them. I believe that, while first designed to accommodate an exceptionally heavy rider, and the parade bicycles (floats) and bicycle-mounted mobile convenience food stands he designs and builds, they are used for touring tandems.

I have in the past loaded my own bike to pretty near its 170kg load limit with painting gear or liquor shopping, but even though some of the roads are rough (potholes), I have never felt a stronger wheel than 32 or 36 spokes to be necessary.
Title: Re: Higher spoke count less distortion ?
Post by: martinf on March 26, 2023, 07:56:07 AM: For an extra-strong wheel, an alternative to a higher spoke count could be to use single-butted spokes such as Sapim Strong.

These are thicker at the hub end, and then taper to the standard 2 mm size so that they fit normal rims.

No good for Rohloff, as the spoke holes in the flanges are too small, but they would work with Shimano Nexus 8 Premium hubs, although I have never bothered.

The tandem I once had came with a moped-grade rear wheel with thick 13g spokes on an Atom drum brake hub and steel rim.

I wanted an alloy rim for decent rim braking, so I used single-butted spokes when I rebuilt the wheel, mainly because they fitted the spoke holes better than normal spokes.
Title: Re: Higher spoke count less distortion ?
Post by: PH on March 26, 2023, 06:41:07 PM: Quote from: martinf on March 25, 2023, 10:20:28 AM

Rather than spoke breakages I'd be worrying about the Rohloff flange being weakened by the extra holes.

Flange breakage is a known "weakness" of Rohloff hubs, hence the flange reinforcement rings supplied on recent models.
Indeed, I broke two :-\
I haven't heard of any lately though, so I'm wondering if there's other improvement along with the support rings. I know Rohloff have made slight design changes to the shell over the years, and the building advice has also varied, maybe the spate of flange breakages was part of a learning curve.
It isn't only a Rohloff thing of course, all flanges can break, I was on a ride with a group just before the pandemic when someone had about a third of the drive-side snap off, on a relatively new posh hub, ride over for them. Apparently Shimano hubs are better than most as they're forged rather than machined, something that's only viable with Shimano type volumes.