Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

For discussions about bikes and equipment.
Valbrona
Posts: 2187
Joined: 7 Feb 2011, 4:49pm

Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Valbrona » 21 May 2019, 4:28pm

I want new wheels. I don't want any spoke breakages during long, unladen rides in the high Alps on a lightweight road bike.

A wheel with 32mm deep rims would have shorter spokes than one with 23mm deep rims, obviously. Hubs/spokes/spoke counts are the same.

But do shorter spokes mean less chance of spoke breakages? Or are longer spokes better at 'soaking up' stresses?

Thanks.
Last edited by Valbrona on 21 May 2019, 8:36pm, edited 1 time in total.
I should coco.

Brucey
Posts: 34265
Joined: 4 Jan 2012, 6:25pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Brucey » 21 May 2019, 5:01pm

the fact that the deeper rim is (all things being equal) stiffer is probably more important than any stiffness difference in the spokes per se.

The way the wheels are built (by which I mean how the spokes fit and how the wheel is stress-relieved) is more important still, and you can't see that or always predict it either.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

pq
Posts: 952
Joined: 12 Nov 2007, 11:41pm
Location: St Antonin Noble Val, France
Contact:

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby pq » 21 May 2019, 9:15pm

To add to what Brucey has already said, to choose between those options I'd base it on what sort of ride quality you want. My road bike rides very well with deep rims because the frame is compliant. If the frame was very rigid I'd be looking at shallow, more compliant rims.
One link to your website is enough. G

User avatar
The utility cyclist
Posts: 2225
Joined: 22 Aug 2016, 12:28pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby The utility cyclist » 22 May 2019, 12:12am

Valbrona wrote:I want new wheels. I don't want any spoke breakages during long, unladen rides in the high Alps on a lightweight road bike.

A wheel with 32mm deep rims would have shorter spokes than one with 23mm deep rims, obviously. Hubs/spokes/spoke counts are the same.

But do shorter spokes mean less chance of spoke breakages? Or are longer spokes better at 'soaking up' stresses?

Thanks.

IMO you're stressing far too much about this, buy some good quality wheels whether they are hand or factory built and simply ride them.
Even when I was rear ended in a hit and run the spokes of the rear wheel didn't break (32hole Dura Ace hub/DT Swiss spokes.Open pro rim), I've ridden 24/20 38mm deep carbon wheels at 107kg using 22mm tyres, no spoke breakages there either. I think the last spoke I broke was 12 years ago and that was on the commuter/utility bike, the wheel was already second hand when it came to me and I was banging it around fully loaded as usual and hit the edge of a pothole I didn't see until too late.

David9694
Posts: 268
Joined: 10 Feb 2018, 8:42am

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby David9694 » 22 May 2019, 9:20am

If you are going deep section rims, don’t forget to pack those 60mm valve stem inner tubes. And do a few miles locally on your choice before setting out.

You can always take some spare spokes with you for peace of mind.

User avatar
531colin
Posts: 12395
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby 531colin » 23 May 2019, 9:22pm

Some random thoughts...
As Brucey says, you shouldn't expect to break spokes anyway. If the wheelset is adequately specified for the job and properly built and stress-relieved, then the spokes should outlast more than one rim, with rim brakes wearing the rim.
A stiff rim will "share out" loads between more spokes than a flexible rim.
Thin spokes will "share out" loads between more spokes than thick (stiff) spokes.
"sharing out" loads will reduce the load on individual spokes, so there is less chance of the rim cracking at the spoke hole, or spoke fatigue.
Jobst Brandt's book on wheels was first published in 1981, long before modern deep section rims. Brandt calculated that a 50Kg load at the axle would produce a maximum deflection of the rim measuring 0.15mm at the bottom of the rim. If I wanted to soften the ride of an overly-stiff frame, wheels are not where I would look. ..wheels are quite staggeringly rigid in a vertical plane.
If you are going for 11 speed with 130mm OLN, then an offset rear rim is useful because it reduces the differential in spoke tension between the left and right side spokes; its also useful in a 10 speed 130mm OLN wheel with a light rim, as is threadlock on the left spoke nipples.

Jamesh
Posts: 453
Joined: 2 Jan 2017, 5:56pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Jamesh » 24 May 2019, 12:03am

If riding in the Alps I think something like cero ar24 would be a good budget choice?

Perhaps not if a heavier rider.

If the hills are lower than 6% pros (or probably 4% lesser mortals) iirk then aero trumps weight but in the Yorkshire dales weight seems to make more of a difference on steeper hills.

User avatar
531colin
Posts: 12395
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby 531colin » 24 May 2019, 9:36am

When people want to "buy" performance, weight is often the first thing they look at. What might you save on a wheelset? 100 grams? Not much as a percentage of the all-up weight of bike and rider, you would do better by emptying your bottle at the bottom of a climb.
A long time ago, when I was stronger and wheels and frames were floppier, I could make the rear brake blocks rub the rim by pedalling hard, and the pros might release the back brake Q/R on a long climb. Impossible to calculate how much effort is wasted by flexing stuff, or if a stiffer wheelset would be better than a light one?

pwa
Posts: 9614
Joined: 2 Oct 2011, 8:55pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby pwa » 24 May 2019, 9:48am

I know there are differing views about this but I feel that I generally make faster progress on lighter wheels, and I reason that weight close to the outer edge of the rotating circle, i.e. tyre and rim, is more of a burden than weight close to the centre, i.e. the hub. Spokes are somewhere in between in influence. If I am right, a heavy rim might slow you down more than a heavy hub. Something to add to the mix of considerations.

Samuel D
Posts: 2699
Joined: 8 Mar 2015, 11:05pm
Location: Paris

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Samuel D » 24 May 2019, 10:00am

pwa wrote:I know there are differing views about this but I feel that I generally make faster progress on lighter wheels, and I reason that weight close to the outer edge of the rotating circle, i.e. tyre and rim, is more of a burden than weight close to the centre, i.e. the hub.

This is true but if you calculate the effect, weight at the very periphery of the wheel counts for only twice the weight at the hub (or bicycle frame or rider’s belly), and that’s only when accelerating. So saving 100 g on the tyres counts for saving 200 g at the hub when accelerating. Still not much. And as soon as you’re up to speed, or yo-yoing in speed without touching the brakes (as when climbing), it makes no difference where the weight is.

pwa
Posts: 9614
Joined: 2 Oct 2011, 8:55pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby pwa » 24 May 2019, 10:22am

Samuel D wrote:
pwa wrote:I know there are differing views about this but I feel that I generally make faster progress on lighter wheels, and I reason that weight close to the outer edge of the rotating circle, i.e. tyre and rim, is more of a burden than weight close to the centre, i.e. the hub.

This is true but if you calculate the effect, weight at the very periphery of the wheel counts for only twice the weight at the hub (or bicycle frame or rider’s belly), and that’s only when accelerating. So saving 100 g on the tyres counts for saving 200 g at the hub when accelerating. Still not much. And as soon as you’re up to speed, or yo-yoing in speed without touching the brakes (as when climbing), it makes no difference where the weight is.

I think the yo-yoing of speed when climbing a steep hill means a small acceleration with each half crank rotation, and a small but cumulative effect of that extra mass at the periphery of the wheel. This is my explanation for the fact that I have found that in hilly terrain in Wales I get around with greater ease with lighter tyres and wheels, though I never go so light that the structure cannot reliably cope with my weight. My idea of light is 32/36 spoke with Open Pros and 25mm tyres, as opposed to 36/36 with heavier touring rims and 35mm Hypers.

Samuel D
Posts: 2699
Joined: 8 Mar 2015, 11:05pm
Location: Paris

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Samuel D » 24 May 2019, 5:52pm

When yo-yoing up a hill the easier acceleration of a lower-rotating-mass wheel is exactly offset by its slowing down more quickly. In other words with lighter wheels the yo-yo is more pronounced (which theoretically causes more loses to aerodynamic drag for a given average speed, not that you’d notice).

Lighter wheels do climb better in proportion to how much lighter they are, but you’d achieve the same benefit by losing the weight from anywhere else.

User avatar
The utility cyclist
Posts: 2225
Joined: 22 Aug 2016, 12:28pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby The utility cyclist » 24 May 2019, 6:52pm

531colin wrote:When people want to "buy" performance, weight is often the first thing they look at. What might you save on a wheelset? 100 grams? Not much as a percentage of the all-up weight of bike and rider, you would do better by emptying your bottle at the bottom of a climb.
A long time ago, when I was stronger and wheels and frames were floppier, I could make the rear brake blocks rub the rim by pedalling hard, and the pros might release the back brake Q/R on a long climb. Impossible to calculate how much effort is wasted by flexing stuff, or if a stiffer wheelset would be better than a light one?

A lot more than that, a set of 105 hubs with say 32 hole Rigida Chrina is over 2000g excluding the QR, my lightweight tubs are 1200g/1680g incl tyres my 50mm deep section tubs are 1847g total with a 27mm rear/25mm front, there were lighter tyres I could have bought but went for something with decent puncture resistance.

So, IMO no you would not be better off emptying your bottle at the bottom of a climb :?, the weight albeit a small saving overall does have a much greater impact than simply shedding weight that is passive on the bike (you'll also need the contents of your water bottle anyway so your 'solution' is rather moot. The performance improvement also relates to the quality/weight of the tubes, the tyres and of course having the correct tyre pressures too,

I had a bit of a giggle by putting my 'heavy' 38mm carbon wheels on my 1959 Carlton (it'd had the rear spread at some point before I got it so it's 130mm OLN) it usually has a pair of fairly light Weinmann hookless clinchers with Michelin tyres, the hubs are beautifully smooth Sunshine/Sansin hubs. The Sunshine's are smoother than a pair of 105s, the wheels are about the same as the aforementioned 105/chrina's, the difference between them and ease of being able to accelerate quicker was very noticeable, riding up hills, well I don't ride the bike as much as I used to but going up one of the local to me short routes with a couple of short digs felt to me that losing the additional 300g-400g per wheel made a difference, how much I don't know, but that's the other factor, in your mind you think they are better/faster, so are more likely to ride with more gusto on top of that or simply feel better about riding something that is 'nicer' and/or lighter.

ATEOTD if someone spends £4500 on a set of wheels and it doesn't make them any faster, so what, that's their business, if it saves them 10 seconds over xx miles then that's a result and for them to decide if it was worth it, there's far too many on here who use insulting language toward people who spend a lot of money on bikes/components, I find these people to be particularly obnoxious.

Brucey
Posts: 34265
Joined: 4 Jan 2012, 6:25pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Brucey » 24 May 2019, 9:34pm

light wheels and tyres nearly always feel nicer to ride on but the difference is smallest when going up a nice smooth climb and actually measuring much difference in speed is quite another thing.

No one mentioned wheel cost as a factor but IMHO wheels are only one step away from tyres in that (especially if they are built light) they are relatively easily damaged and should be viewed almost as consumables. Well, the rims ought to be viewed as consumables, and that means the wheels if you can't easily replace the rims.

FWIW spokes break by fatigue and occasional sudden impacts may be the coup de grace for spokes that are already cracked but they don't contribute greatly to the overall fatigue loading, and nor do they cause good spokes to suddenly fail.

For unladen riding in the alps I don't think the requirements for the rims and spoking are very much different from a good set of training wheels. I personally wouldn't favour a low spoke count or especially deep rims. Deep rims can catch a gust of wind worse than shallow rims and this is potentially dangerous; it is windier than normal over many passes and yet it is more important than normal to hold your line accurately on the road too. I don't think any 'aero benefits' are worth having in this application either; going uphill the effects are slight and going downhill more aero drag means you use the brakes less which isn't necessarily a bad thing.

Thus I'd spec wheels in which I could easily change a spoke and/or be able to tolerate a broken spoke for the remainder of a day's ride; not because I'd expect to break any spokes but because there is little or no advantage in having wheels that are not like this. Ditto I'd choose a rim that I could easily replace if needs be. If I was keen to save weight then I'd probably choose to save weight in the hubs (eg using DT ones), whilst understanding that all things being equal, an aluminium freehub body isn't likely to last as long as a steel one. When considering the rim weight, I'd bear in mind that even an extra 50g buys an awful lot of extra strength and stiffness. I'd choose 32F/36R for a bombproof set and 28F/32R for a set that wasn't quite as strong. I'd stick with same spoke count front and rear if I didn't want to carry more than one length of spare spoke. A rim weight of between 440 and 490g would be 'about right'. Like Colin says an offset rear rim is worth having too.

Obviously not everyone will make the same choices or have the same reasons for so doing but those would be mine. 'Marginal gains' is all very well but if it also results in 'marginal reliability' then you have made a poor choice for that application.... BTW the choices for those wheels would also be greatly affected by what I'd intend to do with them the other 50 weeks of the year too.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Samuel D
Posts: 2699
Joined: 8 Mar 2015, 11:05pm
Location: Paris

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Samuel D » 24 May 2019, 10:06pm

Brucey wrote:I personally wouldn't favour a low spoke count or especially deep rims. Deep rims can catch a gust of wind worse than shallow rims and this is potentially dangerous; it is windier than normal over many passes and yet it is more important than normal to hold your line accurately on the road too.

And what goes up must come down, so mountain riding also produces high riding speeds at times. The faster you go, the greater is the force exerted by the crosswind.

I found this hard to believe even though it certainly matched my experience of being most affected by crosswinds when descending. But then I found an article by David Norwood called “Car in a Crosswind” that explains it neatly.

I notice the best-informed professional racing teams (e.g. Sky now Ineos) don’t use deep-section rims on mountain stages, even though the bicycles could hit the UCI weight limit with those. I believe the effects of even light crosswinds at 100 km/h, just when you need to steer most precisely, is the main reason.