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 Post subject: Are Wide rims too wide?
PostPosted: Sat Jun 13, 2015 2:35 pm 
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The HED ardennes plus 25.4mm, Pacenti SL23 @ 24mm and Archetype 23mm are all wide enough to be above above the recommended ERTRO size for fitting 23mm-25mm tyres. The HED+ based on its internal width of 20mm, should really have a tyre no narrower than 32mm. The Pacenti internal is 18mm, and Archetype 17.5mm.

Mavic have just announced a new Ksyrium range with wider rims, and have made their rims just a bit wider than they were, and appear in their marketing to say that the wider rims, with 23-25mm tyres are dangerous.

Mavic say 19mm rim should have no smaller than 28mm & 17mm rim no smaller than 25mm. Strange really as they think nothing is wrong with fitting a 55mm tyre to one of their narrow MTB rims.


With every upside, there is usually a downside. With wide rims what is the downside? All I read says they are better at everything, and some such as the new Pacenti SL23 are even lighter than standard rims like some DT & Open pro's.

Also, Forgetting the price, and weights, which is the best rim?

I have read & Heard;

HED Ardennes plus, is very well made, very round, and excellent braking surface, but maybe just a bit too wide, for brakes that are optimised for 23mm (Dura Ace 9000).

Pacenti is also well made, but braking surface can pulse a little, and cracked rims are not unknown, but is a little lighter.

Archetype, is very strong, well made, and excellent braking, possibly less aero, a little heavier


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PostPosted: Sat Jun 13, 2015 4:16 pm 
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yes


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Posted: Sat Jun 13, 2015 4:16 pm 


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PostPosted: Sat Jun 13, 2015 4:50 pm 
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The downside? The tires!

The problem with wide rims (and, incidentally, deep rim beds with 'high', aero sides) is that you need to use larger section or risk pinch flats. Right now, that means fewer options and less availability. In addition, the 'feel' of a 25-section tire is different than a 22 or 23-section tire. Personally, I prefer the feel of a 22or 23. To me, they just feel like they 'fall over' more predictably. It's kind of hard to pin down or explain.

For awhile there, I though that a 22 or 23 front with 25 rear was the answer, but rims kept getting wider and wider, so that doesn't seem to work as well anymore.

I think the consensus is that the wider rims are faster. Further, the large-section tires roll faster and are more comfy. I don't know what the answer is. I guess we just have to live with it. Francois is going to make a pant-load on 25-section tubulars, that's for sure.


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PostPosted: Sat Jun 13, 2015 5:16 pm 
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I would trust what any other company on the planet says before believing Mavic.


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PostPosted: Sat Jun 13, 2015 5:47 pm 
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This is a good question, and I've been pondering it for several years actually, ever since wider became a trend. I pretty much run tubulars all the time now, and the issues aren't as great as they are for clinchers. For a wider tubular, the rim bed actually has to have a larger radius for a good fit, which may render it shallower, not deeper. I noticed when removing a 25mm Arrenberg or Roubaix off an Ambrosio Nemesis rim (standard width, relatively deep bed compared to some others), the bond is far greater at the edges than in the middle. It's good that the bond is strong at the edges where it needs to be, but with a 22 or 23mm tire on the same rim, the bond is very strong across the entire rim bed. Hence the reason for the "Belgian" method of building up the middle of a tubular rim to accommodate larger volume tires, very common in Cyclocross, or at least it used to be. And a 25mm tubular is about as big as I would ever want to go for a high performance road tire. Being a bigger guy, I felt like "ok, I bet riding this 25mm is what the little guys feel when riding a 22 or 23mm). If that's the case, I would even put forth that a lot of you smaller guys are getting duped into thinking you need a bigger tire/rim. For all out speed, I feel the previous generation (pre 2015) of Boras with a 23mm tire mounted on it feels faster than the new ones with a 25mm tire, providing you have the right pressure appropriate for your weight AND the tire being used. It's a moot point for me, because overall I like the feel and handling of a 25mm tire on the road for my weight. I think I get what Geoff means when he talks about a more predictable "fall over". Going bigger than you need can get a bit "mushy" feeling and you shouldn't confuse comfort with control. As with anything, you need to find the right balance for you as an individual.

Move to clinchers and it's a whole different can of worms. Different width rims can and do create an entirely different profile for the exact same tire. You almost have to try the combination out to see how they work together and in your frame and with your brakes. There could be clearance issues even with a 25mm tire on some of the wider rims in certain frames. But the wider rims do seem to add to some stability, if my experience with the new Boras at 24.2mm wider compared to the previous Boras is any indication. And the current crop of caliper brakes were most certainly designed with the older standard width in mind, so you need to be a little careful there as well.

So, in summary I think yes, a road rim can be too wide, and the wider it gets the more careful you have to be in making sure all the various parameters surrounding it work together... frame clearance, brake clearance, clincher type/size, etc.

Lot of stuff happening in the industry at the moment. Some stuff will stick. Some will be looked back on with comments like "how silly was that" (brakes mounted underneath the bottom bracket comes to mind). But it will be interesting to see if things actually settle anywhere or if it becomes a free for all with choices all over the board so you can get whatever works for you and be damned what the other guy is running, which is fine too.

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Last edited by Calnago on Sat Jun 13, 2015 6:41 pm, edited 1 time in total.

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PostPosted: Sat Jun 13, 2015 6:30 pm 
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Nice post.
Some changes do make sense and are here to stay. Other trends have already or will disappear in a few years.

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PostPosted: Sat Jun 13, 2015 8:23 pm 
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Calnago wrote:
Some stuff will stick. Some will be looked back on with comments like "how silly was that" .


The placebo effect + marketing. Once the public became sold on "wide is better", then even wider must be more better, right? Even though the benefits of going wide are tiny, the only downside is a little weight. So it will probably stick somewhere around 24mm.

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PostPosted: Sat Jun 13, 2015 10:19 pm 
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I've wondered how ERTRO was derived anyhow. Or if there's actually any engineering sense to it versus a bunch of guys saying "it's ridiculous to put a 25mm tire on a 21mm rim!" without any further thought. Or, say, standards developed in the 1960's and never updated to acknowledge how much better stuff is nowadays.

That said, we're not seeing the masses move to tires much bigger than 25's, at least for the road, so rim width is probably stabilizing.


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PostPosted: Sun Jun 14, 2015 8:42 am 
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I was thinking about this the other day as I was at the end of a long gravel hills ride and my 23mm GP4000s sidewall vertically split completely from the bead to the tread. Given they ran out to 25.5mm on the Pacenti Sl23 rims, hence clearly stretched, I think it's fair to say that 25mm tyres should be a requisite for the wider rims. Now riding the Spec. Roubaix pro 23/25mm which aren't as tight and run the same width as the Conti's.

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PostPosted: Sun Jun 14, 2015 12:03 pm 
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I definitely think there is such a thing as too wide.

While I don't deny the a tyre can 'stretch' to be a little wider I think the main reason for a '23mm' tyre measuring 25.5mm on a wide rim is that it's base is spread wider, therefore starts out wider.

It also means that it will have a less rounded profile with sidewalls coming straighter up from the rim. For me (Hed Belgium Plus with GP4000S 25mm) I find tipping into a steep/fast/tight corner less predictable as the edge isn't as progressive (round). Instead the 'squarer' shape drops away quickly on the edges. All else being equal (hubs, spoke type/number/pattern, tyres) I am a more confident (and faster) technical descender on a narrower rim than the Hed Belgium Plus.

I won't deny that a bigger air volume from the wider rim is more comfortable and generally better grip due to the ability to run lower pressures. But they are not better for fast descending.

I won't be going back to the silly narrow of the Mavic Open Pro genre but somewhere in between them and Hed Belgium Plus is right for me I think.

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PostPosted: Sun Jun 14, 2015 3:04 pm 
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My Conti GP4000S II 23mm tires measure wider on a narrow rim than on a wider rim. For example they measure 25mm on my 20.5mm (15c ETRTO) Shamal clinchers and 24.5mm on my 24.2mm (17c ETRTO) Bora clinchers. Both pumped to 100psi.

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PostPosted: Sun Jun 14, 2015 4:41 pm 
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Titanium22 wrote:
Strange really as they think nothing is wrong with fitting a 55mm tyre to one of their narrow MTB rims.


If you haven't kind of noticed road tyres carry a lot more pressure than MTB tyres do.


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PostPosted: Tue Jun 16, 2015 8:01 pm 
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I'm quickly learning that there is a tipping point in terms of width. Just posted about this in the tire height thread as well. Recently had a set of Pacenti SL23 rims built up with the intention of running 25c tires on them. While riding them, something never felt quite right. It felt as someone above noted 'mushy'. Couldn't put my finger on it. Then I also noticed that the combination of the wide rim bed (inside and out) with the 25c (Michelin Pro 4) tire caused clearance issues on one of my bikes. The tire becomes so big on that combo that the fork bottoms out on the top of the tire.

So now I've switched to a 23c tire on the Pacenti rim for the front and a 25c for the back. Hopefully this gets rid of that mushy feeling as well as aleviates clearance issues because I love the bike and the wheels.


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Posted: Tue Jun 16, 2015 8:01 pm 


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PostPosted: Fri Jun 19, 2015 12:30 pm 
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I have riding 23mm tyres on 25mm wide rims for two years. Pinch flats have not happened so I think most of this thread is a bit over done. The ERTRO tyre width/rim width recommendation are guidance at best. As always you have to try the tyre and see how its sits and if you like how it feels.

Never had a mushy feeling with tyres on wide rims. Got 30mm tyres on a set of pacenti's on one bike runing 60 psi. They do not feel mushy in the slightest. comfortable yes though in fact I barley notice potholes now grip is good too. I have had more issues with grip on narrow tyres than I do on wider ones.

Fit a conti GP4000s tyre to a archetype rim (17.5mm internal width) and they measure 27mm so something is up with yours on bora rims.

Sidewall on tyres split on narrower rims, seen it happen to other and it has happened to me so saying it was down to the wider rim on a sample of one is the classic human thing of seeing a result you dont like and then looking for a reason and you pick the closest. The cause and effect may not be there though.

I believe you can safely run 23mm tyres on wider rim (as there is no evidence that you can't safely) and like wise you can run wider ones. Personally I would suggest running the widest tyre you have clearance for again you have to try and see what you can get away with.

I am not sure anything wider than the current HED rim or Pacenti SL23 is of benefit to road width tyres but there is one way to find out.

I also like tubs in 25mm width and they seem perfect but my TT bike wont take a tyre that wide which is sad.

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