reasonably priced road disc brake wheels - experience sought

BBB wrote:

Slight misunderstanding. When I first replied I used external widths as this is what I believe most of people are more familiar with that, then I started quoting internal dimensions to be more precise.
I realise how wide "proper" Mtb rims/wheels are as I wouldn't use anything narrower than 35mm myself but the ones within OP's budget typically are ERTO 622-19C...

Aye, 622-19 would be great with 28mm tyres which sound a good choice for the OP.

BBB wrote:

As for Cannondale Bad Boys, 25mm is a stupid size (just a strong personal opinion) for urban commuting (or even training on some roads) regardless of the rim width.

I'd ideally not use 25mm for commuting either, but run 25mm Open Paves on 622-17 on the 'road' bike which come up a nice bit over 27mm and work well for general abuse on tarmac and light use off it.

BBB wrote:

The only measurement relevant in this discussion is inner width measured at the the bead hook(s).

Precisely, so when you wrote

but look also at 29er MTB wheels. Many of them will have 25-26mm wide rims so no problems with using 25mm or 28mm or wider tyres.

..I said I really wouldn't recommend it, and have been giving you figures based on internal rim widths ever since.

BBB wrote:

The new generation of 23mm rims measure around 17mm inside and the 25mm ones listed above have 19-21mm inner width which is exactly the same as many MTB XC wheels.

Most 29er MTB wheels have internal diameter much higher than 19mm, which is about as wide i'd feel comfy putting a 25mm tyre on and a bit more than recommended elsewhere.

BBB wrote:

Someone tell those guys they are doing it wrong! Their rims have the same or wider inner width that many mtb wheelsets (typically 24.5-25mm and 19mm inner)

http://www.bikeradar.com/road/gear/category/components/wheel-sets/produc...

http://road.cc/content/review/132864-spin-koppenberg-max25-25mm-wide-fat...

http://www.planetx.co.uk/i/q/RIPXCT45CCL/planet-x-ct45-carbon-clincher-rim

..perhaps you should try and understand how rims are measured... then review what i've been trying to say.

BBB wrote:

I think it's a similar situation to running non-tubeless mtb tyres... tubeless with a bit of sealant, gaffer or Gorilla tape or split tube ghetto method. It looks and sounds dodgy, it shouldn't work,

No, no it really isn't similar...

BBB wrote:

Mavic says that it can kill you... (because they want you to buy their expensive UST rims and ignore what consumers really want) but... it works and plenty of people enjoy the benefits.

Nothing to do with their over-priced rims - it's the tyre width they're talking and they could have chosen any size for their new tyre with no additional cost to them. They have nothing to gain by choosing a particular width beyond technical merit.

BBB wrote:

Like I said before many people have been using narrow slicks with various mtb rims for ages and I haven't heard any stories about spontaneous blowouts. What Mavic and many other companies say you can or can't run is dictated largely their legal and marketing teams IMO.

The guys from Continental would be terrified if they knew that I'm running their 28mm (32mm) slick tubeless at 50PSI at the front... but I know it works

I really doubt they would - however you're still completely missing the point but, hey, whatever - i'll leave the thread and let the OP hopefully get some more useful information about what they actually asked about.

BBB wrote:

I don't really get it.

Bead security issue? Plenty of people run 1" ish slicks on 26" rims at 100PSI and they are still alive.
The width of mtb rims isn't an issue but an ADVANTAGE. Nowadays it's normal to run 23mm rubber on 25mm rims so logically +25mm tyres will spread better on wider rims.
Currently I run Conti Grand Prix 28mm mtb slicks (exactly the same as their 700C cousins) on 28mm Stans rims. They stretch to around 31-32mm and they handle beautifully.
The max pressure warnings on mtb rims are about wide mtb tyres run tubeless. It's only to prevent some fools to put 60PSI in their 2.35" tyres;-) You can still run narrower tyres at high pressure without an issue.

It looks like anything with a MTB label on it is evil in a road cycling world;-)

Not at all - it's just that it seems that there is some feedback to suggest that it may not be the best mix and, potentially, dangerous. I run wide road rims and narrow and wide tyres and enjoy the benefits - but i'm also willing to listen to advice from others who have thought about it, and tested it, more than me. Again, i've done - and do - things that may not be recommended but it's a personal choice and judgement based on the rims, tyres and where i'm going to be riding (hence pressure). I'm not comfortable with telling someone else to try something that is explicitly advised against by those that may have much more of a clue than me. 23mm tyres on 25mm rims is hardly normal either.

Back to why... my take would be that given the way the a bead hooks into a rim I think it's quite clear that the relationship between the width of the rim and tyre will dictate how much the tyre will need deform to adopt a certain shape.

If you have a narrow rim and a wide tyre the issue is normally the light-bulb stress (double curvature) and pinch flats. If it's a very wide rim and a narrower tyre then to engage the bead in the hook securely then i'd imagine it's the extra strain in the side-walls.. think about the angle of the bead/sidewall and the rim hook - doubly so with tubeless (which I use), you really want the two the match more the higher the pressure.

Anyway, not matter what you and I might think, maybe have a look at what people are saying why it's not ideal to go to far either way with fat tyre/narrow rim or vice versa.

BBB wrote:

Bead security issue? Plenty of people run 1" ish slicks on 26" rims at 100PSI and they are still alive.

I'm one of them. Used the Specialized 25mm Turbos on a variety of 26" rims since the 90s without any un-seating problems. They were really tough to get on a few rim combinations, so zero chance of them coming off.

BBB wrote:

There is no reason why not.
25mm tyres will easily go on 25 or even 26mm rims. Pressure isn't an issue either when using with tubes.
I managed to put 28mm Schwalbe One tubeless tyres on 28mm Superstar MTB rims. The tyres stretched to wonderful 30-32mm

They can fit, and they may be alright but it's not recommended for bead security reasons and ride quality, e.g. from the road.cc review of the Mavic All Road

17mm is not as wide as some, so why haven't Mavic gone wider? It's all to do with ISO norms. ISO 5775 defines the recommended tyre widths for different widths of rim, based on the security of the bead on the rim at a certain trye pressure: too narrow a tyre, or too wide, and the bead may not seat properly leading to a danger of the tyre blowing off the rim. Which would be bad. Mavic have been doing their own testing too, and they're pretty confident ISO's numbers are good. Look down the table and you'll see that 17mm is the widest rim that will accommodate a 25mm tyre; any wider and 28mm is the minimum recommended width.

or the CTC discussion of rim/tyre widths

Another reason not to exceed the 2.2 limit on road is that a more bulbous tyre can deflect sideways with a noticeable effect on control and roadholding. Conversely, fitting a tyre of less than 1.4 times the rim section will result in a harsh ride and more rolling drag than a larger tyre at the same pressure.

I've used various non-recommended combinations and i'm still here (currently) but that is my choice and it is definitely not something i'd recommend to anyone else. That said, I really like your tyre choice

BBB wrote:

I can't recommend any particular model as I never use factory wheels but look also at 29er MTB wheels. Many of them will have 25-26mm wide rims so no problems with using 25mm or 28mm or wider tyres. Weight will be similar.

I'd be really careful trying to use MTB rims with road tyres that narrow, especially the 25mm.