ddub

I don't know how we ever rode those nasty 19s. ;-)

JoeO

Operator error? It's not difficult to put in a wheel. And I've certainly never ever had the experience of taking out my rear C24 and finding it was somehow not set properly.

JoeO

There is no prohibition or even recommendation from Cannondale to *not* run 25s. The Cannondale rep was fully aware of the wheels and tires I used. In fact, the guy at the shop told me he came in and looked at it and immediately agreed to replace it.

JoeO

I should say that the replacement (which I just picked up today) is not a more recent model but rather *exactly* the same frame as I had before. The 2015 Black Inc Nano. So I'm in the same boat as before

Abe_Froman

If you can't run 25mm tires....that seems like a design error, not operator error.

Dean V

It is an operator error. The operator tried to run wider tyres than what the frame was designed for.

JoeO

No, the operator did not, as confirmed Cannondale

Abe_Froman

Imo, any bike that cant take at least 25mm tires is in grave danger of false advertising the idea of a pneumatic tire. Not really enough air in there to qualify as pneumatic lol.

Dean V

I have a number of bikes and none of the specs say *do not run 28s*. Does that mean it should be ok to run them?
I even have a Trek Madone that they say takes 28s but when I put a 28mm GP4000 on I am not satisfied with the clearance, so I don't use that tyre.
Surely it is ultimately up to the user/operator to make sure they are happy with the clearance on whatever combo they are using?

JoeO

The bike came spec-ed with 25 mm tires. I'm going to go out on a limb here and guess that maybe it was designed for them.

Dean V

The same wheels and tyres that you were using?

JoeO

The spec-ed wheels were wider. Smart Enve SES 3.4, the pre-2017 versions which were, as I recall 24.5-ish mm wide at the brake track. I don't remember the brand of tires I think it was Schwalbe but I'm not sure. But they were 25 mm.

Now you are going to try to tell me that I made an error because I switched tire brands?

cpach

Huh, have 26mm Bontrager R3 TLRs on 19.5mm internal rims on my 2011 Supersix. I think clearance to the FD clamp is a little over a millimeter, but otherwise it's all fine. Also ran GP4000s on 14mm internal rims before. Did they redesign the frame with even tighter clearance after my bike?

goenrdoug

While there is nothing that specifically states what size tires/rims are usable (and, really, with the differences in how tires from different brands actually inflate, how could they state anything definitively) page 49 of the Supersix Evo users manual says:

It's the whole reason we have this thread.

Congrats on getting a new frame out of Cannondale despite knowing that your frame has limitations, but can those of us who still have one of these frames (including YOU!) get back to the subject of "what wheelset(s) can I legitimately use for my bike without endangering my frame/life?"

mugoftea

I own a Supersix Evo 2013. I'm using 25mm Conti GP4000SII's mounted on Mavic Ksyrium SLE's and have plenty of room around the front fork, seat stays & chain stays. I've also ran some 25mm Vittoria Corsa G+ graphenes on the same wheels which seemed to give a little more clearance.

JoeO

Fortunately for me, there was nothing special or oversized about the 25mm Conti tires I used. The Cannondale rep agreed. He actually saw the bike in person, with the tires and wheels on it. Having googled accounts of their history on this topic, I was not optimistic. Yet, despite having a vested interest in not replacing it, and despite the company's history of not doing so, he took one look at my bike and handed over a brand-new, top-of-the-line Black Inc Nano frameset. No questions asked. So I'm fine with the spirit of the law as well as the letter.

To get back to the width of wheels, I just picked up a brand new digital caliper and measured the chainstays. The narrowest point of the chainstays up to the edge of the wheel brake track on my replacement Nano measures 32.5 mm. So 25 mm wheels would have about 3.75 mm of play on either side. I'm not sure if that's enough

Regardless if I were to find an aero wheel that I felt were narrow enough, it would still complicate matters. Tires inflate wider as rim width gets wider. So while 25 mm tire might be OK on a very stiff 20 mm rim, I doubt there is any wheel stiff enough to make it acceptable on a 24-25 mm rim. With wheels that wide, I'd definitely have to go a tire size down, no matter how they originally spec-ed this particular one.

goenrdoug

Not necessarily. Think of it as an air volume thing. If the rim is wider, more of the air volume is low in the tire space between the rim edges and less has to be up in the bulbous light-bulb shaped area of the rubber.


This is why a wide rim and an appropriately wider tire end up being more aero -- because it's less light-bulb shaped and more smooth transition from the tire to the rim. As such, you can get the same air (and pressure) without having quite as wide of a tire area to potentially rub on the chainstays.

That's why it would be ideal to figure out exactly how wide of a rim we could put on these bikes and end up with a minimally deformed tire.

JoeO

I yield to your understanding on the physics of it. I yield to just about anybody on the physics of it - not my area. But I've certainly read of tests that found what I described. My local bike mech was mentioning it just the other day. Certainly I'll have to be wary of it. But I'm willing to risk it that just about any modern deep wheel would likely be far more aero than my 20.8 (external) mm box-rim-ish C24s with 25 mm tires hanging out over the edges.

In the end, I suspect I'm going to just have to suck it up, take a chance, and buy some wider wheels and then see how much wider the tire gets. Nobody I know has (for me to test) any of the wheels that I'd want to buy.

If a wider wheel make my tire any wider at all, I'll go to 23s. I'm more worried about the how much clearance I need on either side for the wheel

goenrdoug

I only gained any level of understanding of this by reading the posts of much-more-well-informed individuals here on the forum. There have been marathon threads on the subject with many diagrams and whatnot.

Keep us posted on your experience.. My mavics will wear thin at the brake track or something and I'll need to start wheelset shopping, myself, eventually..

JoeO

Epilogue:

After a very long search and countless hours spent obsessing over this over the past two months, I finally opted not to push the envelope and bought a pair of Giant SLR 0 Aero 55s. The external width is 23 mm and the internal width is 17. (Compared to 20.8/15 for my Shimano C24s). I just liked the specs and quality overall. Virtually every other candidate had one thing I didn't like.

The extra internal width made my Conti GP 4000S 25 mm tires sit a bit wider. They still seemed fine just riding up and down my street but as they were a bit closer to the rim, I decided to play it safe and went down one notch to the 23 mm versions.

I already miss that extra 2 mm but I'm still quite happy with the wheels.

But as they don't push the width envelope, I certainly can't tell anyone how wide you can go. Clearly one poster ("FerrariF2002") was able to go as wide as 25.5. But mostly I guess as long as you're within that limit, it's really the internal width that matters. Whey they rub, they rub at the tire, not at the brake track.