Tire width vs. height

[mhespenheide]

Hi, all.

On the strength of the recommendations of some forum members, I recently picked up a CAAD 10 because some of them appear to have gobs more tire clearance than most race bikes -- like, clearance for 700c x 30mm. Blinded by the possibilities of a fast-riding road bike with cushy tires but without the custom cost or lead times, I pulled the trigger. I'm an idiot, though, because I bought it used and didn't check the clearance beforehand...

On this particular frame, it looks like there's plenty of room for wider tires, but the brake bridge is too low. A 700c x 28mm Continental GP4000 on a wide rim hits the brake bridge, even though there's 2-3mm on each side.

Are there any tires that (magically?) get wider without getting taller? It would seem like physics would demand that tires would approximate the same arcs as the air pressure pushes out evenly...

I could sell the Cannondale without really any loss; I got a good deal on it. But I'd like to use it, if possible.

Alternately, should I head down the rabbit hole of 650b or 650a rims and tires?

Thanks for any thoughts.

[Ken Robb]

on my open pro rims Rivendell Roly-Poly and Ruffy-Tuffy tires are quite round while Paselas are relatively tall and narrow in similar sizes.

[ceolwulf]

Could it possibly work to use 25s on a wide rim to get the width and volume without the height? I'm curious myself about this.

[bironi]

My experience too shows that the height is the number that over-rides the width. The two match on some tires, but don't on many.

[choke]

That's always a guessing game and wide rims can confuse the issue. For example, I had a a pair Ruffy Tuffys mounted on Neutrons. They would clear the back caliper..not great, but it was enough that I felt comfortable riding with them. I then mounted them on A23s and they rubbed the caliper.

On the same bike:
Open Corsa SC 23s on A23s measured around 26mm and had lots of clearance.
Clement Strada on A23s measure 28mm and are close but still clear.
I would guess that the 25 version of the SC would be wider and still have loads of clearance but I haven't tried them.

On another bike I have Pasela 28s. They're on 'normal' width rims and measure about 26mm. They have more clearance than the Ruffy Tuffys had when they were on there.

[thorpej]

Are there any tires that (magically?) get wider without getting taller? It would seem like physics would demand that tires would approximate the same arcs as the air pressure pushes out evenly...

Maxxis has a road tire with a radial casing, which has a lower profile than the standard bias-ply casing. I'm not sure they make it any wider than 23mm, though.

That said, I have a CAAD9, which has similar tire-clearance constraints as the CAAD10. My cushy-tire-of-choice is the 25mm Veloflex Corsa. They're like riding on pillows (I'm 6'4" 185lbs and I ride them at 85-90 rear / 80-85 front on garden-variety DT RR465 rims).

You might be able to fit a 26mm tire like the Grand Bois Cerf blue in there, too... that's another exceptionally comfortable narrow tire.

[Davist]

Wow, that's surprising, I've been running both Continental 4 seasons and Schwalbe ultremos in 28s on both narrow and wide rims on mine with no problems.. I guess that it could be manufacturing tolerances?

[jr59]

I'm pretty sure that not all brakes give you the same clearance. I know that my Campy brakes don't give as much as my DA brake set. I have read somewhere that scram red offers more, but I can not say that for sure.

[Mark McM]

... but only on the inside of the casing.

As you have guessed, the uniform internal air pressure causes the tire casing to assume a nearly perfectly round cross-section, the diameter of that cross-section dependent on the tire casing width and the rim width between sidewalls. However, the external cross-section of the tire is also dependent on the tread thickness. Some treads are very thick near the center, and taper to a thinner depth toward the edges, giving the tire a tall and narrow outer profile when inflated. Other tires have uniform thickness across the entire width of the treads, giving a rounder outer profile.

You may be able to save a few millimeters of space if you use a tire without a bulged tread cross-section.

[Vinci]

You might be able to find a thin-tread tire, like a Conti Supersonic, and get a couple mm back on the height.

You'll probably spend a lot of time next to the road swapping tubes, though.

[bking]

Mine will fit Vitoria rubinos (26.5 actual) but only with ultegra brakes.

[beeatnik]

Veloflex Corsa 25mm on 19mm Kinlin - approx measurement 23

https://farm9.staticflickr.com/8659/15821552507_ef0b02dd60_z.jpg

Challenge Parigi-Roubaix 27mm on 23mm Archetype - approx measurement 30

https://farm8.staticflickr.com/7354/10563747844_8a2e71d58d_c.jpg

Michelin Pro Race 4 25mm on 22mm Velo Orange - aprox measurement 27mm (Conti GP 4 Season 28mm in front)

https://farm6.staticflickr.com/5585/14048958246_a6dc0a13a9_c.jpg

[drsmile]

I got desperate on my travel bike and used the spoke-glued-to-the-dropout trick to gain 3mm of vertical clearance. I have to say that it works amazingly well and I can run 32mm tires on my Breakaway without any noticeable downside.

[Ken Robb]

I got desperate on my travel bike and used the spoke-glued-to-the-dropout trick to gain 3mm of vertical clearance. I have to say that it works amazingly well and I can run 32mm tires on my Breakaway without any noticeable downside.

Pardon my ignorance---HUH?

[PaMtbRider]

I got desperate on my travel bike and used the spoke-glued-to-the-dropout trick to gain 3mm of vertical clearance. I have to say that it works amazingly well and I can run 32mm tires on my Breakaway without any noticeable downside.

If I understand you correctly, accident just waiting to happen. Spoke glued to the dropout to keep the wheel from seating the whole way up in the dropout?

[drsmile]

Pardon my ignorance---HUH?

Basically you cut a spare spoke for 2 pieces the length of the dropout width. Superglue them to the top (facing towards the top of the frame) of the dropout. Check for trueness and clearance with a wheel/tire combo. Once satisfied, Use something like JBWeld to fill in around the spoke pieces. I personally lubed the wheel axle, put the frame upside down, let the JBWeld get to a thick putty consistency, and then inserted the wheel/axle until set. The idea is to make the axle as stable as possible in the new position. It's somewhat analogous to adjustable dropouts, but you have to make sure your dropout is deep enough to still support the axle well in its new position.

Disclaimer: If your wheel falls off while descending at 50mph, I told you not to do this. Hasn't happened to me (yet) but I'm sure it's possible. I pushed and pulled as hard as I could on the wheel to make sure it would stay, plus I definitely won't use lightened or crappy skewers with this setup.

[mhespenheide]

Basically you cut a spare spoke for 2 pieces the length of the dropout width. Superglue them to the top (facing towards the top of the frame) of the dropout. Check for trueness and clearance with a wheel/tire combo. Once satisfied, Use something like JBWeld to fill in around the spoke pieces. I personally lubed the wheel axle, put the frame upside down, let the JBWeld get to a thick putty consistency, and then inserted the wheel/axle until set. The idea is to make the axle as stable as possible in the new position. It's somewhat analogous to adjustable dropouts, but you have to make sure your dropout is deep enough to still support the axle well in its new position.

Disclaimer: If your wheel falls off while descending at 50mph, I told you not to do this. Hasn't happened to me (yet) but I'm sure it's possible. I pushed and pulled as hard as I could on the wheel to make sure it would stay, plus I definitely won't use lightened or crappy skewers with this setup.

Okay; I'm pretty sure I wouldn't do this.

If both sides had replaceable dropouts, I could see machining different dropouts that moved the axle down a few mm, but I think a solid clamping area is a good thing.

[mhespenheide]

Veloflex Corsa 25mm on 19mm Kinlin - approx measurement 23

https://farm9.staticflickr.com/8659/15821552507_ef0b02dd60_z.jpg

Challenge Parigi-Roubaix 27mm on 23mm Archetype - approx measurement 30

https://farm8.staticflickr.com/7354/10563747844_8a2e71d58d_c.jpg


Those are *acres* more clearance than I've got. Either there's a hell of a lot of manufacturing tolerance/slop, or there was a change in the specs from the 2011-2012 run and the 2013-2014 run.