Brompton are now supplying their own Schwalbe Kojak tyre – with a reflective sidewall for added visibility to cars.

- Andrew

Microknobs: to be honest, the effect is rather small. The compound is far, far more important. That is also the reason that our top performance tires like Ultremo are pure slicks.

Sean, I guess I’ll rewrite that paragraph you were referring to (“The Stelvio featured a micro-tread pattern on the sides for better grip when cornering.”)

As your reaction confirms, the sentence is ambiguous and can be interpreted as undue emphasis on tire texture, while it’s the rubber that counts. Stelvio had 2 different rubber mixtures: a hard wearing compound at the center, a grippier silica mix at the sides.

As to “racing tires”: if we’re talking rolling resistance, I wonder if going narrower and higher pressure will really help or hurt. It appears that the Scorcher, while a good 40mm wide, also has quite low rolling resistance (see http://www.greenspeed.com.au/scorcher.html ).

I’m not talking exclusively rolling resistance. Yes, rolling resistance is an important factor, but another one is the size of the inflated tire. As I feel it, the lower the volume of the flexible tire, the more direct is the contact with the road. The rim moves less relative to the tire road contact area when cornering or accelerating. More precision and system feedback, but less shock absorption.

At 280 grams it’s obviously heavier than the Kojak, but…
My interest in the Scorcher is really because I’m looking for a comfier tire: but if it’s more efficient too, that sounds good to me.

Ah! Well, if comfort is a priority, then I guess the Scorcher might be good.

Personally, I’m not looking for comfort. I mean, for me, a road / racing bike is pretty comfy these days, when built with a nice stiffness / resiliency ratio, fitted properly, including a corresponding saddle (Fizik Aliante Gamma / Vitesse for my sitbones).

So, I can’t share in-depth information on how comfortable a tire is. Kojak is more comfy than Stelvio, underinflated is comfier, but that’s about it. Just not something I’ve looked for and tested myself.

As to “racing tires”: if we’re talking rolling resistance, I wonder if going narrower and higher pressure will really help or hurt. It appears that the Scorcher, while a good 40mm wide, also has quite low rolling resistance (see http://www.greenspeed.com.au/scorcher.html ). At 280 grams it’s obviously heavier than the Kojak, but…

My interest in the Scorcher is really because I’m looking for a comfier tire: but if it’s more efficient too, that sounds good to me.

Thanks for the comment.

1. Sheldon Brown was quite insistant that tread, and particularly microtread, was entirely cosmetic; and in no way did it contribute to better grip on a road. Quite to the contrary, tread lowered the total amount of rubber hitting the road and thus made the tire *less* grippy.

I agree with Sheldon. I do prefer slick, bald tires. Have been riding slicks (sometimes semi-slicks for off-asphalt) all my life, since childhood, with a few knobby exceptions.

Should I improve some parts of my article?

I thought I was clear I preferred the classic slick, when saying “Maybe a Primo Comet, but it’s 37 mm (1.46 in) wide, rated at 85 psi and has a micro-tread all over“.

The Stelvios were perfectly slick on the rolling side. The micro-tread, or, to be precise, not a micro-tread, but some kind of rectangular pattern, was on the sides, coming in contact with the road only when leaning the bike while cornering.

I’m unsure whether this pattern is purely cosmetic or not, all I can say is that it worked really great.

2. The Kojak has a slick competitor in 349: the Greenspeed Scorcher. Which is comfier? Which has lower rolling resistance?

I disagree. The Greenspeed Scorcher is 16 x 1.5 in / ETRTO 40-349, that is, it’s 40 mm wide! Which, at least on the Brompton, is starting to be a bit tight, clearance-wise. It’s even wider than the burly Schwalbe Marathon Plus. I’d say it’s more of a ballon-bike tire than a narrow-slick-racing tire. So I wasn’t thinking about testing it.

I can only guess that it works good for Greenspeed’s trikes, because they don’t lean when cornering. Nothing substantiated by my experience, though.

What do you think?

2. The Kojak has a slick competitor in 349: the Greenspeed Scorcher. Which is comfier? Which has lower rolling resistance?

3. Sad that the Kojak appears not to have reflective sidewalls.