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Old 11-04-12, 02:52 PM   #1
chagzuki
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Kojaks - opinions

I recently installed a folding bead Kojak on my Brompton front wheel. Whilst putting it on I couldn't help but be amazed by how elastic the side walls are and I figured that despite the lower volume of air the tyre might prove to be just as comfortable as larger volume ones. However, for the time being I can't really assess the tyre as I'm using a Pantour hub which is soaking up bumps very efficiently.

I'm considering putting one on the rear and thought I'd fish for opinions before deciding whether or not to do so.
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Old 11-04-12, 10:29 PM   #2
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I loved the way they rode on my Brompton and I got lots of flats with them. I eventually went back to the green label Brompton brand tires. If I didn't have thorns to contend with I would still be using the Kojaks. Such a nice ride.
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Old 11-04-12, 10:32 PM   #3
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Originally Posted by chagzuki View Post
I recently installed a folding bead Kojak on my Brompton front wheel. Whilst putting it on I couldn't help but be amazed by how elastic the side walls are and I figured that despite the lower volume of air the tyre might prove to be just as comfortable as larger volume ones. However, for the time being I can't really assess the tyre as I'm using a Pantour hub which is soaking up bumps very efficiently.

I'm considering putting one on the rear and thought I'd fish for opinions before deciding whether or not to do so.
We have 1.35" Kojacks on both our custom Fridays. They more comfortable and faster than the stock 1.50" Marathons, IMO.

Lou
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Old 11-05-12, 12:58 AM   #4
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I wonder what the relative contribution of tyre construction is to rider comfort... I am just thinking of 50kg or so on the rear tyre, with the air holding the wheel up with say 80psi, about just how much a sidewall matters in this scenario...? I suspect very little. So if I think back on tyres I have had on my various bikes, the only one that really sucked was a Marathon Plus, it wallowed terribly unless pumper very hard. But as for the others... I had a Kojak, followed by a Scorcher, and now a Primo on my Brommie back wheel. IfI am brutally honest, then I will admit I can't feel a difference. Even the fatter Scorcher didn't feel particularly different.

(I got very few miles out of the scorcher due to my Zefal tyre liner cutting the tyre casing threads. Slime liners rule.)
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Old 11-05-12, 02:54 AM   #5
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Like my Kojacks, much smoother than marthans due to tread pattern. Not had many flats with them. About 3 in 3 years. Carefull in the wet and loose stuff!
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Old 11-05-12, 05:14 AM   #6
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Jur, in switching tyres did you notice any change in the folded geometry of the Brompton? I don't suppose it would make any practical difference to most people whether the front wheel drops slightly lower due to the rear tyre allowing the main frame to fold a fraction further etc., or vice versa . . it might to me though with the way I have my 5 speed IGH arranged.
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Old 11-05-12, 11:43 AM   #7
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I'm wondering if the rolling resistance of Kojaks ought to be higher than Comets or Scorchers due to the form factor? I.e. fatter tyres deform less . . . with Comets weighing only a shade more perhaps thinking Kojaks = speed is a mistake?
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Old 11-05-12, 03:35 PM   #8
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Originally Posted by chagzuki View Post
However, for the time being I can't really assess the tyre as I'm using a Pantour hub which is soaking up bumps very efficiently.

I'm considering putting one on the rear and thought I'd fish for opinions before deciding whether or not to do so.
Can you swap tires front to rear to see how you like the kojak in back with whatever else on the front Pantour wheel?

Quote:
Originally Posted by jur View Post
I wonder what the relative contribution of tyre construction is to rider comfort... I am just thinking of 50kg or so on the rear tyre, with the air holding the wheel up with say 80psi, about just how much a sidewall matters in this scenario...? I suspect very little. So if I think back on tyres I have had on my various bikes, the only one that really sucked was a Marathon Plus, it wallowed terribly unless pumper very hard. But as for the others... I had a Kojak, followed by a Scorcher, and now a Primo on my Brommie back wheel. IfI am brutally honest, then I will admit I can't feel a difference. Even the fatter Scorcher didn't feel particularly different.
With no way to really measure, I guess it`s one of those judgement calls, but I definitely feel a difference between stiff and soft sidewalls. Never used Kojaks, but I`ve ridden a lot on Paselas and a bit now on Primo Comets, and much prefer the ride to stiff tires- in my case, the stiffest have been studded Marathon Winters (brutal!) folowed by Maxxis Overdrives (rough). Unfortunately, I get a lot more flats with Paselas than with tougher tires. Haven`t flatted my Primos yet, which might either be because they aren`t so prone to it or just good luck, as I have less than 1000 miles on them.

Last edited by rodar y rodar; 11-05-12 at 03:38 PM.
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Old 11-05-12, 04:48 PM   #9
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Jur, in switching tyres did you notice any change in the folded geometry of the Brompton? I don't suppose it would make any practical difference to most people whether the front wheel drops slightly lower due to the rear tyre allowing the main frame to fold a fraction further etc., or vice versa . . it might to me though with the way I have my 5 speed IGH arranged.
The Scorcher was bad for geometry. The wheel pressed in hard on the bottom bracket shell when folded (I added helicopter tape for its protection) and against the top tube. The front wheel was much further from ground, so it would not stand at all. The Primo Comet is much better, does not touch the BB shell and the bike can still stand although it still has to lean over a bit and is a bit precarious.
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Old 11-05-12, 05:17 PM   #10
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Wow, I'm getting a bit nostalgic for the Primo Comets. Legend has it that Vision, the recumbent maker (long gone), enlisted Cheng Shin to help develop this tire, and suddenly, we had a wonderful tire with flexible sidewalls that actually made riding a folding bike fun and enjoyable instead of brutal. There are still many devotees of the Comet. My experiences with them are somewhat limited, running a hodgepodge of tires on all my folders, but I generally liked them. Sometimes not very grippy in the wet with the relative lack of tread, but an overall fine tire.

Don
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Old 11-05-12, 06:07 PM   #11
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Kojaks look bad assed.
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Old 11-05-12, 06:13 PM   #12
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are kojaks similar to stelvios? anyone have experience with both?
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Old 11-06-12, 02:13 AM   #13
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are kojaks similar to stelvios? anyone have experience with both?
Stelvio no longer availalbe 16" ?
Ride very harshly, punture very easily. get damaged easily, and are very difficult to fit.
Kojacks ride smoothly and quickly,( as quick?),but seem to cushion out bumps that rattle with stelvios even with 100+ psi, and can be pretty durable.
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Old 11-06-12, 09:11 AM   #14
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ugh that sucks.. i just bought a pair of stelvios..
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Old 11-08-12, 05:17 PM   #15
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I too find the Kojaks to have a smoother-than-expected ride, even at 95 PSI front and rear. The steel-beaded versions are an especially good bargain, I think.

I've gotten two flats in almost two years.

I will buy when these are worn out.

-Warr
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Old 11-09-12, 11:34 AM   #16
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I tried Kojacs when I wore out my Stelvios. They rode a little better with slightly more rolling resistance--really not really noticeable. I removed the Kojacs since I was getting deep cuts in the tires and did not trust them. Finally fitted Duranos which are theoretically the replacement for the Stelvio. They are very close to the Stelvio with better cut resistance along with better rolling resistance than the Kojac.
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Old 11-11-12, 01:40 AM   #17
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I have been commuting almost daily on a pair of Kojaks for more than a year, and I have been happy with them. I keep them at 110 psi, the suspension on my Birdy folder keeps the ride smooth. The tires are showing some cuts and cracks, but I have had only one puncture since I installed them. I will be replacing them shortly, as they are nearly worn through. I wanted to fit a new set of Panasonic Minits, but I love the durability and long life I have gotten from my Kojaks.
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Old 11-19-12, 03:57 PM   #18
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have kojaks on my speed tr and like it better than the stock big apple. ride is smooth and faster than stock tires. i set the pressure at 100psi. i like the feel of the tiny stones when i am riding on it...
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Old 11-20-12, 02:47 AM   #19
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Just put on a pair of Kojak on my Curve, I like it better than the previous tires (Marathon Original). Not really much of a difference with comfort, only faster. I pumped them to 100psi.

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Old 11-20-12, 04:50 AM   #20
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Just put on a pair of Kojak on my Curve, I like it better than the previous tires (Marathon Original). Not really much of a difference with comfort, only faster. I pumped them to 100psi.

Can i just pouint out the elephat in the room.

Slick tyres are grippy in dry but not in the wet or loose, just in case someone wants kojacks on a commuter bike remember winter. This is the reason I run two Mezzos, one with kojacks and one with marathons.
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Old 11-20-12, 05:59 AM   #21
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Can i just pouint out the elephat in the room.

Slick tyres are grippy in dry but not in the wet or loose, just in case someone wants kojacks on a commuter bike remember winter. This is the reason I run two Mezzos, one with kojacks and one with marathons.
You are so right, last night it was raining, I had to put more attention to the road, lost a bit of traction on some road surface.. kinda scary really.
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Old 11-20-12, 08:58 AM   #22
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profile on the tire is a lot of marketing hype... SUre in deep snow, sand or mud ... it will help to get you trough it.... but remember that your contact point is the size of a quarter... ( very large penny for our Int friends)
the rubber compound, different layers of construction, make much more difference....

I sometimes wonder if somebody who says it was slippery in the rain on Kojaks ( or other slick tires) would have had the same slippery feeling on a different tire .....of course its hard to do... switching tires and ride exacly the same spot, same speed, same angle ..

just sayin ..... maybe cause I love the Kojaks so much ..... the Supremes are my next choice ...:-)

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Old 11-26-12, 06:23 PM   #23
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Can i just pouint out the elephat in the room.

Slick tyres are grippy in dry but not in the wet or loose, just in case someone wants kojacks on a commuter bike remember winter. This is the reason I run two Mezzos, one with kojacks and one with marathons.
While I agree while riding on the loose stuff, it is simply not true that treadless tires like Kojaks fare any worse on wet pavement than treaded tires.

Tread exists on tires for two main reasons: to "bite" into soft surfaces (like dirt, gravel, snow, soft ice, etc.) and to prevent hydroplaning by giving standing water a path to "get out of the way" of the tire's contact patch.

When riding on wet pavement, even with standing water, bicycle tires are too thin and curved to hydroplane, which is rather unlike like a treadless car tire, so there's one "benefit" gone. Pavement also doesn't give, so there's nothing for tread blocks to "bite" into, so there's another one gone.

Then factor in that pavement is never glass-smooth; it is always irregular and therefore has both spaces for water to "get out of the way" through, and the irregularities act like tread "biting" into the smooth surface of the treadless tire, providing more grip than it would on a treaded tire because there's more surface area for the "tread" of the pavement to "bite" into.

Now riding over wet metal plates and wet painted road stripes is very tricky on treadless tires, but it also is on treaded tires; both are slicker-than-snot and hazardous regardless of your tire.

I've been riding on "slick" treadless tires since they became popular in the late 80's in all sorts of weather. I commute rain-or-shine on Kojaks on my folder. There is nothing to the myth that "slick" tires are not suited to wet weather if you limit your riding to paved surfaces.

-Warr
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Old 11-26-12, 06:27 PM   #24
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my primo comets agree wholeheartedly with your well-worded defense of slick tires..
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Old 11-26-12, 07:30 PM   #25
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... When riding on wet pavement, even with standing water, bicycle tires are too thin and curved to hydroplane,..
Not to mention that the speeds at which most people ride a bike is too slow to induce hydroplaning. Rubber compound and carcass construction are more important concerning traction.
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