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Continental GP4000S 700x28cc side slashers

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Continental GP4000S 700x28cc side slashers

Old 06-18-20, 02:21 PM
  #26  
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Originally Posted by dr_max View Post

Tyre pressure and rolling resistance

“It is true that the higher the inflation pressure, the lower the rolling resistance of the tyre,” Schwalbe UK’s Dave Taylor says. “It’s also worth pointing out that a tyre’s susceptibility to punctures is lower with high pressures, too. And if the inflation pressure is continuously too low, premature tyre wear is the result, which usually means cracking of the sidewall and unnecessarily high abrasion.””
So that's a "no"?
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Old 06-18-20, 03:19 PM
  #27  
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Originally Posted by dr_max View Post
lower pressure is worse, it is exposing more sidewalls to the cuts.
as stated in your article

““lower pressures expose more sidewall to cuts. Trends towards wider rims are exposing more tire sidewalls to rocks too, sometimes before the sideknobs would hit. This is a big reason why our gravel tires either have sidewall protection via EXO inserts or bead-to-bead protection via our Silkshield breaker.”
Brown did add that “[l]ower pressures may [also] bottom out on the rim, pinch flatting the tube or tire casing, but higher pressures do not add protection against cuts. Lower pressures will, however, expose more of the sidewall to gravel by flattening out the tread,” before making sure to note that Maxxis’ “Mud Wrestler CX tire also has EXO sidewalls since you never know what you’ll run into in a deep enough mud-hole.” Interesting, and a good note of caution.”
This is correct, IME. Lower pressure is worse for road damage. That said, 110 on 28s is a bit nuts. I think the OP is talking about 28mm 4KIIs tires, which are actually almost 32mm on my 23mm outside rims, so that's really nuts. I run 95 with those tires on our tandem, 285 lb. team, 40 lb bike, never a pinch flat. I've actually had very good experiences with those tires, very very few sidewall cuts.

If riding on smooth asphalt, not chipseal, higher pressure is faster, up to some point which might be below 110 in 31-32mm tires. However, I never, ever, ride in the debris field. Too dangerous for one thing, and then there's all the tire damage. I mostly ride on shoulderless country roads and ride a few inches to the left of the fog line. If there's over a foot of pavement to the right of the fog line and it's clean, I'll ride to the right of the line, but usually that extra bit on the right disappears here and there, which makes one swerve. Better to ride to the left and hold your line. It's always safest to hold your line.

The big pisser is rumble strips, because then the shoulder to the right is almost always full of debris, in which case I have to ride to the left of the rumble strip. Which I hate, so I try to avoid those roads. Or maybe some of you live where they actually sweep the shoulders. I don't.
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Old 06-19-20, 05:48 AM
  #28  
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Originally Posted by Carbonfiberboy View Post
This is correct, IME. Lower pressure is worse for road damage. That said, 110 on 28s is a bit nuts. I think the OP is talking about 28mm 4KIIs tires, which are actually almost 32mm on my 23mm outside rims, so that's really nuts. I run 95 with those tires on our tandem, 285 lb. team, 40 lb bike, never a pinch flat. I've actually had very good experiences with those tires, very very few sidewall cuts.

If riding on smooth asphalt, not chipseal, higher pressure is faster, up to some point which might be below 110 in 31-32mm tires. However, I never, ever, ride in the debris field. Too dangerous for one thing, and then there's all the tire damage. I mostly ride on shoulderless country roads and ride a few inches to the left of the fog line. If there's over a foot of pavement to the right of the fog line and it's clean, I'll ride to the right of the line, but usually that extra bit on the right disappears here and there, which makes one swerve. Better to ride to the left and hold your line. It's always safest to hold your line.

The big pisser is rumble strips, because then the shoulder to the right is almost always full of debris, in which case I have to ride to the left of the rumble strip. Which I hate, so I try to avoid those roads. Or maybe some of you live where they actually sweep the shoulders. I don't.
my 110 km countryside ride has 98% of nice brand new road, I usually pump 90 to 100 psi for maximum efficiency because one of the girl I ride with is making all the QOMs on every segment. However there is a road between 2 segments which has destroyed shoulder and the rocks are where the white line is and there is a lot of trucks on both side on a single lane road and they can’t move and don’t move when passing you. Either you get killed by not moving or ride where some gravel is and get your tires slashed. Never happened to my 23cc and 25cc Continentals at 120 PSI over 16 years of riding there. That’s why I was wondering if 28cc were more prone to sidewall slashing at lower pressure
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Old 06-19-20, 06:04 AM
  #29  
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I've been pretty happy with these in 25, you may prefer 28s.

These will give you a little more durability without going all the way to Gatorskins.
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Old 06-19-20, 06:17 AM
  #30  
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Originally Posted by shelbyfv View Post
I've been pretty happy with these in 25, you may prefer 28s.

These will give you a little more durability without going all the way to Gatorskins.
Wow are those new? Thanks for bringing these to my attention!
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Old 06-19-20, 06:20 AM
  #31  
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I've been using them for several years. I went from GP4000s and couldn't tell a difference in ride. Don't know how they compare to the newer 5000s.
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Old 06-19-20, 11:27 AM
  #32  
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Originally Posted by dr_max View Post
my 110 km countryside ride has 98% of nice brand new road, I usually pump 90 to 100 psi for maximum efficiency because one of the girl I ride with is making all the QOMs on every segment. However there is a road between 2 segments which has destroyed shoulder and the rocks are where the white line is and there is a lot of trucks on both side on a single lane road and they can’t move and don’t move when passing you. Either you get killed by not moving or ride where some gravel is and get your tires slashed. Never happened to my 23cc and 25cc Continentals at 120 PSI over 16 years of riding there. That’s why I was wondering if 28cc were more prone to sidewall slashing at lower pressure
Oh man. There's a road just like that near me that was one of my favorite roads, until they put in a gravel pit off it and a big equipment yard. I've never ridden there again, and my serious advice is don't you ride there either. That combo of road and traffic really increases the odds of uh, you know.

The 4000IIs tires are much wider in 28mm so that makes them more likely to hit stuff. The 5000 tires really are 28mm inflated. Both have thin sidewalls, but in that stuff, even bead to bead protection is going to see sidewall damage, just not resulting in as many flats. But you know, you look at at a tire, see cord on the sidewall, wonder if you should take the tire off.
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Old 06-19-20, 01:31 PM
  #33  
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I run 25mm 4000s at like 115 PSI and 110 PSI and love it. I tried going down, and a little is ok, but like 100 and 95 is just too low. Tires need to be hard.
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Old 06-19-20, 01:37 PM
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Interesting stories. I’m 170 lbs. and I rode 3 tires Continental GP S2 (23 mm) on rear wheel for a total of 30.000 km. Pressure around 100 PSI, on roads with little below average quality (I think). I had only one puncture and no pitch or sidewall issues.

Am I a lucky man?
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Old 06-19-20, 08:09 PM
  #35  
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Originally Posted by Redbullet View Post
Interesting stories. I’m 170 lbs. and I rode 3 tires Continental GP S2 (23 mm) on rear wheel for a total of 30.000 km. Pressure around 100 PSI, on roads with little below average quality (I think). I had only one puncture and no pitch or sidewall issues.

Am I a lucky man?
I rode Michelin ProRace2 for like 5 years,
then went to pro race 3, started noticing they worn faster and had multiple flats with ProRace4

switched to continental 7 years ago, never had any flat with the 23cc tires ever, used the same pair for 2 seasons had almost 10k kms on them, then Inread à study that 25cc had less road contact and absorbed bad tarmac vibrations better. Switched to 25cc and had 2 or 3 punctures from sidewalls.

2 years ago I switched to 28cc with my new BMC Roadmachine 01 One with disc brakes and had 2 sidewalls blowout from the tube herniating through the defect, even made a crazy descent with a partially herniated tube on the front tire without knowing before it blew out when I pumped to 100psi.

I used to go downhill at over 100kph on some descends I knew well but cant do that anymore with what I know from their sidewall fragility.

Today, just had a sidewall puncture on a new pair of Continental GP4000s I had left in stock. Changed the tire on a passing road with a lot of 18 wheelers passing fast and burning under then hot sun at 38 degrees Celsius. Will try the 28cc 5000 but will search something with better sidewall protection as the roads are getting crowdy since I can’t ride in Vermont from the borders being closed because of COVID19.
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