Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Continental GP4000S 700x28cc side slashers

Notices
Road Cycling ďIt is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.Ē -- Ernest Hemingway

Continental GP4000S 700x28cc side slashers

Old 06-16-20, 06:20 AM
  #1  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
Continental GP4000S 700x28cc side slashers

This is the second time it happens to me this season.
I go for a ride, has to ride on the shoulder of the road on heavy traffic roads for couple of kms with some gravel rocks on the shoulder and the first time my front tire was slashed on the side of the rolling band. Didnít notice it and the tire blew out when I pumped it to 110 PSI and saw that after I inspected the tire.

now it happened Sunday on the road my rear tire blew out and had to repair it and squeeze a Lezyne boot temporarily to get back home.

never ever had that problem with 25cc and I have been riding those for decades.

is it the 28cc that makes the lateral part of the tire prone to that?


dr_max is offline  
Old 06-16-20, 06:23 AM
  #2  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 30,562

Bikes: R3 Disc, Haanjo

Mentioned: 337 Post(s)
Tagged: 1 Thread(s)
Quoted: 13523 Post(s)
Liked 2,803 Times in 1,507 Posts
Sounds like you were lucky in the past - GP4Ks have a long history of sidewall slashes.
WhyFi is offline  
Likes For WhyFi:
Old 06-16-20, 09:40 AM
  #3  
popeye
Senior Member
 
Join Date: Nov 2004
Location: Newport Beach, CA
Posts: 1,604

Bikes: S works Tarmac, Felt TK2 track

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 196 Post(s)
Likes: 0
Liked 52 Times in 35 Posts
28C 110 lbs? What do you weight? It is the supple sidewalls that make these great riding tires.
popeye is offline  
Likes For popeye:
Old 06-16-20, 10:19 AM
  #4  
Ogsarg
Senior Member
 
Join Date: Feb 2017
Location: Hollister, CA (not the surf town)
Posts: 1,095

Bikes: 2019 Specialized Roubaix Comp Di2, 2009 Roubaix, early 90's Giant Iguana

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 419 Post(s)
Liked 494 Times in 213 Posts
I gave up on the GP4000's for that very reason. Had several sidewall flats and one blowout (lost all pressure in about 2 seconds) from hitting small rocks and general roadside debris. I am trying a GP5000 on my new bike rear and so far so good but only have about 500 miles on it.

Why are you running 110PSI? Unless you are a really big guy, that is way too high.
Ogsarg is online now  
Old 06-16-20, 11:05 AM
  #5  
Elvo
Senior Member
 
Join Date: Oct 2006
Location: Orange County, CA
Posts: 4,414
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 462 Post(s)
Likes: 0
Liked 131 Times in 76 Posts
110 is really high for 28mm
Elvo is offline  
Likes For Elvo:
Old 06-16-20, 11:13 AM
  #6  
sfrider 
Asleep at the bars
 
sfrider's Avatar
 
Join Date: May 2006
Location: San Francisco, CA
Posts: 1,548
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 160 Post(s)
Liked 127 Times in 79 Posts
Definitely not a gravel tire. I do occasionally ride dirt shortcuts or short byways for the scenery, but if it gets rocky I step off and walk it. Fortunately in my case rocks are easily spotted well in advance, and typically easily avoided. But if there's no getting around... I'll walk a few paces. But even then I understand doing this will likely shorten their life span. (This is GP5k though, but I rode 4000s before, and 3000s before that, and they're all the same deal.)
sfrider is offline  
Old 06-16-20, 05:01 PM
  #7  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 993

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 598 Post(s)
Liked 170 Times in 125 Posts
Itís worth noting that higher pressure tires will cut more easily than lower pressure tires.

If you weigh 160-180lbs, try going way, way, way down. Like 75psi. See what happens.
smashndash is offline  
Old 06-16-20, 05:04 PM
  #8  
Tacoenthusiast
Senior Member
 
Join Date: Mar 2020
Posts: 232
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 218 Times in 83 Posts
Originally Posted by Elvo View Post
110 is really high for 28mm
It's really high for 23mm

It's really really really high for 28s
Tacoenthusiast is offline  
Likes For Tacoenthusiast:
Old 06-17-20, 07:23 AM
  #9  
Nachoman
well hello there
 
Nachoman's Avatar
 
Join Date: May 2005
Location: Point Loma, CA
Posts: 15,146

Bikes: Bill Holland (Road-Ti), Fuji Roubaix Pro (back-up), Bike Friday (folder), Co-Motion (tandem) & Trek 750 (hybrid)

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 414 Post(s)
Liked 139 Times in 89 Posts
I stopped buying them for this reason too.
__________________
.
.

Two wheels good. Four wheels bad.
Nachoman is offline  
Old 06-17-20, 07:27 AM
  #10  
mprince
Senior Member
 
Join Date: Sep 2019
Location: Mooresville, NC
Posts: 126

Bikes: Steelman Stage Race, Dura-Ace 9s

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 30 Post(s)
Liked 47 Times in 27 Posts
I have these in 25mm, I am far heavier than you and keep pressures in the 90's, I've ridden them as low as 80-85 with no issues. Mine are fairly new, but no sidewall issues yet, and I have been checking them pretty regularly.
mprince is offline  
Old 06-17-20, 07:34 AM
  #11  
TMonk
Not actually Tmonk
 
TMonk's Avatar
 
Join Date: Jun 2007
Location: San Diego, CA
Posts: 11,601

Bikes: road, track, mtb

Mentioned: 133 Post(s)
Tagged: 0 Thread(s)
Quoted: 1081 Post(s)
Liked 503 Times in 268 Posts
I've had sidewall slashes on a few GP4k's. In all other regards they're a decent tire so I'll buy them and risk it if they're heavily discounted. But otherwise no.
__________________
"Your beauty is an aeroplane;
so high, my heart cannot bear the strain." -A.C. Jobim, Triste
TMonk is offline  
Likes For TMonk:
Old 06-17-20, 03:18 PM
  #12  
MSchott
Senior Member
 
Join Date: Jul 2008
Location: Farmington Hills, MI
Posts: 368

Bikes: 2017 Specialized Roubaix Sport SL4

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 90 Post(s)
Liked 40 Times in 30 Posts
Originally Posted by mprince View Post
I have these in 25mm, I am far heavier than you and keep pressures in the 90's, I've ridden them as low as 80-85 with no issues. Mine are fairly new, but no sidewall issues yet, and I have been checking them pretty regularly.
And Iím 200 pounds and am riding these tires in 23mm width at 80-85 psi with no issues.
MSchott is offline  
Likes For MSchott:
Old 06-17-20, 03:32 PM
  #13  
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 8,630

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 100 Post(s)
Tagged: 0 Thread(s)
Quoted: 2386 Post(s)
Likes: 0
Liked 828 Times in 558 Posts
I ride Vittoria Corsa G+, 25s @ 102psi, 28s @ 92psi. I don't ride gravel anymore (too rough on my too-many-times scrambled brain and when I knew I was going to be riding gravel, switched wheels and tires but if the pavement ends, it would never occur ot me to walk. I have cut the G+ tires, but not often enough to address as a worry.

I'm not a good judge of Continental tires. Other than the ice tires I love (for one weekend a year here in Oregon) I have had nothing but poor experiences on Contis.

Ben
79pmooney is offline  
Old 06-17-20, 03:47 PM
  #14  
BlazingPedals
Senior Member
 
BlazingPedals's Avatar
 
Join Date: Dec 2004
Location: Middle of da Mitten
Posts: 11,553

Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, Catrike Speed

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1166 Post(s)
Liked 244 Times in 171 Posts
Originally Posted by Tacoenthusiast View Post
It's really high for 23mm

It's really really really high for 28s
Depends on rider weight. I run 23s and at 100psi I'll get constant pinch flats, sometimes several on a single ride.
BlazingPedals is offline  
Old 06-17-20, 05:21 PM
  #15  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
I had a snakebite pinch flat once at the end of last season hitting a pothole with my 28cc at 90psi in my rear wheel.

thats the only reason I run them at 110 now,
Iím 170 pounds off racing, 145 pound while racing
dr_max is offline  
Old 06-17-20, 10:11 PM
  #16  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 993

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 598 Post(s)
Liked 170 Times in 125 Posts
Originally Posted by dr_max View Post
I had a snakebite pinch flat once at the end of last season hitting a pothole with my 28cc at 90psi in my rear wheel.

thats the only reason I run them at 110 now,
Iím 170 pounds off racing, 145 pound while racing
You may as well switch to solid rubber tires with that logic. The tires exist to deform to the road. You should go TL if you are that afraid of pinch flats.

I weigh 145lbs at my heaviest and I ran 45-50psi in my 28mm tires, with tubes. I can probably count on one hand how many times Iíve pinched. And some of those were totally brutal hits.

Iím not gonna command you to run lower pressures because everyone is allowed to have their own opinions and youíre not hurting anyone but yourself.

However, youíre not the only person to ever encounter a pothole and perhaps you should consider why the rest of us donít just run the max pressure all the time.
smashndash is offline  
Likes For smashndash:
Old 06-18-20, 02:59 AM
  #17  
Leinster
Senior Member
 
Join Date: Jun 2013
Location: location location
Posts: 2,621

Bikes: MBK Super Mirage 1991, CAAD10, Yuba Mundo Lux, and a Cannondale Criterium Single Speed

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 196 Post(s)
Liked 104 Times in 80 Posts
Originally Posted by MSchott View Post
And Iím 200 pounds and am riding these tires in 23mm width at 80-85 psi with no issues.
Similar here. Iíve taken them off road, hit potholes, no issues. I may be tempting fate here...
Leinster is offline  
Likes For Leinster:
Old 06-18-20, 06:51 AM
  #18  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
Originally Posted by smashndash View Post
You may as well switch to solid rubber tires with that logic. The tires exist to deform to the road. You should go TL if you are that afraid of pinch flats.

I weigh 145lbs at my heaviest and I ran 45-50psi in my 28mm tires, with tubes. I can probably count on one hand how many times Iíve pinched. And some of those were totally brutal hits.

Iím not gonna command you to run lower pressures because everyone is allowed to have their own opinions and youíre not hurting anyone but yourself.

However, youíre not the only person to ever encounter a pothole and perhaps you should consider why the rest of us donít just run the max pressure all the time.
have you read studies on the lowest rolling resistance according to the tire diameter?
I give more weight to that than personal opinions or internet experts.
dr_max is offline  
Old 06-18-20, 06:59 AM
  #19  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 30,562

Bikes: R3 Disc, Haanjo

Mentioned: 337 Post(s)
Tagged: 1 Thread(s)
Quoted: 13523 Post(s)
Liked 2,803 Times in 1,507 Posts
Originally Posted by dr_max View Post
have you read studies on the lowest rolling resistance according to the tire diameter?
I give more weight to that than personal opinions or internet experts.
We have. Have you read studies on suspension losses?
WhyFi is offline  
Old 06-18-20, 11:26 AM
  #20  
billridesbikes
Senior Member
 
Join Date: Nov 2019
Posts: 214
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 67 Post(s)
Liked 122 Times in 72 Posts
Not going to enter the tire psi debate but riding where the road derbies have accumulated only leads to tears and heartache.

Not only is it strewn with trash and debris but gravel can hide sharp road edges or shallow depressions filled with sand and gravel. Drivers treat objects in the gutter of the road, including cyclists and pedestrians, with complete disregard as if they are blind to this part of the road. It’s better to ride out to the left just a bit away from the debris, ideally a few inches to the right of the fog line, even on a very busy road so you have some visibility and don’t risk damaging your tires or sliding out into the road because a gravel patch takes out your front wheel.

If there is no way to avoid riding in the gutter then switch a tire that can take this kind of abuse like Gatorskins, and save the lightweight tires for race day or events.
billridesbikes is offline  
Likes For billridesbikes:
Old 06-18-20, 12:37 PM
  #21  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
Originally Posted by WhyFi View Post
We have. Have you read studies on suspension losses?
ď

Tyre pressure and rolling resistance

ďIt is true that the higher the inflation pressure, the lower the rolling resistance of the tyre,Ē Schwalbe UKís Dave Taylor says. ďItís also worth pointing out that a tyreís 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.ĒĒ
dr_max is offline  
Old 06-18-20, 12:44 PM
  #22  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
Originally Posted by billridesbikes View Post
Not going to enter the tire psi debate but riding where the road derbies have accumulated only leads to tears and heartache.

Not only is it strewn with trash and debris but gravel can hide sharp road edges or shallow depressions filled with sand and gravel. Drivers treat objects in the gutter of the road, including cyclists and pedestrians, with complete disregard as if they are blind to this part of the road. Itís better to ride out to the left just a bit away from the debris, ideally a few inches to the right of the fog line, even on a very busy road so you have some visibility and donít risk damaging your tires or sliding out into the road because a gravel patch takes out your front wheel.

If there is no way to avoid riding in the gutter then switch a tire that can take this kind of abuse like Gatorskins, and save the lightweight tires for race day or events.
ďďIf you have great road conditions and you would like to ride very fast ó in a race, for example ó inflate to the maximum permitted pressure. Using the example of a 25c tyre, you can reduce rolling resistance by around 10 per cent simply by using 8.5 bar [123psi] instead of 6.5 bar [94psi].ĒĒ

itís not even a debate
dr_max is offline  
Old 06-18-20, 12:48 PM
  #23  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 993

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 598 Post(s)
Liked 170 Times in 125 Posts
Originally Posted by dr_max View Post
ď

Tyre pressure and rolling resistance

ďIt is true that the higher the inflation pressure, the lower the rolling resistance of the tyre,Ē Schwalbe UKís Dave Taylor says. ďItís also worth pointing out that a tyreís 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.ĒĒ
Again, you should ask yourself why we donít ride on solid rubber or rubber coated steel tires. A steel tire would easily record fewer losses than even a TT tire pumped up to 150 psi. But we donít use them.

Your excessive sidewall cuts are a) to be expected from the gp 4k but also b) to be expected from a tire run at excessive pressure.

https://www.cxmagazine.com/gravel-ti...all-protection
smashndash is offline  
Old 06-18-20, 12:52 PM
  #24  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
Originally Posted by smashndash View Post
Again, you should ask yourself why we donít ride on solid rubber or rubber coated steel tires. A steel tire would easily record fewer losses than even a TT tire pumped up to 150 psi. But we donít use them.

Your excessive sidewall cuts are a) to be expected from the gp 4k but also b) to be expected from a tire run at excessive pressure.

https://www.cxmagazine.com/gravel-ti...all-protection
lower pressure is worse, it is exposing more sidewalls to the cuts.
as stated in your article

ďďlower 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.Ē
Brown did add that ď[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,Ē before making sure to note that Maxxisí ďMud Wrestler CX tire also has EXO sidewalls since you never know what youíll run into in a deep enough mud-hole.Ē Interesting, and a good note of caution.Ē
dr_max is offline  
Old 06-18-20, 12:58 PM
  #25  
dr_max
Senior Member
Thread Starter
 
dr_max's Avatar
 
Join Date: Feb 2008
Location: Montreal
Posts: 378

Bikes: BMC SLC01 Promachine with full DA grupo on Ksyrium ES/ BMC Roadmachine 01 One disc Ultegra with DT Swiss

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Liked 45 Times in 27 Posts
Originally Posted by smashndash View Post
Again, you should ask yourself why we donít ride on solid rubber or rubber coated steel tires. A steel tire would easily record fewer losses than even a TT tire pumped up to 150 psi. But we donít use them.

Your excessive sidewall cuts are a) to be expected from the gp 4k but also b) to be expected from a tire run at excessive pressure.

https://www.cxmagazine.com/gravel-ti...all-protection
land the reason we donít ride in solid rubber or steel tires is for optimal weight/resistance scenario which is best in inflated tires with lower inertia to accelerate and climb hills with a trade off being prone to puncture.

same reason they use carbon frames, the stiffest for the weight, even if they are not the most durable or stiff.

some people would prefer riding stainless steel frames with steel wheels at 15kph and never change parts.
come people would prefer riding carbon frames with rubber inflated tires and change tires during the season.
dr_max is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.