What'r ye runnin' yer Compass Stampede Pass tire pressures at?

[Lungimsam]

Wondering what is the lowest, cushiest, but still safe pressures people are running these tires at?

I don't have much experience with supple 700c tires so wondering.

My only extensive experience on 700c is 120psi 25mm wide Gatorskins and Armadillos.

Don't know what to do with the Rivish 700c tires.

I weigh 170.

Road riding. No loads. I want max cush.

[Brian Campbell]

Running my 38mm Barlow Pass ELs at 45 front, 50 rear. I am 185lbs. Rims are Mavic Open Pros.

[Eric Norris]

I find that below about 50 PSI the tires get “squirmy” when making turns or on a winding road. I weigh about 190 and usually run my Stampede Pass tires at 60-65 PSI. Above that, and the ride quality suffers.

--Eric Norris
campyo...@me.com
www.campyonly.com
campyonlyguy.blogspot.com

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[Deacon Patrick]

I inflate mine to 40psi. I got a pinch flat on rooty/rocky trails my last ride because I didn't inflate them from 10-15psi lower than that. I start to notice squirrelly on fast, curvy descents at 25-30psi.

With abandon,

Patrick

[Ryan Fleming]

I weigh a bit more than you do. 75psi rear and 70psi front; I have the Stampede Pass extralight. I feel I could drop a few pounds (both tire pressure and body weight :) ) however. I think some experimentation is required.

They're very nice supple tires; I think they're nicer riding than the 32..Paselas they replaced 

[Deacon Patrick]

Och! Sorry. I ride Barlow Pass. I'm 200-210 lbs.

[Ron Mc]

210 lbs, running Barlows on my upright at 60psi rear, 40 psi front. 

On my semi-upright, running Stampede at 65psi rear, 55 psi front.  

Mostly concentrate on not shocking the rims and handling.  I have some big hills to go down.  I've also noticed another squishiness that can develop at high speed, when centrifugal forces are stretching tje tire out and they don't have sufficient pressure for good lateral stiffness, but I only see that if I let the pressures drift a little below the numbers above.  

[Tim Gavin]

I'm 220 lbs, and I use 45-50 psi front and 55-60 psi rear in my 38 mm supple tires (Lierre, Pari Moto, et al).  

I start with the "15% tire drop" method, as developed by Frank Berto and further by Jan Heine.  Unfortunately, Berto's charts only went up to 37 mm tires, so you have to extrapolate/experiment with wider tires.  Calculator here.

I'll add 5-10 psi if I'm fully loaded.  I'll drop 5-10 psi if I'm riding more gravel/trail/off-road.

I've found that 38 mm tires feel squirrely to me around 30-35 psi.  

I ran 85 front / 100 rear on my Cerf blue 700 x 26 tires.

I run 60 front / 75 rear on my 700 x 32 Gravel King tires.

I run 30 front / 35 rear on my 26 x 2.1" Thunder Burts.

I run 7 front / 8 rear on my 26 x 4.6" fat bike tires.

[Ryan Fleming]

I have to say I'm still new to Compass tires. My other data point is the 26 X 1.5 McClure Pass tires I'm running on my X0-1 and all-rounder. I feel they're a bit too squishy at around 50psi; I think 60-65 PSI are likely going to turn out to be the sweet spot on these. That being said, they're definitely quality tires

[Mark in Beacon]

I would start with this and then experiment in either direction based on your actual experience on your bike. Rim size may be somewhat of a factor, but don't let a skinny rim keep you from running a plump tire--might just have to add a couple pounds more pressure on the low end. It's not really an exact science. I assume my gauge is somewhat accurate, but I then let the tires go until I think, hey, it's getting a little bouncy. Or squirmy. Or too mushy. Or whatever. I'll pump in some air. Anyway, less is generally more.

[Mark in Beacon]

More specifically, as a data point, on my Stampede-equipped bicycle (and my other 30-32mm tires) I generally pump to about 60 rear, 55 front to start, and let it go down from there. I weigh about 170, and don't carry more that 2-8 pounds on these skinny tire bikes, if that. I suppose 30mm (the measured size of my Stampedes on the current rim) is cushy compared to a 25mm, but I would reserve that adjective for tires 38mm and up. ATMO, of course.

On Tuesday, July 26, 2016 at 1:34:32 PM UTC-4, Lungimsam wrote:

[William deRosset]

Dear Lungimsam,

I am at 11 stone/70 kg, and pump those tires to 4 bar or so, front and rear, and only air them (32-622) up when they get squirmy. It takes a while with butyl tubes.

Best,

Will
William M deRosset
Fort Collins CO

[Tim]

All I know is that I'm typing this response with my left arm in a sling with a separated shoulder from cornering on a downhill with just barely not enough pressure in my Barlow Pass 38mm extra lights. When I rode 23mm tires on my old go fast bikes I was compulsive about keeping my tires rock hard. I love the ride of Compass extra light tires. I started with Stampede Pass on my Hilsen and have since gone to Barlow Pass, with no loss of performance. And I seek out rumble strips on the side of the road just because it is so amazing to float over them. Jan had a post awhile back about running lower pressure so I've been riding as low as I can before the tires get squishy on corners. But usually I check the pressure with a squeeze, only using a gauge on my floor pump when I'm adding air. I think I ride my Stampedes on the Roadeo at around 50psi while I can get by with 35-40 on the Barlows on the AHH. But that crash when my tire squirmed out from under me really sucked!

[Ryan Fleming]

Oh dear, sorry to hear this and hope you heal fast

[Eric Floden]

220 lbs. 60R 55F on my MEC Cote...seems fine with enough front pressure under hard braking and on rough pavement

ef
Vancouver BC

[Steve Palincsar]

The Stampede Pass is a 32mm tire.  You're going to need a good bit more pressure with a tire that narrow than you will for a 38mm tire.

[ascpgh]

I'm 190 and running my SP Els at about 60-65 on Synergy rims when I pump them up, less as the week goes or until they feel too soft. Mostly sidewall squish if I turn sharply low speed or the odd thing or edge in the wheel's path that makes me feel a thud.

Truly remarkable addition to my Rambouillet, Paul Racers facilitating them under fender. I'm going out now for a hot ride to three of the area cemeteries that have very nice monuments. The roads in those are not the smooth asphalt of roads and the terrain is certainly up and down. The Compass tires really are a welcome improvement and benefit to my durability on the bike.

Andy Cheatham

Pittsburgh

On Tuesday, July 26, 2016 at 1:34:32 PM UTC-4, Lungimsam wrote:

[Tony DeFilippo]

45ish front, 60 rear - stampede pass el's on my Bob Jackson... And I'm around 215lbs.

[Scott Henry]

Not a stampede pass, but I run 700x42 cheapo-tubeless at 36psi and I'm about 230#.

On Tue, Jul 26, 2016 at 9:48 PM, Tony DeFilippo <vpi...@gmail.com> wrote:

45ish front, 60 rear - stampede pass el's on my Bob Jackson... And I'm around 215lbs.

[Eric Floden]

oops my bad -- my answer below was for my 700x38s

I run my 700x32 (Stampede Pass) at 70R 65-60F on my Marinoni built Gilles Bertrand road bike

ef

Vancouver

[Lungimsam]

I did 55psi front and rear. Fantastic cush, smoothness,  and speed feeling. But since switched to 28's for better fender clearance. 

[John Hawrylak]

All

The responses provided a wealth of tire pressures for 32mm and 38mm tires.  12 list members responded with reported rider weights, and actual 32mm and 38mm front & rear tire pressures.  I put the information into an Excel file and compared the actual tire pressures to the tire pressures calculated using F Berto's 15% Tire Drop method assuming the following:

1.  The 12 members reported the RIDER weight, not the total bike weight.  I used a 26 lb BIKE weight (typical road lightweight steel tubing) to get th TOTAl weight for the calculation

2.  I used  45%/55% front/rear distribution for all members except 1 who reported an Upright use on 38mm tire (used a 40/60 split for this)

3.  I used the 32mm curve Berto published for the 32mm tire and used an extrapolation for the 38mm tire.  I caluated the front and rear pressures based n the front and rear weights (using the distribution) and a slope and intercept for each tire size, i.e.,  

pressure = slope * weight + intercept

The executive summary is:

The majority of the riders tire pressures are with 6 to 8 psig of the pressures calculated by Berto's method.  There were 5 outliers out of 24 pressures reported (12 reports x 2 pressures per report), see below.  This indicates the majority of the responders are using tire pressures based on the 15% tire drop method.

The 32mm uses tend to OVER Inflate the Front tire and UNDER Inflate the REAR tire wrt to Berto's method.  The 32mm users may want to verify their Rear pressures wrt to Berto's method.

The 38mm tire users tend to inflate both Front and Rear closer to Berto's method than the 32mm users.

The 4 outliers were:

1 32mm user over inflated the Front by 11 psi

2 32 mm users under inflated the Rear by 9 psi and 11 psi

1 38mm user under inflated the Front and Rear by 14 and 24 psig respectively.

If any one reported Total Weight or has a weight distribution other the 45%/55% F/R (except for the 1 38mm case of an upright), let me know and I will adjust the file.

I purposely did NOT include the Excel file since the list members responding did not know their information would be used.

PM me for individual data.  If all agree, I can include the Excel file, somehow.

John Hawrylak

Woodstown NJ

[rob markwardt]

I also crashed recently on a too low pressure (for me) Hetre.  I was pulling into a little side/stop and and as I turning in the tire buckled and I went down hard on my side.  No damage to bike but there were two pinch flats in the tube and a sore left leg for me.  I've been riding pumped up Nifty Swiftys this past week...just a little different.  

[stonehog]

One more data point. I weigh 165 and my bike (AHH) is about 31lbs with normal gear. I ran the tires at 40 front and 60 rear, but let them drop to 30/50 on occasion before topping them. I have since switched to Bon Jons (35mm), and run them about 35/45.

Brian Hanson
Seattle, WA

[John Hawrylak]

Brian

For the 35mm tire, your 35/45 psig values are each 8 psig lower than the 15%Tire Drop Pressures (TDP) for 191 lb Total Weight (165 + 31), assuming your AHH is a 45%/55% Front/Rear weight distribution.  The % of the 15% TDP is -19% Front, and -15% Rear. 

Here are the calculated 15% TDP for the 3 weight distributions, with a comparison made to the 45%/55% distribution

                 Wt Dist     15% TDP Front    Rear     Your Values Front    Rear    Diff, Your-15%TDP  % of 15%TDP

Rando    45%/55%                    43psig  54psig                       35psig  45psig        -8psig   -8psig    -19%,  -15%

Racing   40%/60%                    38psig  57psi                         

City        35%/65%                    34psig  62psig

The -8 psig under inflation on F &R is at the lower border of most of the members, i.e, their pressures are slightly higher than yours accounting for weights.

John Hawrylak

Woodstown NJ

[Ron Mc]

good job assembling the data - it shows we think much alike, Frank Bert was pretty sharp, and dipping too low can be dangerous.  

FWIW on the Barlows, I've cornered very hard and fast on narrow rims (Open Pro) at the pressures I run.  The biggest concern with running too high pressure is wearing through expensive rubber too quickly.