PSI On The Fly, maybe a favorite pump lead...

[Alex K]

The Road-ish Riv Rubber Radius thread got me thinking about PSI adjustments while on longer rides.  Last month I rode my 56cm 650b Atlantis from San Francisco to Olema via Mt. Tam and the Bolinas Ridge Fire Trail (which was about 13 miles and our main gravel section of the day) and back to SF via Samuel P. Taylor and Fairfax.  A glorious 75 mile-ride (80% road/20%gravel) with 6000 ft of climbing on a perfectly sunny, temperate day.  We stopped at Pantoll Station midway to the top of Mt. Tam and made coffee and had some decadent pastries and smoked salmon.  Everything was perfect.....except for one five mile stretch at the end of the Bolinas Ridge Fire Trail.  A "relentless descent" characterized by obstinate cows, hard-packed dirt that could only be described as rutted washboard, and lots of time spent death-gripping my TRP brake levers on my newly mounted 666mm Crust Towel Rack bars.  Once past this stretch, the ride returned to its' earlier glory and we headed home through idyllic Marin County.  A great day of mixed-terrain riding.  In retrospect, though, I can't help but think that I could have avoided the unpleasantness of that 5-mile descent had I just thought to lower my PSI before getting on the fire trail.  Being that the first half of the ride and the final 35% of the ride would be on the road, I started (and finished) my day out at 42 PSI on my 48mm Rene Herse Switchback Hill Endurance tires.  Now I'm kicking myself for not lowering the pressure significantly.  And I figured that this would be a good place to ask for others' experience with mid-ride PSI changes.  Is this something that folks do regularly or are y'all more inclined to choose a PSI that will work on mixed terrain?  And if frequent PSI changes are the norm, what pumps are your favorites?  Since most (?) Riv-Riders seem to be almost obsessed with bags as they are with their bikes (I rode with my Fabios Chest L on this particular day) I figure that pump size is not as important as pump efficiency. 

Thanks for your consideration.

Alex

[Garth]

I don't know your weight is Alex but 42 PSI for any 48mm tire seems a bit high for any tire. I've let some air out of tires in rare circumstances but it's not something I want to do on a regular basis. If I do let air out I'll keep it there for the rest of the ride. In "someone else's shoes" though, I could do anything applicable to the circumstance.  I've only used the Topeak Road and Mountain Morphs since 2000. They're rather large and bulky, but they function just like a mini floor pump, so you're pushing down against the ground, rather than across your other arm. Their frame mount is stupid though so you have to buy your own side mount with bottle cages. I may buy a Silca Tattico to try as I rarely use a pump on the road anyways. it's one of the few mini hose type pumps that have a lever-lock head, rather than a screwy screw-on. I have no idea how effective it is though using arm to arm resistance without trying it. Basically I haven't tried a bunch of pumps, let alone bags, so no not every Riv rider is so inclined to try every one out there. What you seen in print and other media offers a very limited view of what the real World actually is, in all It's glorious variety.

[Brian Turner]

I agree that 42 psi seems high for a 48mm endurance casing. If you're running tubes you may be wary of punctures or pinches so you'd likely run higher, but I think you can safely get away with lower pressures. I'm 175 lbs and ride tubeless setups on most of my bikes. The bike I ride the most is tubeless with 48mm RH Juniper Ridge endurance casings, and 30 psi is the MOST pressure I put in them, and that's for rides that are mostly paved. If I'm doing gravel or dirt trails, I'll drop the pressure down to 24 psi. I don't really ever change pressures mid-ride, but often have to pump up a bit if it's an overnight or multi-day trip.

I'm one of those bag-obsessed riders you mentioned. I use the Lezyne Micro Floor Drive HV pump and thread it onto a Topeak Shuttle digital gauge as the "head" of the pump - I just attach it whenever I need to use the pump. It's a pretty nice, compact system and I find it to be way more accurate than my shop pump head (which is the Park INF-2 Shop inflator).

[Will Boericke]

I am guilty of not having a great gauge on any of my pumps at home, so I find myself frequently dropping pressure over the course of a ride until I get to magic carpet feel.  It's particularly disappointing when I get 45 miles into a 55 mile ride before I get there....

[Alex K]

FWIW, I am a hair under 200lbs, and I really dislike that squishy, low psi feeling on the pavement.  Looking at RH's tire pressure calculator now, though, and the recommended PSI rangeis 27-34 from soft to firm.  That is surprising to me, and perhaps it's time to re-evaluate/try some new things!

Alex

[Richard Rose]

On my Clem with 48mm Gravelking SS tires set up tubeless, I leave the house most days @ 35-37 psi f/r. I am 170-175lbs. and most rides are mixed surface with some dirt and some fine gravel but mostly paved. I think this pressure is just about right? I was on a sub24 and had a tire that was loosing air. My Lezyne mini pump just was not cutting it. Another rider pulled out his Topeak Road Morph pump with in line gauge - holy crap! I think I ordered mine that evening & it is fantastic. I did not want it hanging from the bike so it normally resides in my Fifth Season Squall basket sack with other ride essentials. As for accuracy, the morph’s in line gauge seems in sync with my Topeak mountain floor pump.

Sent from my iPhone

On Aug 31, 2022, at 9:03 AM, Alex K <ack...@gmail.com> wrote:

FWIW, I am a hair under 200lbs, and I really dislike that squishy, low psi feeling on the pavement.  Looking at RH's tire pressure calculator now, though, and the recommended PSI rangeis 27-34 from soft to firm.  That is surprising to me, and perhaps it's time to re-evaluate/try some new things!

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[Garth]

I've never used any pressure calculator, but for follies I looked at a few. The Silca is by far the most detailed as it accounts for many vaiables. https://silca.cc/pages/sppc-form

For my 33mm 700c tires with a combined weight of say 195 pounds, the Silca calculator comes the closest to what I ride for any condition,  no more than 39 front, 42 rear at the time of pumping. Albeit, I had chose category 4 "extreme" gravel to get it that low. Otherwise for nice smooth roads it suggests like any other calculator @58/61.  That'd feel rock hard, and I can't think of any place that has nice smooth tarmac for very long.

700x47mm(actual) Big Ben's on the Bombadil I keep anywhere from 25-33 max and over rough terrain I could go lower. They only felt squirmy when I first tried them that way, but I don't notice that anymore.

[Coal Bee Rye Anne]

I'm another Topeak Road Morph user and would also suggest it for ease of trail or roadside use and the inline gauge.  I have two and they've rotated between bikes/bags.  I've used their stock mount on a frame with no bottle bosses just using zipties but yes, on a frame with bottle cages, you'd absolutely want another carrying solution otherwise it's bottle cage vs. pump mount.  I also use some Specialized mini that fits in even the smallest saddle bag and it's been great when needed but as already mentioned, the Topeak acting like a floor pump against the ground is simply much nicer in use.  I haven't tried their MTB Morph but have considered adding one now that one of my two Road morphs has been showing signs of wear and an iffy check valve and not sure replacement parts are readily available for rebuilds.  I'd already tried to take it apart and clean it and may have messed up the gauge calibration and it's worked well enough since but not sure how much it has left in it.  It's the one that has most often been doused in mud and dust so likely just a reflection of it's hard life.  I honestly think most of my personal mid-ride PSI changes have been to increase pressure after getting that squishy, wallowing feeling or anticipation of an eventual pinch flat, but I also tend to go longer periods between inflations and more or less adopted the habit of slightly overinflating to compensate for my own lack of PSI discipline.

Brian

Lawrence NJ

On Wednesday, August 31, 2022 at 11:39:05 AM UTC-4 rmro...@gmail.com wrote:

[J J]

I often adjust pressure during a ride, moving from gravel to pavement or vice versa. I tried the Rene Herse pressure calculations and they’re wildly unpleasant for my riding, weight, and loads. The squishy, wallowing feeling that those pressures result in doesn’t work for me (to be clear, I don’t like super hard tires, either). It feels unstable and precarious and even dangerous. For all that we hear about “cushy” and “supple” on RH tires, I can’t help but think OF COURSE they’re cushy when you recommend such low pressure on 50mm or 55mm tires. My robust Schwalbe Marathons are no less “cushy” than Antelope Hills at such low pressures. I grant that maybe I’m just not getting the super duper cushiness. As Garth reminds us, to each their own: there are lots of ways to be comfy on a bike and people have different preferences and understandings of what makes a comfortable and safe feeling ride. I also use the Road Morph and recommend it. 

[Garth]

Brian, Topeak indeed has a "rebuild kit" https://www.topeak.com/global/en/product/438-PARTS-KIT , but there's no mention of a check valve for any frame pump, only their floor models. I read somewhere that replacing the o-rings and some synthetic grease is all that's needed for the body. The head may need some cleaning too, apparently there are some small balls/bearings in there that allow the head to slide, at least that's from fellow users. Clean and light lube if necessary.

For Road Morphs I bought these brackets

https://www.todson.com/collections/topeak/products/wb-bracket-for-rd-morph-peak-dx-mt-rock-harp-mini-tpd.

There is likely a bracket for the Mtn Morph too but I've been using some Performance Bike shop side bottle brackets i bought years ago that were the same diameter.

Rebuild kits , though you can get just o-rings anywhere local, and they're the most important/relevant.

https://www.todson.com/products/road-mini-morph-rebuild-w-silver-cap-trk-tmm01

https://www.todson.com/products/road-morph-g-rebuild-w-black-cap-trk-rp01

Neither of my Morphs have a gauge but it's easy to tell with experience about what pressure is good enough. If not, stop and add some more !  My 22 year old Road Morph looks like heck as some of the plastic of the retractable handle bits have broken off, but it still pumps. I have to hold the head in position so it doesn't go sideways and lose air too ...... the hose is about as flexible as a chopstick, but the darn thing still pumps. Oh yeah, with large hands it's easy to pinch yourself on the downstroke too. Don'tcha just wanna go buy one ? ( ( (  laughing and crying at the same time ) ) ) .   

On Wednesday, August 31, 2022 at 4:34:11 PM UTC-4 Coal Bee Rye Anne wrote:

[ascpgh]

On longer rides I change inflation for sections with different surfaces, speeds or handing challenges best addressed by such. I have a full size Zefal HPX under the top tube, on the head tube pump peg, of my 700x32 (tubes) Rambouillet and a Lezyne Road modified for the peg and dropout nub on my left rear seat stay on my 650Bx42 (tubeless) Coast rando. I find both pretty handy for a fast stop to add air.  

I'm in the camp of adjusting until it feels right, a gauge reading being a number to start with instead of gospel. If I get lateral sidewall flex when pedaling through a paved turn, I add. If I'm being battered by feeling each piece of aggregate in course pavement or gravel I let some out. Conversely, particularly with the Rambouillet, I grudgingly add air when I sense the potential for rim pinching under a particular load.

On both bikes I'm riding RH tires and have found them rewarding to my perceptions of fine tuning tire pressures. It's ultimately what motivated me to go low trail, front loading, when pumping up the Rambouillet's rear tire above my normal PSI if carrying stuff for overnight or longer because it made harder riding than when unloaded and is a noticeable source of fatigue on long rides. That's when stopping to optimize inflation is not a waste of riding time but rather an investment in reaping the best rewards i can from my bike and the duration of the ride. I've had to work up to to a century ride on the Ram in any season where the bigger tired and wider tolerance of inflation pressures Coast enabled me to ride such distances much more easily and without feeling as worn out afterward.  

Andy Cheatham

Pittsburgh

[Coal Bee Rye Anne]

Hahaha, yes, I do also now recall pinching myself on occasion too!  Thanks for the heads up on the rebuild kit, Garth.    I expect I'll eventually give the Road Morph another service to see exactly what's happening in there but have also wondered whether I'd just prefer one without the gauge, for simplicity and also from tending to just go by feel as well.  When I bought mine the inline gauge was standard fare.  At least at the shop I found it within the past 10 years or so where they only had the one model but I liked it enough to grab a spare.  I guess I just assumed a stuck or clogged valve after experiencing the same kind of issue with my floor pump... the pressure just started backflowing into the handles on both.  The floor pump was a more obvious fix with a quick cleaning and reinstall of the valve and spring while the Road morph has more nooks and crannies.

I've also saved my current floor pump with a simple cleaning and using some silicone plumbing lubricant on the o-ring (after the o-ring stretched and wedged itself between plunger and cylinder a while back.)  I was beginning to look into a newer floor pump until seeing Riv will soon offer one with pretty much the exact features I'd want based on my current needs so now I'm just holding out until theirs is available. 

[Pat Smith]

You can get 3rd party adapters off Amazon or eBay to hold your Topeak Morph next to a bottle cage. I used this one and it works fine: 
https://a.co/d/ckOqV3U

[Alex K]

Lotta great info here.  But, most important of all, WOW HOW BOUT THOSE MINI MORPHS!?!?!?!? While, sadly, the minis no longer come with the psi gauge (according to the folks at REI) the pumping efficiency and ease of use is unparalleled in my road-pumping experience.  I got a non-gauged Mini Morph and also a slightly larger Road Morph G (which has a psi gauge) both of which fit easily in my Small and Large Fabios Chests as well as my BagsXBird piccolo small saddlebag.  This has been a time of revelation for me, personally.  Thanks!

Alex

[Garth]

Topeak makes both Mini's Alex. Always go to the manufacturer when someone tells you something isn't available. It's just not available for REI , based upon whoever decides what to buy and stock all REI stores. Employees usually aren't so inquisitive as to whether or not something is really discontinued by the manufacturer, thus everyone, or just discontinued for their brand of store !

[Luke Hendrickson]

Local (San Francisco) Atlantis owner here! I would love to try out that route for myself.

Since I’m a “heavier” rider at 190lbs., I run the PSI at a steady 35 in the front and 40 in the rear with my 2.4” Maxxis front/2.3” Maxxis rear. I don’t like tinkering with PSI all that much and also run tubes. 

As for a pump… frame pump or nothing for me. Why carry a miniature to shave grams and then spend 30 minutes inflating a high volume tire? I had a vintage Silca with a Campy head (so good and light), but have now opted for a Zefal HPX on both my mid-80s Ritchey mtb and my Atlantis. I like how utilitarian it is as a pump and how easy it is to mount. See attached for the current set up. 

[ascpgh]

Agree on full size pumps versus minis but on my commuter it makes sense to reduct the appealing things that attract pilfering. Oh yeah, weather too. We have that here. I ran a pump behind the seat tube on my yellow '86 RockHopper (before the NORBA geometry infection). Just be sure to have the handle end up/chuck end down when in the position as a fender. 

Previous thread about bagged mini pumps: https://groups.google.com/g/rbw-owners-bunch/c/jBXQT-GxqgM/m/qTmqnCM4DQ

Pictures: https://groups.google.com/g/rbw-owners-bunch/c/jBXQT-GxqgM/m/sIjgQGXKDgAJ

Andy Cheatham

Pitttsburgh