Accuracy of pumps

[Polar]

Not many talks about how accurate a pumps or gauge is and according to Cycplus their pumps are within +-1 psi which I don't believe is correct since I get 3 psi different readings on a Cycplus AS2 pro pump and Topeak D2 gauge.
Which one is most accurate?

 

[Stihldog]

pressures can be off when pumping up the tire (the pump gauge reads high) and it some times seems more difficult to pump up the tire

Yeah, that’s happened to me also. I can only think that it’s the sealant issue, valve core issue, or clearance to the CushCore. ?????

 

[RebornRider]

So was the Topeak calibrated at the same time, and can it even be re- calibrated? And what happened to the Jaco?

The Topeak has not been calibrated. Calibration would probably cost more than the gauge, The one I have is accurate from the factory. Sometimes you get lucky!

(Why do I claim the Topeak is accurate? Because it matches my Span, which was professionally calibrated recently.)

Nothing happened to the Jaco. I opened it up to the see the miniature bourdon tube inside. ;-) It is not as accurate as the Topeak.. Sometimes your luck runs out.

(Why do I claim the Jaco is inaccurate? Because it does not match the Span, which was professionally calibrated recently.)

 

[KnollyBro]

Yeah, that’s happened to me also. I can only think that it’s the sealant issue, valve core issue, or clearance to the CushCore. ?????

In the end, I am not sure being so precise in pressure matters that much to me as I am not planning to ride in any World cup races this year. Sometimes, it's just nice to know what the tire pressures are for a pre flight mental check, so if I do crash, I can't blame my tire pressure for being way off.
I use Fillmore valves so there is a possible issue there. I have even tried drilling out a 1/2" hole threw the Cushcore to accommodate the popet valve only to find out the Cushcore moved inside the tire.

 

[Downhillr]

I agree with @Paulquattro , but if I had to put money on it, I'd go with the Topeak D2.

However, the important thing is not how accurate the gauge is but how consistent it is. The D2 is very consistent in my 20-years experience. I spend quite a bit of time getting the tyre pressures that work well for me. Once I have them, I record them and use my D2 to check and set before every ride. If I'm going somewhere markedly different or with trail conditions different, then I may alter the tyre pressures by a psi or two. Because I always use the D2, I don't have to worry about its accuracy.

I use the same gauge to measure and set tyre pressures on my car as well. The gauges found at petrol stations and companies that fit your tyres appear to vary enormously, so I always overfill and then correct with the D2.

Like Steve, I also use the D2 gauge, however, whichever gauge you use the consistency is indeed most important so using the same gauge is important in order to set your pressure consistently prior to each ride. BTW, the same holds true for your fork/shock gauge.

 

[Stihldog]

In the end, I am not sure being so precise in pressure matters that much to me as I am not planning to ride in any World cup races this year. Sometimes, it's just nice to know what the tire pressures are for a pre flight mental check, so if I do crash, I can't blame my tire pressure for being way off.
I use Fillmore valves so there is a possible issue there. I have even tried drilling out a 1/2" hole threw the Cushcore to accommodate the popet valve only to find out the Cushcore moved inside the tire.

Because I run the CushCore Plus on the rear, 2.6” Assigia, Filmore valve, MucOff sealant, 35mm wide rim, I need to drill a small clearance hole in the CushCore. Yeah, alignment is tricky sometimes.…and that tire can be a pita to get on.

Need to use those CushCore levers to chase the bead around on the special bike cave garbage can. . Of course I can’t inject MucOff sealant through the Filmore valve so I just pour in 80-100 ml.

Did I mention that it’s a pita?

 

[irie]

... Of course I can’t inject MucOff sealant through the Filmore valve so I just pour in 80-100 ml.

Did I mention that it’s a pita?

Which is why after trying Fillmore valves I removed them and went back to Presta.

Presta valve cores are dirt cheap so if they jam just remove them and put new ones in.

Can't be arsed.

Bye-bye Fillmore valves

As said here: What did you buy your ebike this week? Bought four new Presta valves. Why? Changed four tyres and at same time fitted Fillmore valves. Clogged up several times while injecting Muc-Off tubeless sealant, probably due to Muc-Off sealant particle size. After fitting Fillmore valves...

www.emtbforums.com

 

[Stihldog]

Which is why after trying Fillmore valves I removed them and went back to Presta.

Presta valve cores are dirt cheap so if they jam just remove them and put new ones in.

Can't be arsed.

Bye-bye Fillmore valves

As said here: What did you buy your ebike this week? Bought four new Presta valves. Why? Changed four tyres and at same time fitted Fillmore valves. Clogged up several times while injecting Muc-Off tubeless sealant, probably due to Muc-Off sealant particle size. After fitting Fillmore valves...

www.emtbforums.com

I suppose it’s my stubborn side or my inability to admit defeat …but those Filmore valves work great on both bikes. MucOff sealant injected through the Filmore is not good …almost impossible.

Sometimes I wouldn’t mind a glitter bomb during a burp…but the combination of Filmore and Mucoff seems to work. Rarely do I loose psi.

But, if anyone has perfected smell-test, or lick-test for psi…let me know.

 

[Zimmerframe]

if anyone has perfected smell-test

Presumably pressure above local atmospheric pressure = fart ?

Not sure how that really helps though.

 

[Stihldog]

Presumably pressure above local atmospheric pressure = fart ?

Not sure how that really helps though.

I’d be more concerned after bear hibernation ends, which is soon. I’d worry less about glitter bombs.

Btw, I recommend fresh air in your tire. Anything else could be embarrassing.

 

[KnollyBro]

Because I run the CushCore Plus on the rear, 2.6” Assigia, Filmore valve, MucOff sealant, 35mm wide rim, I need to drill a small clearance hole in the CushCore. Yeah, alignment is tricky sometimes.…and that tire can be a pita to get on.

Need to use those CushCore levers to chase the bead around on the special bike cave garbage can. . Of course I can’t inject MucOff sealant through the Filmore valve so I just pour in 80-100 ml.

Did I mention that it’s a pita?

Is it fair to assume the MucOff has glitter in with the sealant that plugs the Fillmore valves? I am still stuck on Stans and dont have any issue with the Fillmore valves and filling/toping up the sealant. I do seem to lose pressure and have to pump up one or two of my tires, sometimes as much a 3-4 PSI a week but I am not ripping of a tire with Cushcore in it to look for a small leak like that. I think Stans should do better. I dont like to change unless its something people can point out and say "wow.... thats cool!" and sealant does not fit the bill.

 

[Stihldog]

Is it fair to assume the MucOff has glitter in with the sealant that plugs the Fillmore valves? I am still stuck on Stans and dont have any issue with the Fillmore valves and filling/toping up the sealant. I do seem to lose pressure and have to pump up one or two of my tires, sometimes as much a 3-4 PSI a week but I am not ripping of a tire with Cushcore in it to look for a small leak like that. I think Stans should do better. I dont like to change unless its something people can point out and say "wow.... thats cool!" and sealant does not fit the bill.

I think MucOff has something that resembles strands of wool. (No glitter which makes me sad ). Stan’s seems thicker, maybe with chunks of something?

 

[Stihldog]

… seem to lose pressure and have to pump up one or two of my tires, sometimes as much a 3-4 PSI a week

That would drive me crazy. I’d be spraying the sh*t outta that tire/rim/valve until I could sleep soundly.

Besides the valve core, the valve stem needs to be secured. After I’m satisfied with secure seating, (hand tight ),I add a 1/4 turn to the valve nut with pliers …careful not to damage the rim.

 

[irie]

... I do seem to lose pressure and have to pump up one or two of my tires, sometimes as much a 3-4 PSI a week

Same here, no big deal because always connect pump and check tyre pressures before every ride, takes 2 minutes max.

 

[Downhillr]

Same here, no big deal because always connect pump and check tyre pressures before every ride, takes 2 minutes max.

I still use Stan’s (after trying Orange & another brand).
I do find the Maxxis DD and Schwalbe Gravity casings with 4oz sealant may lose a couple psi in a couple weeks (my auto tires can also lose a couple psi over a few weeks) so I figure its not a big deal and just check ‘em before I ride.

 

[KnollyBro]

That would drive me crazy. I’d be spraying the sh*t outta that tire/rim/valve until I could sleep soundly.

Besides the valve core, the valve stem needs to be secured. After I’m satisfied with secure seating, (hand tight ),I add a 1/4 turn to the valve nut with pliers …careful not to damage the rim.

I am mostly satisfied with 70% of the 11 wheels I have holding air. I have taken tires off too many times in search of WHY I have a few of slow leaks (replaced rim tape, replaced the O ring on the valve stem, replaced the sealant and even tried regular presta valves) but as @irie says, I always check my tire pressure before a ride so I am not going to lose sleep over it (it does piss me off a lot tho but not enough to deal with a Cushcore tire before I have to replace it). I will never give up on Fillmore valves. They were too expensive!

 

[irie]

... I always check my tire pressure before a ride so I am not going to lose sleep over it ...

Moi non plus.

 

[Downhillr]

I still use Stan’s (after trying Orange & another brand).
I do find the Maxxis DD and Schwalbe Gravity casings with 4oz sealant may lose a couple psi in a couple weeks (my auto tires can also lose a couple psi over a few weeks) so I figure its not a big deal and just check ‘em before I ride.

Here’s an interesting article regarding inserts… when I switched to the newly released Schwalbe radial tires with Gravity Pro casing (Magic Mary) I ditched the inserts and increased my air pressure about 3 psi. I found the radial tire offers quite noticeable grip and comfort benefits, especially if you're patient in maximizing advantages of a properly set up, quality suspension system (I have Fox 38 fork (updated to 2025 Grip X2) and a custom tuned Fox Evol X2 shock.

 

[Downhillr]

Here’s an interesting article regarding inserts… when I switched to the newly released Schwalbe radial tires with Gravity Pro casing (Magic Mary) I ditched the inserts and increased my air pressure about 3 psi. I found the radial tire offers quite noticeable grip and comfort benefits, especially if you're patient in maximizing advantages of a properly set up, quality suspension system (I have Fox 38 fork (updated to 2025 Grip X2) and a custom tuned Fox Evol X2 shock.

Oops, forgot link…. https://www.pinkbike.com/news/burni...nent-manufacturers-stand-on-tire-inserts.html

 

[jackamo]

I tend to just pump my tyres up till they are hard , then let a little air out multiple times till they are too soft then pump them up a bit more . Worked for over 50 years

 

[Stihldog]

I tend to just pump my tyres up till they are hard , then let a little air out multiple times till they are too soft then pump them up a bit more . Worked for over 50 years

I know a guy who does exactly that.
Its was so much easier when my tires were solid rubber.

But I do vary the psi slightly for different conditions. Snow seems to always need low psi.

 

[Arminius]

Hmmmm, Glitter = Microplastics?

Good the industry started looking into it:

Bioglitter™ and Peaty’s Develop Ground-Breaking Non-Microplastic Tyre Sealant for Cyclists - Bioglitter

The team at Peaty’s, a producer of high-performance cycling products, has been working with Bioglitter™, a developer of biodegradable cosmetic glitter, to develop a brand new to market plastic-free tubeless bike tyre sealant. This ground-breaking and resilient new formula containing...

www.bioglitter.com

 

[irie]

Hmmmm, Glitter = Microplastics?

Good the industry started looking into it:

Bioglitter™ and Peaty’s Develop Ground-Breaking Non-Microplastic Tyre Sealant for Cyclists - Bioglitter

The team at Peaty’s, a producer of high-performance cycling products, has been working with Bioglitter™, a developer of biodegradable cosmetic glitter, to develop a brand new to market plastic-free tubeless bike tyre sealant. This ground-breaking and resilient new formula containing...

www.bioglitter.com

View attachment 154336

Shouldn't that be called Gary?

 

[Old Codger]

Not many talks about how accurate a pumps or gauge is and according to Cycplus their pumps are within +-1 psi which I don't believe is correct since I get 3 psi different readings on a Cycplus AS2 pro pump and Topeak D2 gauge.
Which one is most accurate?

My two floor pumps read about 3psi more than the D2 but I think it’s due to the way they measure. The D2 measures direct from the tyre and the floor pump measures from what’s in the tube between the connector and the pump.

 

[NMNomad]

While I can and do appreciate absolute precision. If I am using my cycplus, I am just trying to get enough inflation to safely get back to where I can properly fix the issue without making it worse. With that in mind, it has already proven its worth by helping a rider in our group get back home, while we were 6 miles out on trail. It may not be absolutely precise. But, it is absolutely worth the money for my use case.