Ask the experts

[carlh]

Are you accounting for the pressure drop from attaching the pump? Test by setting pressure disconnecting and immediately reconnecting. 4psi drop from a pump connection is not unreasonable.

[volklpowdermaniac]

Are you accounting for the pressure drop from attaching the pump? Test by setting pressure disconnecting and immediately reconnecting. 4psi drop from a pump connection is not unreasonable.

i thought that was bupkiss for lack of a better term? that the air you hear disconnecting is just in the line itself, shouldn't change pressure at all?

not suggesting your wrong either , just sort of thought that was one of them myth busted things?

[skaredshtles]

i thought that was bupkiss for lack of a better term? that the air you hear disconnecting is just in the line itself, shouldn't change pressure at all?

not suggesting your wrong either , just sort of thought that was one of them myth busted things?

The air loss comes when you *attach* the pump. Air leaves the shock to fill the hose...

Disconnection does *not* resut in air loss from the shock.

[Dee Hubbs]

Let's say your fork has 140cc of volume, or 8.50 cubic inches
You pump it up to 85 psi, the pump reads 85 psi, and when you unscrew the pump the fork valve closes and any extra air in the hose and pump cylinder escapes (and that's the a hiss you hear)

Your fork has a 8.50 cubic inch cylinder with 85psi, and your pump cylinder and pump hose now have zero psi.
Once you screw your pump onto the fork, the fork valve opens and that 85psi is now spread between the 8.50 cubic inch fork leg, AND the previously 0.50 cubic inch empty pump cylinder and hose.

Now your pumps 0.5 cubic inch camber and your fork 8.50 cubic inch chambers equal 9.0 cubic inch, and share that same pressure that was in your fork. The increased volume (with that same pressure) reduces the pressure overall in the fork tube by 5.88%.
If you unscrew the pump without a stroke, the fork pressure will be reduced by the 5.88% and now only has 80 psi.
Do this over and over again and you just keep emptying air from your fork into you pump, and emptying your pump into the atmosphere when you detach it from the fork.

[volklpowdermaniac]

Let's say your fork has 140cc of volume, or 8.50 cubic inches
You pump it up to 85 psi, the pump reads 85 psi, and when you unscrew the pump the fork valve closes and any extra air in the hose and pump cylinder escapes (and that's the a hiss you hear)

Your fork has a 8.50 cubic inch cylinder with 85psi, and your pump cylinder and pump hose now have zero psi.
Once you screw your pump onto the fork, the fork valve opens and that 85psi is now spread between the 8.50 cubic inch fork leg, AND the previously 0.50 cubic inch empty pump cylinder and hose.

Now your pumps 0.5 cubic inch camber and your fork 8.50 cubic inch chambers equal 9.0 cubic inch, and share that same pressure that was in your fork. The increased volume (with that same pressure) reduces the pressure overall in the fork tube by 5.88%.
If you unscrew the pump without a stroke, the fork pressure will be reduced by the 5.88% and now only has 80 psi.
Do this over and over again and you just keep emptying air from your fork into you pump, and emptying your pump into the atmosphere when you detach it from the fork.

got it , that all tracks, forgot the attaching part obviously pressurized the pump. will just keep an eye on it

thought experiment . wonder this: if you attach pump with handle pressed in - will you get marginally more accurate initial
reading as less air is allowed to leave fork into the pump? obviously you'll eventually get to same place with first drawback on pump but....

[XXX-er]

Yeah when you check air pressure in a tire its no problem cuz the volume of air is relatively big and the pressures are usually much lower but on suspension the airchambers are SO small/ the pressures so much higher that you will bleed out a bunch of air everytime you check it SO I don' t see how to do it with a guage or the guage on a pump ?

I look at how much sag i have when i sit on the bike, with my Roxshox SD I could tell it was leaking by sitting on the bike and checking weighted sag, so I would have to put more air in it after the bike sat overnight could be 20-30lbs to get that correct weighted sag ( I think 19mm ? ) of course the guy rebuilding it said there was nothing wrong but I imagine he always sez that, whatever he replaced its been way better

With my ZEB I more or less do the same thing by checking the tell-tale-ring on the fork leg to see how much of the travel I go thru in a normal ride ( I want at least 5" ) at a place I normaly ride and it has always been the same, I actualy use way less air in the ZEB than recommend to use more of the available travel

[volklpowdermaniac]

Yeah when you check air pressure in a tire its no problem cuz the volume of air is relatively big and the pressures are usually much lower but on suspension the airchambers are SO small/ the pressures so much higher that you will bleed out a bunch of air everytime you check it SO I don' t see how to do it with a guage or the guage on a pump ?

I look at how much sag i have when i sit on the bike, with my Roxshox SD I could tell it was leaking by sitting on the bike and checking weighted sag, so I would have to put more air in it after the bike sat overnight could be 20-30lbs to get that correct weighted sag ( I think 19mm ? ) of course the guy rebuilding it said there was nothing wrong but I imagine he always sez that, whatever he replaced its been way better

With my ZEB I more or less do the same thing by checking the tell-tale-ring on the fork leg to see how much of the travel I go thru in a normal ride ( I want at least 5" ) at a place I normaly ride and it has always been the same, I actualy use way less air in the ZEB than recommend to use more of the travel

interesting thoughts for sure. could def use a better system

[Roxtar]

I read an interesting post about this from a mag (don't remember who) here.
He came up with a way to a zero air loss pump connection.
Screw the pump head in slowly, a little bit at a time, while lightly pumping. At first, the air will leak out but you'll eventually get to a point where the pump head seals, but doesn't open the valve yet. It will just build up pressure in the hose.
When you get to this point, pump till the gauge reads the same as the expected fork or shock pressure.
Now you can screw the connector in till it opens the valve.

[Dee Hubbs]

Pump your fork until 85psi.
Remove your pump.
Attach your pump, read the pump indicator that says 80.75psi.
Know that your pump's volume reduces the total pressure pressure by 5%.
Stroke it up to 85 psi, ride, be happy.
Next time you attach your pump, look for 80.75 to confirm that its holding pressure.

[Canada1]

Pump your fork until 85psi.
Remove your pump.
Attach your pump, read the pump indicator that says 80.75psi.
Know that your pump's volume reduces the total pressure pressure by 5%.
Stroke it up to 85 psi, ride, be happy.
Next time you attach your pump, look for 80.75 to confirm that its holding pressure.

We truely are bike nerds. The stuff we geek out over makes me happy.

[toast2266]

Realistic temperature changes over the course of a ride can change your fork pressure by 10 psi. Once you come to grips with that, it's a lot easier to not fret so much over small inaccuracies in the inflation process.

[XXX-er]

interesting thoughts for sure. could def use a better system

which would require a built-in guage ( something else to weigh grams & fuckup ? )

so I can't measure how much air is in the shock after the fact I can only measure what i put in

I know that 165lbs of air will give me a 19mm weighted sag measurment on the shock o-ring so if i got 19mm on the tell-tale O-ring I probably still have 165lbs of air so I consider the O-ring is the guage

I don't need to know how much air is in there exactly, I just need it to work right

[summit]

Short torso for height, long legs/arms for height

Size up or down on frame for height?

[toast2266]

Short torso for height, long legs/arms for height

Size up or down on frame for height?

Up.

That more or less describes me. Among other issues, I find that if I size down, I end up having a ton of seatpost exposed. That means my raised saddle position ends up being pretty rearward, especially on bikes with slacker actual ST angles. I also find that having longer limbs means I can move around on the bike a bit more, so having a bigger bike feels a little less cumbersome than it might if I had stubby little arms and legs.

[Andeh]

Concur, size up. I'm the opposite proportions-wise (especially inseam), and would size down when I'm not smack in the middle of size charts.

[carlh]

Any secret sources for bearing? I want to do my i9 hydra rear hub and enduro shipping is pricy.

[toast2266]

Any secret sources for bearing? I want to do my i9 hydra rear hub and enduro shipping is pricy.

Lots of places carry enduro bearings. Jenson, etc. You can probably find some with free shipping.

[Andeh]

The issue with Hydra bearings is they use a few funky sizes in the rear hub that only they use. You can buy a bearing kit directly from i9 or other shops.

[climberevan]

I acquired some wheels for my Krampus, and the seller didn't note that the front hub had the stupid "torque caps". So.... they are both now 21.5mm +- .1mm.

[smmokan]

I'm a huge fan of wearing the Camelbak Chase Vest for long'ish rides where I don't need to carry a ton - super comfortable and I barely know it's there. Has anyone tried out a larger-capacity running vest for all-day rides where you carry a bunch of stuff with you (tools, jacket, lunch, etc)?

Bumping this... I bought a larger Camelbak vest (the Octane 10) and tested it out over the weekend with a heavier load. Specifically, I put in about 2L of water, air pump, small first-aid kit, water filter and my relatively small mirrorless camera/lens combo. I have to say, I'm not a fan of how the shoulder straps dug in with more weight- it was significantly less comfortable than the Chase vest. I'm currently using the Lab Austere USWE-sytle pack, courtesy of Marshal, and it was a much better option. I'll definitely stick with that for now since it's been tough to beat.

[summit]

Up.

That more or less describes me. Among other issues, I find that if I size down, I end up having a ton of seatpost exposed. That means my raised saddle position ends up being pretty rearward, especially on bikes with slacker actual ST angles. I also find that having longer limbs means I can move around on the bike a bit more, so having a bigger bike feels a little less cumbersome than it might if I had stubby little arms and legs.

Concur, size up. I'm the opposite proportions-wise (especially inseam), and would size down when I'm not smack in the middle of size charts.

Make any difference if it is for a novice female rider?

[toast2266]

Make any difference if it is for a novice female rider?

In that case, I'd probably go down. By that I mean, if she's on the line between sizes, go with the smaller one. But if, by her overall height, she's squarely on a size, stick with that size - don't go with a bike that's too small.

[Sandbox]

Thinking of booking a trip with the family to Arizona Early / mid April. Never been. Kid is just over 4 so looking for a family friendly ( vrbo with a pool) area but also one that has some decent biking close by. What area should I be looking in that has places I can get to relatively quickly for some biking but also close enough for some light hikes and typical food / shopping style stuff for the fam?


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[rideit]

Sedona/Flagstaff/Grand Canyon.

[alewi11]

The desert in the Hawes trail system is super pretty that time of year. There are some family friendly rides as well as some really good techgnar. Also some pretty good hikes. Sedona would be fun but an absolute zoo that time of year. Airbnbs in Sedona would be multiples of what something in the PHX valley would be. You could consider Prescott. I think most of their trails would be riding by then.