Ask the experts

[toast2266]

My hypothesis: the first bleed wasn't actually good, but the air was trapped in the reservoir. So when you pulled the lever, the piston closed off the reservoir and the air was outside of the pressurized system, so everything felt fine. This probably would have revealed itself with further riding and getting the brakes hot - the air would have worked it's way out of the reservoir soon enough.

Then you tightened the hose some more, and maybe just by virtue of fiddling around at the master cylinder, that air that was trapped in the reservoir made it's way out into the line. Now the air is inside the pressurized system, and it feels spongy. You bled it, got the air out, and all is well (assuming there isn't any air still hiding in the reservoir).

[Dee Hubbs]

If the air bubble is touching brake fluid, it’s in the path of being pressurized. The air pressure will match brake fluid pressure, very quickly, regardless of where it is in the system.

Explain the phenonium of then the customer brings the bike in and says their brakes feel squishy on trail, but feel firm now.
You squeeze the Shimano brakes in the shop and they feel okay, and then you stand the bike up on its rear wheel and squeeze the brake and the lever goes almost to the bar? It really depends on where the bubble is positioned on how much it can effect the system.

When you're bleeding and the funnel is attached to the system, and air (big bubble called the atmosphere) is on the top of the funnel, you can still get a solid hard lever. You really have to pump multiple times to get the fluid too move the air bubble (aka raise the fluid level in the funnel).

[J. Barron DeJong]

Explain the phenonium of then the customer brings the bike in and says their brakes feel squishy on trail, but feel firm now.
You squeeze the Shimano brakes in the shop and they feel okay, and then you stand the bike up on its rear wheel and squeeze the brake and the lever goes almost to the bar? It really depends on where the bubble is positioned on how much it can effect the system.

When you're bleeding and the funnel is attached to the system, and air (big bubble called the atmosphere) is on the top of the funnel, you can still get a solid hard lever. You really have to pump multiple times to get the fluid to move the air bubble (aka raise the fluid level in the funnel).

I’d guess that, as toast is saying below, the air is moving from the reservoir into the pressurized system and vice versa.

If the bubble is on the pressurized side, it’s getting subjected to the same pressure as the brake fluid and it WILL compress, regardless of where in the pressurized section of the system it is.

In the video you link, if they had been able to pressurize that fluid you’d have seen that trapped air bubble shrink as the fluid pressure increased. Same as it would have if that air was trapped in one of the lines leading in/out of that mock up.

[XXX-er]

as oposed to guessing eliminate the possibilities, since you reallly don't know what is wrong just be able to say well it aint this and it aint that if someone asks

a good repair dude/dudess has no ego

[J. Barron DeJong]

as oposed to guessing eliminate the possibilities, since you reallly don't know what is wrong just be able to say well it aint this and it aint that if someone asks

a good repair dude/dudess has no ego

Well I’m not diagnosing. I’m just saying I’m 100% sure that if there is an air bubble in the pressurized area of a fluid system, then that air bubble WILL compress when pressure is applied.

You can use that knowledge while pursuing your diagnosis.

[Wes Mantooth]

My hypothesis: the first bleed wasn't actually good, but the air was trapped in the reservoir. So when you pulled the lever, the piston closed off the reservoir and the air was outside of the pressurized system, so everything felt fine. This probably would have revealed itself with further riding and getting the brakes hot - the air would have worked it's way out of the reservoir soon enough.

Then you tightened the hose some more, and maybe just by virtue of fiddling around at the master cylinder, that air that was trapped in the reservoir made it's way out into the line. Now the air is inside the pressurized system, and it feels spongy. You bled it, got the air out, and all is well (assuming there isn't any air still hiding in the reservoir).

That was my general hypothesis as well. I did ride it around and heat up the brakes a bit after the first bleed and before tightening the fitting, but might not have been enough to dislodge whatever was in there. I still haven't done a crazy long sustained descent on these so we'll see what happens when I get them real hot, but had really sharp controlled braking on steep desert tech so no complaints so far

I also have a pretty scratched up master cylinder from a crash a while back which grazed the bleed port. I was pulling a lot of air with that port on the second bleed, so I flipped the cylinder over and used the port on the bottom side and it seemed much better. So could've also been an issue with not getting a full seal from the syringe

[XXX-er]

My rear brake goes spongy after about a year so I bleed the whole system which works but only the back brake goes spongy not the front

my theory is that becuz I always transport the bike left side down ( non der side) in the truck bed the right side brake lever is the highest spot on the bike up in the air and so over time the bubbles slowly migrate up into that right lever

[jackstraw]

Sram "powerlink" master link is a one time use? Just hearing that now. Sounds like malarkey, but what's the deal? Does it just turn into a regular master link if you use it twice!?

[XXX-er]

I guess its best practise according to SRAM maybe you wana carry a spare which you probably should anhyow

I think them hot pot waxing folk folk use the links multiple times, me I put the chain on the bike squirt it every 3 rides and take it off when its time to replace

[climberevan]

We, the People of the Queso, use links many, nay uncountable, numbers of times. Shimano, SRAM, KMC, and others are good to go.

JOIN US!

[jackstraw]

^ha! I've always reused them...maybe once anyway.

Moving on...broke my brake lever. I thought there was a little set screw to release the pin? Shimano XT. What the hell am I missing? Can't get the lever off.
Is that a cover over the set screw?
Forget it ...yup. Glad I finally bought this pick set a few years ago.

[XXX-er]

Pass, I think they are some kind of MAGA off-shoot

edit: there must be you toobe somewhere to rebuild your brake

[jackstraw]

I dropped the lever spring on the garage floor and lost my mind for five minutes looking for it...then it came into vision with a light

[Dee Hubbs]

Those springs like to fly and hide.
For others looking on, the springs are Right/Left specific. You can buy either side lever to replace your broken one, just make sure you keep the original spring if you can only source an opposite side lever.

[Boissal]

Is that a cover over the set screw?

That cover is impossible to get out without the picks, and even with the picks it's a bit of an ordeal. I usually end up using one of the super pointy xacto knives.

Re: masterlinks, I've lost count of how many times I've reused the same Shimano one but it must be about 30 times by now.

[XXX-er]

I dropped something on floor or carpet every day for 30 yrs so I made a career of this,

don't look for the part just look at the floor

[volklpowdermaniac]

I dropped something on floor or carpet every day for 30 yrs so I made a career of this,

don't look for the part just look at the floor

this is the way.

[CantDog]

Getting ready to install some Hayes Dominions on a Stumpjumper Evo. Looks like some people run into some issues because of the hosing diameter. Anyone with some first hand experience? Figured I’d lube ‘er up and push.

[Andeh]

I had that issue on my Levo. The trick I heard afterwards was very carefully taper the tip of your hose... just a little to clean up any flare from trimming.

[BFD]

I am currently riding a stumpjumper expert
https://www.specialized.com/us/en/st...=320323-199757
I was wondering if this bike would be as capable and any improvement on performance?
https://www.facebook.com/marketplace...73118467297749
they do not make this model yeti anymore maybe a good reason.
I am a decent intermediate rider like to ride everything but wheels stay on the ground. The 6lbs lighter appeals to me although I don't know if that makes a difference.

[teledad]

You’re comparing a mid travel trail bike to a short travel XC bike. The Yeti will climb better (mostly due to lighter weight, the Stumpy is one of the better climbers in its class). The Stumpy will descend better (slacker HTA, longer travel). If you want to get into XC racing or do Leadville the Yeti will be better. Otherwise for an intermediate I’d stick with the bike you have and maybe do some upgrades to save weight.

[Dee Hubbs]

I am currently riding a stumpjumper expert
https://www.specialized.com/us/en/st...=320323-199757
I was wondering if this bike would be as capable and any improvement on performance?
https://www.facebook.com/marketplace...73118467297749
they do not make this model yeti anymore maybe a good reason.
I am a decent intermediate rider like to ride everything but wheels stay on the ground. The 6lbs lighter appeals to me although I don't know if that makes a difference.

IMO not as capable. That Yeti was considered an XC bike before the term Down Country came into existence. 120/100mm is light duty bike, with a steep 67.8 headtube angle on the Yeti vs a slacker 65 on your stumpy. That will be the biggest feel difference.
Trail riding, XC uphill performance (lift weight), rougher down XC trails, but dont expect to smash rock gardens and rougher root sections as easily as your previous Stumpy.
But the specs and condition of that bike are very good looking.

[smmokan]

With the general heft of Yeti's frames, I have a tough time believing that bike is 25# (but it is a nice build). Plus it has a Reverb dropper post, so there's that.

I had a Stumpy Expert a couple years ago and got it down to 28# with some lighter wheels and faster rolling tires... but like the other guys said, your existing bike is one of the better trail bikes out there already.

[XXX-er]

IME with switch infinity on a 5.5 the design really makes those yeti into great climbers and descenders but that was 140mm you may be asking a lot of only 100mm

[BFD]

thanks for the advice. I have not rode enough different bikes to understand geometry or travel. The stumpjumper does seem to do the job. 2 hrs away I may go over and ride it just to feel the difference. Maybe the girlfriend gets a new bike. seems like it would be a good bike for riding smooth trails through the pines.