My bike has a Rockshox Full Sprint remote lockout (hydraulic system). As far as I’m aware there’s no reservoir to capture air as there is in a brake system.
The system needed a bleed at weekend as there was definitely some air in it however it still worked so didn’t bother to bleed it. My bike was left out in the sun for a while when it was seriously hot and from that point on, the lockout button was extremely difficult to depress, like there was too much fluid in it!
Could this be the effect of the air that was in it expanding in the heat? It eventually went back to normal once things had cooled down that evening.
Cheers
Air expands its the ideal gas laws in action. Your system only works properly if you have no air in the system.
Thought so, unfortunately the additional pressure in the system caused a part within the remote to fail! Boooo
This lockout system has been a nightmare but I think I’ve got it figured out after 2 years of sweating, swearing and numerous warranty replacements!
"Could this be the effect of the air that was in it expanding in the heat? "
Just as likely (more likely, even) that it's the oil expanding in the heat.
It's been a long time since I was at school so maybe have my calcs wrong but surely the hot weather wouldn't have much affect on any air in the line, less than 2psi I'd have thought. If oil expands in the heat I could see that potentially causing a problem, oil isn't as compressible as air. I think tillydog is right
I'd be slightly worried if a +-10 degree temp difference caused a lock out to stop working.
<span style="font-size: 0.8rem;"> Given expansion ratios of oil under heat is only in the region of 5-8% across a range of 30deg f to 210deg f.</span>
Could be that the seals in the lever were dry if there was air in the system.
System warms up, viscosity drops which allows air bubbles to migrate up the hose filling the master cylinder with air. As the seals are no longer in oil the master cylinder gets stiff. Keeping trying to press it eventually broke a seal.
It might have worked for a while in the evening simply because a bit of sloshing around got some oil upto the seals bu the damage was already done.
Given expansion ratios of oil under heat is only in the region of 5-8% across a range of 30deg f to 210deg f.
Depends on whether there's anywhere for that 5-8% (or less) to go. I'm guessing the design relies on the piston in the fork moving a small amount to compensate for any change in volume so should be hard to overpressure it unless there's a way to bleed it with the slave cylinder activated whilst the master isn't (i.e. bleeding with a lot of pressure).
I’d be slightly worried if a +-10 degree temp difference caused a lock out to stop working.
Rule of thumb I used to use in pipe design was that anything left in the sun could reach 85C, so thermal expansion was assumed from site minimum up to that over 12h, it's not the ambient temp it's the solar radiation that does it.
