Ask the experts

[grskier]

These tires are rated up to 60psi. All the gravel here is accessed by pavement anyway. To just ride gravel you gotta drive out somewhere and then park. I'm on gravel after a mile or two of pavement from the house. I have run lower pressures and it just feels too slow to me.

Most of that may be psychological, which sometimes is reason enough. YMMV

[Dumbest Known Time]

These tires are rated up to 60psi. All the gravel here is accessed by pavement anyway. To just ride gravel you gotta drive out somewhere and then park. I'm on gravel after a mile or two of pavement from the house. I have run lower pressures and it just feels too slow to me.

I think the standard argument when people claim that lower pressures feel slower is just that you're not feeling your fillings rattling out of your teeth. All the bro-science would indicate that lower pressures are proven to be quicker as long as you hit the sweet spot. Faffing around with the Silca pressure calculator led to me trying some dramatically lower pressures than I typically would have and I was pleasantly surprised. That said, do whatever damn well please. Its just bikes.

https://silca.cc/blogs/silca/tire-pr...ator-explained

[Whiteroom_Guardian]

Hmmm, the calculator said I should be at 42/40 psi. I've been around 50-55. Might have to experiment.

[singlesline]

I think that’s about right: it might feel slower because of the smoothness, but if you had a power meter and a speedometer you’d see improvements over the same terrain.

[jm2e]

When you guys replace a spoke, do you jut cut a hole in the tape and then “patch” over it with a bit of tape? Or do you pull off all the old tape and start over?


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[toast2266]

When you guys replace a spoke, do you jut cut a hole in the tape and then “patch” over it with a bit of tape? Or do you pull off all the old tape and start over?


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I do a full retape. I've never had good luck with tape patches.

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[Boissal]

Hmmm, the calculator said I should be at 42/40 psi. I've been around 50-55. Might have to experiment.

I started in the mid 50s on my gravel steed and a buddy who spends a lot of time out told me to drop that shit. Running 35 to 40ish depending on terrain now but even on pavement the comfort gains vastly offset any loss of efficiency IMO. Makes it possible to bunny hop stuff without fearing for your C-spine.

[toast2266]

I know nothing about gravel tire pressures, but world cup XC guys run around 15 psi, and those tires aren't *that* different than gravel tires. If higher psi was faster, those guys would definitely be running higher pressures. It's not apples to apples, but it's at least apples to some other apple adjacent fruit.

[jdadour]

Step 1: Go to Silca Calculator and input your specs
Step 2: Find out that you should be running pressures much lower than you thought
Step 3: Do it, and go ride

I and others have likely found out we should be running lower pressures. Give it a shot.

I run 60 psi in my 32mm road tires, 42 psi in my 40mm semi slicks, 34 psi in my 48mm gravel tires, and 28 in my Race King 2.2s. For reference, I'm 175 lbs


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[Huskier]

Eating crow about my Kryptotal and on a roll with dumb questions: I cannot keep air in my front tire. It's losing at least 10lbs/24hrs. Not a fast enough leak to lose air while riding but still kind of annoying. I've tried adding sealant twice to no avail. Going to try breaking and reseating the bead, are there any special tricks to get it to seat properly? I typically use an air compressor to do the job. It's like I got 99% of the way there... But just short. Failing that, is there any way to troubleshoot a valve core short of just sticking a new one in?

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[skaredshtles]

<snip> Failing that, is there any way to troubleshoot a valve core short of just sticking a new one in?

Soapy water

[D(C)]

Eating crow about my Kryptotal and on a roll with dumb questions: I cannot keep air in my front tire. It's losing at least 10lbs/24hrs. Not a fast enough leak to lose air while riding but still kind of annoying. I've tried adding sealant twice to no avail. Going to try breaking and reseating the bead, are there any special tricks to get it to seat properly? I typically use an air compressor to do the job. It's like I got 99% of the way there... But just short. Failing that, is there any way to troubleshoot a valve core short of just sticking a new one in?

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I bet it’s damaged tape. If air is coming out the spoke holes or around the valve stem, that’s probably the culprit.

[Andeh]

I bet it’s damaged tape. If air is coming out the spoke holes or around the valve stem, that’s probably the culprit.

Seconding this.

[Andeh]

When going over my bike in advance of this coming weekend's road trip, I discovered the lower brake mount on the fork is more than halfway stripped out. For now, I've put in the longest bolt that will fit ~30mm, had a 25mm in there before, with a shitload of loctite. I'd conservatively guess there's only about 5mm of working threads. So, a couple questions:

1) Zeb 29 lowers are out of stock everywhere. Is SRAM/RS likely to have a secret stash of them that my local shop might able to access through service rather than b2b?

2) is there any way to repair this that will preserve the ability to remove the brake caliper? I.E. not fill the hole full of JB Weld

3) how crazy would I be to ride it in the current state? Part of me thinks that's fucking stupid, the other part thinks if I hadn't gone over the bike yesterday, I would have kept riding it as it was unawares.

For the record, I don't think that I did the damage, but I can't prove my theory, and bringing it up to the shop in question will result in either hurt feelings or blanket denials. I had them build up a bike with this fork, and when I got it back, I found multiple glaringly bad things wrong, including loose bolts and the front brake was mounted with with a +20mm adapter, for a 200mm rotor and a 200mm native post mount fork. The brakes were takeoff Code Rs, and I know the rear of those calipers makes it hard to screw the bolt in straight. When I later swapped the fork out, I remember noticing that it was really difficult to get the lower bolt out (must have been cross threaded).

[Robik]

When going over my bike in advance of this coming weekend's road trip, I discovered the lower brake mount on the fork is more than halfway stripped out. For now, I've put in the longest bolt that will fit ~30mm, had a 25mm in there before, with a shitload of loctite. I'd conservatively guess there's only about 5mm of working threads. So, a couple questions:

1) Zeb 29 lowers are out of stock everywhere. Is SRAM/RS likely to have a secret stash of them that my local shop might able to access through service rather than b2b?

2) is there any way to repair this that will preserve the ability to remove the brake caliper? I.E. not fill the hole full of JB Weld

3) how crazy would I be to ride it in the current state? Part of me thinks that's fucking stupid, the other part thinks if I hadn't gone over the bike yesterday, I would have kept riding it as it was unawares.

For the record, I don't think that I did the damage, but I can't prove my theory, and bringing it up to the shop in question will result in either hurt feelings or blanket denials. I had them build up a bike with this fork, and when I got it back, I found multiple glaringly bad things wrong, including loose bolts and the front brake was mounted with with a +20mm adapter, for a 200mm rotor and a 200mm native post mount fork. The brakes were takeoff Code Rs, and I know the rear of those calipers makes it hard to screw the bolt in straight. When I later swapped the fork out, I remember noticing that it was really difficult to get the lower bolt out (must have been cross threaded).

I would try to clear the threads with the tap. Then helicoil if it's damaged beyond re-tapping. BTW, I had same issue with one of the earlier ZEB brake mount that I bought used.

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[Roxtar]

I bet it’s damaged tape. If air is coming out the spoke holes or around the valve stem, that’s probably the culprit.

Seconding this.

X3
Pretty much every TL failure I've had has been tape related.

[Roxtar]

I would try to clear the threads with the tap. Then helicoil if it's damaged beyond re-tapping. BTW, I had same issue with one of the earlier ZEB brake mount that I bought used.

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Helicoil is a great permanent fix. Threads will now be steel instead of alum.
Just be careful on the drilling out process. Drilling aluminum slightly oversize tends to grab the bit, causing it to drill deeper or off angle.

[Andeh]

Helicoil is a great permanent fix. Threads will now be steel instead of alum.
Just be careful on the drilling out process. Drilling aluminum slightly oversize tends to grab the bit, causing it to drill deeper or off angle.

Thanks guys, I'll look into it.

[rideit]

Just had a ‘hail Mary’ repair thought.
If the threads are beyond pooched, theoretically, one could epoxy/JB weld a longer threaded rod into the fork mount, and secure it in reverse, with a nut at the end of it instead of a bolt head.
Just a wild thought.
Something I would try for myself as a last-ditch effort.

[J. Barron DeJong]

Just had a ‘hail Mary’ repair thought.
If the threads are beyond pooched, theoretically, one could epoxy/JB weld a longer threaded rod into the fork mount, and secure it in reverse, with a nut at the end of it instead of a bolt head.
Just a wild thought.
Something I would try for myself as a last-ditch effort.

JB Weld can be drilled and tapped, so you could fill the current hole completely and start fresh if you were inclined to go the JB Weld route.

[Roxtar]

JB Weld can be drilled and tapped, so you could fill the current hole completely and start fresh if you were inclined to go the JB Weld route.

Way, way harder to get holes drilled and tapped correctly than helicoil.

[toast2266]

X2 on helicoil. It's really the only viable repair option for that situation.

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[J. Barron DeJong]

Way, way harder to get holes drilled and tapped correctly than helicoil.

For sure. I’d be going heicoil.

Just saying that if you ended up going the JB Weld route for whatever reason, it can be drilled and tapped, which gets you back to where you started.

[XXX-er]

it IS a brake part and brakes are kind of important

[toast2266]

JB weld repairs are for areas that won't kill you if they fail. Maaaaybe a rear brake mount. Definitely not a front brake mount.

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