Ask the experts

[Thaleia]

not seeing a 2014 in 26, but the 2013 uses a 184x44 with ccrd tune

sorry, it is a 2012 Giant Trance X1.

I'll be in the idiot thread lol.

[Backward_Banana]

Can an expert please explain to me what are the supposed benefits of a "premium" mountain bike stem? Apart from color, I can't think of anything that could be different performance wise for the same dimensions.

[toast2266]

Can an expert please explain to me what are the supposed benefits of a "premium" mountain bike stem? Apart from color, I can't think of anything that could be different performance wise for the same dimensions.

Some of the cheaper stems are maybe a bit sketchy with how they clamp, which could create issues with carbon bars. A lot of the better stems have you bottom out the face plate at the top, which ensures that there's even pressure on the bar across the clamping surface.

[dcpnz]

^^ yep, i’ve had a cheapie that was pretty rough around edges of casting and the screw holes - nothing insurmountable but needed to clean up burrs before I was comfortable using it - I would hope the 4x premium for brandname would catch things like that in quality control

[smmokan]

They look cooler. And if you (think you) look cooler, then clearly you’ll ride faster.

[Backward_Banana]

Haha, perfect. That does make sense re: the super cheap ones.

[D(C)]

What’s the story with XC tire pressures? In the PB BC Bike Race bike check article, a lot of the pressures seem silly low.

https://pinkbike.com/news/bc-bike-ra...ecks-2023.html

[jamal]

Lighter riders, lighter bikes, tires with less traction, and not going quite as fast or hitting stuff as hard.

Basically, with an xc tire you need as much compliance and contact patch as you can get since the knobs are so small and short. Plus you want that extra bit of cushion on a short travel bike or hardtail.

I'm basically shooting for as soft as I can get away with. Sometimes that's as low as like 18psi in a 2.4 front. Maybe less if it's slippery. Depends on weight and your gauge and all that too.

[Dee Hubbs]

What’s the story with XC tire pressures? In the PB BC Bike Race bike check article, a lot of the pressures seem silly low.

https://pinkbike.com/news/bc-bike-ra...ecks-2023.html

Most are reporting around 19-20psi. That's common in the XC world. If you want to talk low, Nino runs his 2.4 EXO Aspens as low as 17psi with no inserts.

[skinipenem]

Pick a pressure and be a dick about it.
OR
Pick a pump and be a dick about it.
OR
Pick a gauge and be a dick about it.
I fell that as long as you have consistency and adjust your pressure from your “known constant” your good to go.
All my Lezyne pumps are within 2psi at 80psi.
And my Toepeak and PRO hand held gauges also confirm those numbers.
Attachment 464665
Attachment 464666

How close are your lezyne pumps at mountain bike pressures? E.g. 20-30 psi.

Sent from my SM-S908U1 using Tapatalk

[JaytaeMoney]

What does it mean when the bike pedals spin freely forwards and backwards and the hub "buzzing" sound is silent? Broken freehub?

On my ride this morning about half way up the climb I heard a click/pop and the bike completely stopped pedaling, zero torque. I coasted back down to the car and it was dead silent the whole way.

[simple]

Sounds like internal freehub issue. One of a couple pieces could be broken but you can't tell until you open it up. It happens

[climberevan]

Most are reporting around 19-20psi. That's common in the XC world. If you want to talk low, Nino runs his 2.4 EXO Aspens as low as 17psi with no inserts.

I can get away with 18F riding double black rocks, but the XC tires are paper thin and I have real tires. I'm pretty smooth and light, but I assume the pros are even smoother.

Nino does tend to flat a lot... See Cape Epic 2y ago.

It seems like XC MTB racers are still really obsessed with weight. The road world has given up--bikes are often not even at the 6.8kg UCI limit anymore. Certainly a 100g heavier tire is faster than a lighter one that flats.

[John_B]

What's the recommendation for a Shimano XT derailleur clutch adjustment bolt that keeps loosening? Back it out and put a dab of medium strength Loctite on it?

[Jtlange]

What's the recommendation for a Shimano XT derailleur clutch adjustment bolt that keeps loosening? Back it out and put a dab of medium strength Loctite on it?

I would say blue is probably even a tad aggressive. White or purple (purple is designed for low torque fasteners)

[Meconium]

Say you ride a 135mm bike and then a 150mm rear travel bike and then look at a tape measure.
1.5cm doesn’t look like much visually but it feels more much.

why?

[XXX-er]

design & component selection

[XtrPickels]

I can get away with 18F riding double black rocks, but the XC tires are paper thin and I have real tires. I'm pretty smooth and light, but I assume the pros are even smoother.

Nino does tend to flat a lot... See Cape Epic 2y ago.

It seems like XC MTB racers are still really obsessed with weight. The road world has given up--bikes are often not even at the 6.8kg UCI limit anymore. Certainly a 100g heavier tire is faster than a lighter one that flats.

It's funny to me that Kabush is running an SB120 with a 140mm fork.... and Maxxis Aspens.

[toast2266]

Say you ride a 135mm bike and then a 150mm rear travel bike and then look at a tape measure.
1.5cm doesn’t look like much visually but it feels more much.

why?

It's 10% more. 10% is noticeable in most things.

[Dantheman]

It's 10% more. 10% is noticeable in most things.

Plus the 150 mm bike probably has more aggressive geo, 36 mm stanchion fork vs 34 mm, reservoir shock vs non-res, etc. If you take the 150 mm bike and short-stroke it so it only has 135 mm travel it's still going to feel like more travel than the 135 mm bike (assuming the leverage ratio doesn't go crazy in that last 15 mm).

[beaterdit]

..............................................
1.5cm doesn’t look like much visually but it feels more much.

why?

It's 10% more. 10% is noticeable in most things.

That's what she said.

You guys are asleep at the wheel, haha!

[Meconium]

The 135mm is actually more aggressive. Its just mind boggling to me that when you look at a travel change about as thick as a finger, it "feels" so much more compared to a larger rock garden.
Mostly just talking BS of my 10% perception vs physically noticing.
10% of 8 minutes is 48 seconds. If I ran a DH 48 seconds faster the PR would "feel" more then a 10% improvement.
Nevermind the math................

[beaterdit]

In seriousness, I stepped down from a 170/163 bike to a 150/140 bike, with better geometry and arguably better suspension. Big difference for me in carrying speed and just even getting through the rough stuff. For better or worse, building up a new 170/163 bike.

Now I'd like to have a lighter 140/130ish bike...

[toast2266]

The 135mm is actually more aggressive. Its just mind boggling to me that when you look at a travel change about as thick as a finger, it "feels" so much more compared to a larger rock garden.
Mostly just talking BS of my 10% perception vs physically noticing.
10% of 8 minutes is 48 seconds. If I ran a DH 48 seconds faster the PR would "feel" more then a 10% improvement.
Nevermind the math................

A lot of it is just suspension kinematics and shock tunes too. There's a reason why 2 bikes with identical travel and similar geometry can feel entirely different. That difference *can* be compounded by relatively small differences in travel.

[Spencer123]

E-13 helix crank chainring lock ring… I see E-13 sells a tool that no one has in stock for the cassette and chainring. Is this just a standard BB tool or is it some weird proprietary design? Buddy is trying to remove his chainring and it’s not super clear in the manual what tool is needed, trying to figure out if I have the right one to lend but don't have the crank in front of me.

Thanks!