Hi

Relative beginner here looking to upgrade a Giant Trance Advanced 2 (2015):
http://www.giant-bicycles.com/es-es/bikes/model/trance.advanced.27.5.2/19160/77191/#specifications

Cassette SRAM PG1050 11×36
Chain KMC X10
Crankset SRAM S1000, 24/38 w/ MRP 2x Guide

Basically I want to get more speed going downhill (my priority right now, as I am sometimes spinning out on descents) but don´t want to lose too much climbing ability either.

Since I practically never use the second chain set, I am open to losing that, but I am trying not get too obsessed by bike weight, and who knows, may ride steeper technical climbs in the future 🙂

Any advice on my options?

Thanks!

If your spun out in a 38 that will be at a decent speed (think I could get up to about 55kph on that)
Generally if it’s not just a fire Road to go faster you need to ride the terrain smoothly, conserve speed and lay off the brakes.

Any advice on my options?

Triple chainset.

Chill out and enjoy the view! Spinning out on a 38 is hauling in my book. My top end is a 32, can’t say I’ve ever been bothered by spinning out.
In answer to your question, you could just replace the 38 with a 40 or a 42, but you need to be sure the front mech can take it. If you loosen the bolt, does it slide high enough to accommodate the extra diameter? You may well need to look at options for a different front mech, and of course maybe a slightly longer chain.
Wouldn’t bother with a triple, of you are not really using the 24.

If your spun out in a 38 that will be at a decent speed (think I could get up to about 55kph on that)
Generally if it’s not just a fire Road to go faster you need to ride the terrain smoothly, conserve speed and lay off the brakes.

I don´t ride a lot of down hill fire roads and even when I do, only rarely get the bike to 55. I guess they are not steep enough or long enough.

Is there a point when it become counter productive (in terms of speed) to keep pedalling?
Also, when does aero positioning really start to count?

Also, when does aero positioning really start to count?

Long time after technique 😉 take a look at some world cup dh vids, Aaron Gwinn in leogang and niko from the world Champs in Norway – both chainless.

Go 11spd, then get yourself an E13 9-44T cassette and go 1x upfront. Are you really spinning out a 38T on off-road descents? In the UK?

Is there a point when it become counter productive (in terms of speed) to keep pedalling?
Also, when does aero positioning really start to count?

Only on really smooth downhills.

There was one back in the late 90’s where Nico Voulilloz adopted a tuck on a section in the middle of a world cup where everyone else was pedaling flat out. He lost time on that section but made up more time in the following technical wooded section.

If you’re spinning out a 38t chainring then I’d go out in search of some more interesting descents, I think 32-12 is my top gear, and I still rarely use that, if I’m on a path that allows those sorts of speeds then I’m usually not fussed about a fast time.

http://gears.mtbcrosscountry.com/#27.5I1371I1

Calculates 54kmh @ 120rpm for your setup.

I don´t ride a lot of down hill fire roads and even when I do, only rarely get the bike to 55

Where are you riding to get to those speeds if it’s not firetrack, and are you sure you’re spinning out?

Basically I want to get more speed going downhill (my priority right now, as I am sometimes spinning out on descents) but don´t want to lose too much climbing ability either.

Keep the running gear as is.

Fit longer forks to slacken out the head angle, tyres are important…sometimes you’ll want a semi slick out back, think about anglesets to further slacken things out and give you added confidence (speed)….next, and this is controversial although Liteville do it….but stick a 26 inch wheel inn the bank, it drops the BB (the bike will feel like it’s in rails) and by dropping the back slightly you further slacken the front again….you can actually end up with a Trance with a head angle of 65-66 degrees without buggering around with anglesets.
They’re then great fun in the DH sections and the DW/Meastro link rear suspension copes admirably.

^^^ I’d suggest looking at some skills courses before all of that sorry to say.