XC 29er - help to go below 9kg

Discuss light weight issues concerning mountain bikes & parts.

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adios1984
Posts: 6
Joined: Wed Oct 24, 2018 6:55 pm

by adios1984

Hi

I'm looking for some ideas, on how to bring the weight of my xc 29er below 9kg.
This year i was racing on gx Eagle, but now i'm a lot stronger and lighter, so i have figured out, that i can go back to 1x11, which should save me some nice grams, plus i already have SRAM 1175 cassette (325g).
I'd also replace GX Eagle gripshift with XX1 11 speed trigger with lightweight foam grips, as well as GX derailleur with XX1 11 speed.

With this i'll be able to hit app. 9,3kg. But how to go below 9?
I'm not willing to replace the frame and the wheels. The same goes for tires. I have already tried lightskin tires, and they are not reliable enough, so i stick to snakeskin, exo etc versions.

Maybe to replace brakes with...? Or something else?
MTB .PNG

by Weenie


scant
Posts: 185
Joined: Fri Apr 30, 2004 2:05 pm
Location: S.Wales UK

by scant

hope X2 lightweight disc brake rotors would loose around 65g per rotor compared to your current rotors & unlike some lightweight rotors they work perfectly. brake drag down an alp & they'll be fine.
the xt disc brakes also look on the heavy side compared to XTR, but as always thats a big price increase for such a weight loss.

other than that have you already changed to titanium & alu bolts? you can upgrade them slowly so its not a massive expense

also look at things like stock chainstay protectors & replace with a narrow strip of 3m 2228 tape. I dropped 30g on my hardtail

absolute black aheadset cap & bolt is 4g & not that expensive.

hope that helps!

adios1984
Posts: 6
Joined: Wed Oct 24, 2018 6:55 pm

by adios1984

Thanks

I have also thought about brake rotors. With Hope i'll have to use some light 6 bolt to centerlock adapter, or go for something like SRAM 160mm centerlock (112g pc).
For frame eprotection i'm already using 1mm thick transparent tape, only on chainstay and under bb.
And i guess i'll have to start collecting some Ti bolts :)

For the brakes i thought about Magura MT8, which i can get for app. 250euro for scomplete set.

Edit:
Since you mentioned brake rotor, it reminded me that i have one XTR 160mm rotor lying somwhere around.
I have found and weighted it. 116g.
I'll buy 2nd one then, and use a pair of 160mm XTRs, which will give me additional -53g.

ooo
Posts: 822
Joined: Sat May 21, 2016 12:59 pm

by ooo

alloy link housing for shifting cable
'

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LeDuke
Posts: 1537
Joined: Sun Oct 07, 2012 2:39 am
Location: Front Range, CO

by LeDuke

Your thru axles are super heavy.

Get some bolt on J & Ls on eBay. Make sure you have the right standard, though.


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adios1984
Posts: 6
Joined: Wed Oct 24, 2018 6:55 pm

by adios1984

Goo call on the axles.
I have ordered new front (36g) and rear (40g) axles. Easy -69g.

In the meantime i have also found super ligh stem in my part collection. Force teamlite (company from Czech Republic) 90mm +/-10. With steel bolts it weights at only 89g.
16g for nothing.

peroni
Posts: 31
Joined: Thu Sep 29, 2016 8:31 am
Location: Italy

by peroni

Replace Reba with SID WC. Should net you at least 200 grams plus wallet is lighter too. win win!
Bianchi Oltre XR2 2014 Campagnolo SR

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Klaster_1
Posts: 786
Joined: Mon Aug 15, 2016 10:25 am
Location: Russia

by Klaster_1

You can easily drop 100g on saddle with Berk Lupina. Bottles are not usually counted towards total weight. Also, your wheels are heavy, there are 950-1100g options available.

wheelzqc
Posts: 270
Joined: Thu Jun 09, 2011 6:51 pm

by wheelzqc

LeDuke wrote:
Wed Oct 24, 2018 9:58 pm
Your thru axles are super heavy.

Get some bolt on J & Ls on eBay. Make sure you have the right standard, though.


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I don't find anything when I search for J & Ls on eBay. Any links ? Interested, thanks.

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Klaster_1
Posts: 786
Joined: Mon Aug 15, 2016 10:25 am
Location: Russia

by Klaster_1

wheelzqc wrote:
Thu Oct 25, 2018 12:26 pm
I don't find anything when I search for J & Ls on eBay. Any links ? Interested, thanks.
See here.

adios1984
Posts: 6
Joined: Wed Oct 24, 2018 6:55 pm

by adios1984

Does anyone knows, if there is lighter option for GXP support?

Edit:
It seems that only option here is TOKEN Triple8 GXP/HTII BSA support, with the weigth of 69g. That would be -41g, and the price is the same as SRAM support.

adios1984
Posts: 6
Joined: Wed Oct 24, 2018 6:55 pm

by adios1984

So far Weight reduction is going well. I have managed to get it down by a total of 624g, a i didn't even touched the drivetrain yet.
Component exchanged so far with real weights:
1. I have shortened handlebar by 50mm from initial 720mm (now 122g). -8g
2. Replaced axles 15/12mm with bolt on (now 46g / 41g). -60g
4. Decided to try new tires. Hutchinson Black Mamba TR RR 29x2.0 (now 505g / 514g). -123g
5. Replaced brakes with XTR M9000 (now front 192g / rear 210g). -208g
6. Replaced front 180mm brake rotor / rear 160mm with 160mm XTRs (now 116g / 116g). -60g
7. M520s replaced with Exustar 215Ti (now 240g). -150g
8. Swapped stems (now 89g). -15g

I'm curious how these tires will perform. Advertised weight is 510g, so th ereal one is almost spot on. The rubber feels quite sticky. Sidewall is not as paper thin like Schwalbe liteskin, but also not as thick as snakeskin. The threads are not visible at all (unlike on schwalbe liteskin).

For the drivetrain i think i'll swap rear derailleur and shifter for XTR M9000. It's lighter and cheaper than XX1. Casette and chain will be SRAM, as planned in the beginning.
This will place me somwhere at 8.7kg.

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Klaster_1
Posts: 786
Joined: Mon Aug 15, 2016 10:25 am
Location: Russia

by Klaster_1

Solid savings :thumbup:
adios1984 wrote:
Tue Oct 30, 2018 9:02 pm
Casette and chain will be SRAM, as planned in the beginning.
Take a look at PYC SP-1101 chain, it's lighter than SRAM.

Connor
Posts: 38
Joined: Fri Jan 13, 2012 6:47 pm

by Connor

You could save a solid chuck of weight by getting new wheels. A set of these rims https://www.lightbicycle.com/XC925-asym ... s-mtb.html, novatec straightpull hubs, sapim cx rays, and alloy nipples would set you back around 7-800 dollars and weigh around 1100 grams.

peroni
Posts: 31
Joined: Thu Sep 29, 2016 8:31 am
Location: Italy

by peroni

But OP said in the very first message he's not willing to replace frame or wheels.

I'm surprised no mention of fork swap since that would be a big weight save albeit with a hefty price.

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Bianchi Oltre XR2 2014 Campagnolo SR

by Weenie


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