Anyone out there bulding WW Trail bikes

Discuss light weight issues concerning mountain bikes & parts.

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prebsy
Posts: 1044
Joined: Tue Oct 23, 2012 10:52 pm
Location: there or thereabouts

by prebsy

I just got my hands on a new stumpy frame and I'm really loving this blend of capability and efficiency. So my main question is how are people going about picking light parts for trail bikes? I've built plenty of road bikes and some XC rigs and for those disciplines parts clearly specify if they are approved for (road,XC,gravel, enduro ) use. I'm struggling to find any indications as such for trail bikes. Mainly bars stem saddle. For example my renthal carbon fat bar ( 31.8 ) is over 200g @750mm, surely a sub 100g unit from the german companies isn't going to cut it but >200g also looks like there is a lot of room for improvement.

1llum4
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Joined: Thu Jul 12, 2018 6:00 am

by 1llum4

For bar & stem the german companies will still be your best bet for lighter option rated for trail/all-mountain usage.
Depending on bar width you want, schmolke bike ahead and mcfk have option around 130-150g
For stems Intend or Newmen have good lightweight option and if you want a super short stem the renthal is not too heavy.

For the rest I think it will mostly depends on the type of trails you ride that will dictate how much closer to XC parts you can use for tires, rotor size, wheels and cranks.

And if you are okay with a shorter drop, you could go with a lighter dropper post option like the Fox transfer SL or Bike yoke divine sl.

by Weenie


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Hexsense
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Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

It's pretty much downcountry bike right? Stem and bar I'll let other answer. But the rest of dreambuild downcountry bike are:
1) Inline rear shock, no picky back style. Example: Manitou Mara Inline (or Manitou Mcleod) or Fox DPS. Skip Rockshox Sidluxe, it's too XC focussed.
2) Fork: Fox 34 SC 2022 or Rockshox Sid Ultimate 120mm travel are around 1.5kg, about 200-400g lighter than 130-140 travel fork.
If you think they are still too XC focussed and not trail enough, Check Manitou R7 Pro or Manitou Mattoc.
3) Sram XX1 crank even if you use Shimano Groupset.
4) Grip is not something to overlook. Sqlab 711 R weight 59-89g a pair depend on size. Most lock on grip weight 130-200g a pair.
5) Cassette: Gabaruk or Sram XX1. Big weight to be saved here.
6) Brake: Don't go with sub-par 2 piston XC brakes. Keep it 4 piston. At the minimum, Shimano 4 piston. Or better, Hayes Dominion A4.
7) Tires! Some weight over 1kg each, some about 700g and some XC-ish tire weight 500-600g. Go middle ground. 2.4" 700g-ish, like Wolfpack MTB Race/ MTB Cross. Schwalbe used to be light, the new update make them really heavy.
8 ) Dropper post: Most modern XC bike still use rigid carbon seatpost but most down-country bike these days have dropper post already.
There are 3 stand-out light options
Fox Transfer SL-> really light, but seat is either up or down. No lock in between.
9point8 Fall Line R -> nearly as light as Fox and has intermediate position. But reliability/durability issue is reported quite often.
BikeYoke Divine SL -> about 40-50g more than 9point8, and require more lever effort. But reliable.

ghostinthemachine
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Joined: Thu May 07, 2015 9:18 pm

by ghostinthemachine

Have a quick Google for Dangerholm. Think he's done 10kilo DH bikes...

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

by scant

there tends to be more lightweight trail bike builds on the french forum

eg
https://light-bikes.fr/viewtopic.php?f=45&t=3060

&
https://light-bikes.fr/viewtopic.php?f=45&t=2319

User avatar
F45
Posts: 1077
Joined: Wed Jun 08, 2011 6:08 am

by F45

Stick with 11 speed if you can. 12 speed adds about half a pound for no reason.

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prebsy
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Joined: Tue Oct 23, 2012 10:52 pm
Location: there or thereabouts

by prebsy

scant wrote:
Sat Dec 25, 2021 1:00 am
there tends to be more lightweight trail bike builds on the french forum

eg
https://light-bikes.fr/viewtopic.php?f=45&t=3060

&
https://light-bikes.fr/viewtopic.php?f=45&t=2319
Some nice inspiration here although teasing out from google translate is limited. It looks like my stumpy frame actually puts me well ahead of these builds so I clearly need to get crap together and get my bike down from 13kg lol.

The 11 speed idea is interesting, gx axs is really nice but really really heavy.

Here's my dirty bike
Build:
Stumpy S3
Suntour Auron 35 140
Magura MT Trail Sport (180/180)
Renthal Fatbar Carbon 31.8 745mm +10mm (55mm stem)
AXS GX / XT 165s
Bontrager Line Elite 30 / Pirelli Scorpion S

13.2kg / 29.1lbs

Image

freepk
Posts: 256
Joined: Thu Feb 18, 2016 1:31 pm

by freepk

Hi,

This is my unfinished setup, maybe this can help:
Image
Image

1llum4
Posts: 302
Joined: Thu Jul 12, 2018 6:00 am

by 1llum4

Fork with a lyrik would be 50-100g saved and you could save 50g with a Vecnum nivo dropper with similar travel.

The rest of the build look well optimized for weight saving. good job. Will be looking foward to see the full build.

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prebsy
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Joined: Tue Oct 23, 2012 10:52 pm
Location: there or thereabouts

by prebsy

Freepk, sweet build. Looks like you'll have an extremely capable bike @ 12.1kg.

Here is my sheet with actual weights.
Wheels
The wheels are obviously needing replacement I just keep waffling on what are the right wheels but the far sports "XC" wheels with the 30mm internal really interest me... like 700g savings.

Fork
My fork is a bit porky but it's really burly and includes the fender so incredibly low on the list for g/$ and I actually like the performance of the suntour and i can swap 130/140/150/160 air springs in literally 10minutes.
Image

thegolfather
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Joined: Fri Jun 25, 2021 6:40 am
Location: Guam

by thegolfather

I will make a sheet like this for my bike so I can see as I change the parts eventually. I wonder if I can find the weights of the stock parts

User avatar
prebsy
Posts: 1044
Joined: Tue Oct 23, 2012 10:52 pm
Location: there or thereabouts

by prebsy

you can find a lot of the weights online but if you don't weigh yourself you won't really know. I usually start with R2-bike as they have scale shots which is usually better than manf specs. Spread sheet is your best friend. I typically do some heavier calcs for replacing parts like sorting by g/$ and even considering the resale value of the part I'm swapping out.

OnTheRivet
Posts: 732
Joined: Sat Jul 24, 2010 9:41 pm

by OnTheRivet

I had a first Gen Santa Cruz 5010 with q 140mm travel Pike that weighed just under 25lbs with 2.35 Ikons. With a beffier tires still in the low 25's. This was a true trail bike 180 rotors 780 bars, I could ride anything my friends on their Bronson/Nomads could. Current bike is a Revel Rascal 140/130 29er. The frame is really heavy but I like it. After a smart parts pick it's 27.5lb in a Medium with 2.35 tires.

freepk
Posts: 256
Joined: Thu Feb 18, 2016 1:31 pm

by freepk

Almost finished my trail bike :-) Todo: rear brake, seatpost hose.
Less than 12kg at this point :-)
Image

CGT
Posts: 342
Joined: Fri Jan 05, 2007 5:33 pm
Location: Stockholm, Sweden

by CGT

Very sweet! Last are really doing something special with their carbon fibre frames. What's the component spec?

by Weenie


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