Lightweight build - suggestions please

Discuss light weight issues concerning mountain bikes & parts.

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wadsy
Posts: 98
Joined: Mon Aug 17, 2009 11:21 pm

by wadsy

I'm building an old Santa Cruz Superlight. I'd like to build it as light as possible BUT with an eye on the spend. I know the two often don't really go together!

Here's my planned spec below. I'd welcome suggestions for cost effective alternatives where appropraite :)...Especially with choice of BB type and cranks please!

I plan to run it 1x9 as I thought removing shifter, cable, front mech and chainring would reduce the weight!

Frame: Santa Cruz Superlight

Fork: RS SID (28mm) or Pace RC39

Headset: Chris King 91g - already got
Stem: Syntace F99 - with ti bolts 109g - already got
Handlebar: Easton CT2 Carbon Riser - already got
Grips: Foam - already got

Brakes: Avid Ti (V-brakes)
Brake Pads: Ceramic compound
Brake Cables:
Brake Levers: Avid Ti

Shifters: Sram X0 - just one side for rear mech
Front Derailleur: NA
Rear Derailleur: Sram X0 193g
Derailleur Cables:
Cassette: XTR M970 11-34 242g
Chain: KMC 9SL 246g - already got
Crankset: Middleburn RS8 X-Type?...XTR M970?
Bottom Bracket: ???
Pedals: Crank Bros Egg beater 4Ti 168g - already got

Hub Skewers: KCNC 45g - already got
Wheels: Mavic Crossmax (tubeless ready rims) - already got
Tyres: Rocket Ron Pacestar (tubeless)
Tubes: NA

Saddle: Flite Transalp - already got
Seatpost: USE Carbon Alien + Shim 143g+37g
Seatpost Binder:KCNC 11g


Thanks in advance for any input :)

Cheers
Last edited by wadsy on Thu Aug 21, 2014 7:12 pm, edited 1 time in total.

youngs_modulus
Posts: 512
Joined: Wed Sep 20, 2006 1:03 am
Location: Madison, WI USA

by youngs_modulus

If you're losing the front derailleur and buying a new chainring, you should really get a narrow-wide ring. Race Face, Wolf Tooth and Absolute Black all make well regarded options.

If I was looking for a cheap and cheerful crank that was also light, I'd get the new Race Face Turbine Cinch:

http://www.bikerumor.com/2014/06/23/new ... your-ride/

I've got the carbon fiber version, the Next SL, and I adore this system. The bottom bracket, axle and chainring mounting are especially well thought out. Retail (including a 32t narrow-wide direct mount ring) is $270, which I think is pretty reasonable. If you own Middleburn parts, though, you're almost certainly in the UK; I don't know what the UK MSRP is. But the cranks are Canadian, so you'd still be sourcing from within the Commonwealth!

With a direct-mount ring and a BSA bottom bracket, the entire setup weighs 720 grams, which is pretty good IMHO. Plus, you'd be able to fit it to almost any bike you bought in the future...Race Face offers a huge array of bottom brackets and axles...you can even put these on a fat bike.



Cheers,

Jason

wadsy
Posts: 98
Joined: Mon Aug 17, 2009 11:21 pm

by wadsy

Thanks very much for the reply and info. Jason :)

I'm not necesarily looking for new parts, second hand will do!...to increase my options.

Would you say that an external bb set-up with hollow axle is going to be lighter than a square taper st-up like Tune for example?

Cheers

youngs_modulus
Posts: 512
Joined: Wed Sep 20, 2006 1:03 am
Location: Madison, WI USA

by youngs_modulus

Oh yes, the hollow aluminum axle (7068, in fact, a very sexy alloy) is dramatically stiffer than a solid steel square-taper axle. The external cups help a bit, but the large diameter axle is what really makes the difference. Torsional and bending stiffness increase with the cube of the radius, so a 30mm axle can be made significantly stiffer, stronger and lighter than a solid axle.

But if you don't want to buy a new crank, just get a narrow-wide ring and a bottom bracket to fit your Middleburn crank. It'll probably be heavier than the Race Face crank I mentioned, but perhaps not by much. But you really do want a narrow-wide ring if you're not running a front derailleur or chainguard.

Does your copy of the X0 rear derailleur include a clutch for the cage? If you want to avoid dropping chains, that's the other critical piece of the puzzle.


Cheers,

Jason

wadsy
Posts: 98
Joined: Mon Aug 17, 2009 11:21 pm

by wadsy

youngs_modulus wrote:Oh yes, the hollow aluminum axle (7068, in fact, a very sexy alloy) is dramatically stiffer than a solid steel square-taper axle. The external cups help a bit, but the large diameter axle is what really makes the difference. Torsional and bending stiffness increase with the cube of the radius, so a 30mm axle can be made significantly stiffer, stronger and lighter than a solid axle.

But if you don't want to buy a new crank, just get a narrow-wide ring and a bottom bracket to fit your Middleburn crank. It'll probably be heavier than the Race Face crank I mentioned, but perhaps not by much. But you really do want a narrow-wide ring if you're not running a front derailleur or chainguard.

Does your copy of the X0 rear derailleur include a clutch for the cage? If you want to avoid dropping chains, that's the other critical piece of the puzzle.

Cheers,
Jason


I don't actually have a Middleburn crank, it was just one of the options I thought of as well as the M970 :)

I've marked the parts I've got so far as "already got" :wink:

So, I don't have the X0 mech either. How do i tell if one has the 'clutch' you mention?

Cheers :)

jooo
Posts: 1510
Joined: Wed Feb 02, 2011 3:48 am

by jooo

There are no 'clutch' 9 speed RD's, but a Shimano Dynasys RD will work with SRAM 9 speed shifters with a small mod to change the cable pull:
Image

youngs_modulus
Posts: 512
Joined: Wed Sep 20, 2006 1:03 am
Location: Madison, WI USA

by youngs_modulus

Jeez...if you're definitely buying a crank--new or used--why not get the RF Cinch?

Jooo makes a great point about the dearth of 9-speed clutched derailleurs. But since you don't have either shifters, derailleur or cassette marked as "already got," why not buy the 10-speed versions? Surely they're easier to find.


Finally, Sram calls their clutched derailleurs "type 2."
https://www.sram.com/news/introducing-s ... derailleur

TheRookie
Posts: 911
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

Just a few thoughts/musings
1/ CK headset is heavy (noting you have it already).
2/ Something like the AEST levers are lighter than the Avid
3/ Shifter - have you considered a twist shift, not everyone's favourite I know.
4/ Tyres - The Ron isn't that light, obviously a tyre needs to perform though!
Of course there is always weight to be saved in the details like bolts, cable lengths etc.
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

bm0p700f
in the industry
Posts: 3650
Joined: Sat May 12, 2012 7:25 pm
Location: Glermsford, Suffolk U.K
Contact:

by bm0p700f

For light tyres I have had good use out of conti X-king supersonic (420g each) and Geax barro race tyres (410g each).
Middle burn cranks are light I think my old RS2 which I have with a single ring weigh in at something like 454g. If only I put a Ti BB with it.
The Race face Next SL is very light and with narrow wide chainrings you have a light and stiff chainset. Lighter than XTR will ever be.

You could save even more weight and go single speed, honestly you don't need more than one gear.

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