Building a 29er gravelracer. Chinese frame?

Discuss light weight issues concerning mountain bikes & parts.

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Skorp
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by Skorp

Hi!

Next year im competing in some gravel/super light terrain races. So maintaining high speed over distance is the goal. CX is not allowed, and the "technical" places is abit harsh on a CX.
I have never built a MTB from scratch before, and i need tips on every part i listed. Espesially wheels and frame.
I have a budget of 3000usd, but i want it cheaper.


The parts im most insecure about:
Chinese carbon frame / used frame(Scott scale?): Which frame to choose?
Sun ringle wheels 1720g @ 420usd: Any cheaper or lighter?

The other parts i like and want:
Brakes: XT, 180mm front 160mm rear, XT discs??
Crank: XT with some Narrow-Wide chainring ( the only part i have, but i am willing to change if you have a better choice )
Pedals: Crankbrothers Eggbeater 3
Kasette: XT
Chain: XT
Triggershifter: XT/XTR + mount to fit it to the lever
Handlebar: Ritchey WCS flatbar 540mm
Seatpost: Hylix Taiwan "super light" ebay
Seat: Selle Italia SL XC Flow
Stem: Uno ASA105
Tyres: Schalbe Furious fred 2.25 and Continental Raceking, Maybe even ThunderBurt when they are available

Weight goal: anything under 9,5 is perfect!
Please help me make a fast bike!
I know little, and will be happy for any help i can get!

Cheers, Vegard
Last edited by Skorp on Mon Sep 02, 2013 9:55 pm, edited 1 time in total.

by Weenie


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Colin

by Colin

Have a look at Stans Crest wheels, quite a bit lighter.
Also, I've never had very good luck with Shimano chains, KMC(X10SL) chains are lighter and seem to last longer.

Skorp
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by Skorp

How about shifting quality?

I have only tried Wipperman Connex chains, and almost all shimano chains. Never broken one.

The crest looks nice! I have good experience with stans, i think its the same rims as on the Sun ringle wheelset, altough with lighter hubs and spokes i guess. Atleast they have the right badge on them! :)

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yourdaguy
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by yourdaguy

Get the KMC chains but get light bicycle carbon rims on American Classic hubs if you can afford them. I have 3 sets of Stans (ARCH, Flow, Crest) wheels and 3 sets of Light bicycle wheels. Get the Light bicycle wheels and use a Bontrager rim strip in the front wheel (to prevent possibility of burps). You will be pleased.

I have had problems with Crest rims not being strong/stiff enough and I am 170Lbs and 59 years old. I have tacoed one and blown an Exiwolf completely off of one by hitting a berm. I gave my Chrest wheelset to my 12 year old son who weighs considerably less and does not ride as aggressively. The LB carbon rims are strong as heck and way stiffer. They are as wide on the inside as a Flow but because they don't have the exact Stans shape they hold a tire a smidge wider than a Crest and a smidge less wide than a Flow. They weigh the same as a Crest and the Bontrager rim strip weighs around 35-40 grams more than tape so overall a 37 gram penalty for way stronger stiffer rims than Crest. There is a multi thousand post thread on MTBR about "cheap Chinese rims" that you should check out about the LB rims. I am yourdaguy there also.

Whipperman makes the best quick link, but I am not a fan of their chains.

As far as all the rest of your choices, I am totally an SRAM guy except for XT front ders. The SRAM BB system is way better I have both so I recommend an SRAM crank. The rest of the group stuff is probably a wash. SEat post, get the Cannondale SAVE posts and shim them to fit the frame if you have to. They are by far the best innovation in MTB in the last several years.
For certain parts stiffer is more important than lighter.

HillRPete
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by HillRPete

Skorp wrote:CX is not allowed

How do they define "CX"? Drop bars?
You could maybe run a flat-bar CX with 650b wheels, to fit bigger tyres. Built me one of those, rides very well, and fast 650b tyres are becoming available.

Skorp
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by Skorp

I have sram on my old XC bike, and my AM bike. My Road bike and AM bike have Sram cranks, and they both are squiking. :)
I like Shimano! Only reason i would want to change the Shimano crank ( which i allready posess) Is if it has a big weight penality.
My weight now is heavy.. that is one of the reasons i'm racing next year. To loose weight.. So im abit scared of carbon wheels etc. If they have a weight limit close to my weight then im not interessed.

I weigh 104kg/229lbs now, and i want to go down to 90kg/200lbs until the last big race in August 2014.
My road bike have wheels with 130kg weight limit, and they feel flimsy and bad compared to a weelset without restrictions :)

The definition on CX is pretty much dropbars. Thats the best about CX, other than that a 29er will be just as fast? Just find a low bb 29er frame and im ready to eat milage.

I think i have settled on 29er though. Everyone else is using it, One guy i saw out of 14 000riders in the last race used a CX with flat bars. My guess is super fast in the easy parts, and super slow in the "technical" parts ( Loose gravel, nice trails w/ an occasional rock and root)

A friend have a unused DT Swiss wheelset for sale aswell... might buy that, he says it is 1450grams..

HillRPete
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by HillRPete

Skorp wrote:I think i have settled on 29er. Everyone else is using it, One guy i saw out of 14 000riders in the last race used a CX with flat bars. My guess is super fast in the easy parts, and super slow in the "technical" parts ( Loose gravel, nice trails w/ an occasional rock and root)

Fair enough about the 29er, but why do you think a CX/flatbar/"monstercross" would be slow on the more technical sections? I'm running 2.0" tyres on the 650b, they can munch some terrain. Also the position is very racy because of the CX frame, means good power transfer on the less technical sections.

Here's a pic if you're interested. And I'll stop trying to talk you into it, it's just the concept works very well for me (and the build was cheap) ...
viewtopic.php?f=10&t=107756&start=150#p996104

Skorp
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by Skorp

Looks good, and it is tempting!
Altough, i dont want a mix of parts. If i buy a 500$ frame set, 500$ wheels and 1000$ worth of parts.. Then i want it to fit when im building the bike. Tyre clearence is my main consern. If it "just" fits, and i get a small hit on my wheel, making it rub in the seat/chain stays, then i have to quit my race.
So either a proper CX with flatbars, or a 29er :)

HillRPete
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by HillRPete

Yeah you'd need to check the tyre clearance first hand, of course. When I did my build, this turned out to be the hardest part, actually. All the CX frames seem to claim "massive mud clearance", but this often applies to the seatstays only. Achieving good clearance at the chainstays might force you to use an MTB BB standard, which I could see diluting the manufacturer's "thoroughbred race machine bla bla" claims.

Anyway the Specialized Tricross seems to have some sensible tyre clearance, according to "the internet".

Skorp
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by Skorp

Thats my problem.
I know one guy with a CX, one shop in my area have a cheap CX forsale. I do not have anything to measure up to.
I think a nice and light rigid 29er with one chainring and simple nice shimano brakes is the perfect machine. Tyres which roll good with big volume.

MileHighMark
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by MileHighMark

I just converted my 700C Salsa Vaya to 650B (2" knobbies) and it's a blast on singletrack.
GRAVELBIKE.COM - ride everything

Skorp
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Joined: Thu May 30, 2013 12:54 am

by Skorp

Im not interessed in CX with 650b wheels.

A friend bought a Trek GF Superfly Alu something.. All XT, Fox with 15mm axle and all bontrager parts.. Feels soo good compared to any Scott Scale 900 i have tried. (910, 920 and 950)
I need to read some about geos, and compare.
Which is the lightest and best 29er frame to buy?

HillRPete
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by HillRPete

Skorp wrote:Im not interessed in CX with 650b wheels.

Too bad :D
The new Niner RLT9 looks great for a gravel racer.

by Weenie


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