Is 6.5kg too light

Discuss light weight issues concerning mountain bikes & parts.

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bm0p700f
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by bm0p700f

Speaking as someone who has tried to make narrow tyres work in XC races, they don't wider tyres work better and give better control. I am about to try tubular tyres on Geax tubular rims next week, narrow tyres just throw you around and are not good. The ones I was using were a shade over 400g. 8.5kg is easily achievable but lighter will mean comprimises will have to be made.

konky
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by konky

I think I have decided myself that 6.5kg probably is too light. Anyway I want a full suspension frame. I've still got about 2 months before I can buy but currant first choice frame is Specialized Epic Carbon with XX1 drivetrain and XTR brakes, Schmolke post and bars, and AX saddle. Extralite stem. Pedals I'm still not sure about. Might go THM cranks or may stay with S Works. I do care about the overall look of the bike and too many different brand names can look duff. Main wheels possibly Enve but would remove stickers for same brand overkill reasons. The ultimate working machine should also look the nuts.

I'd hope to still stay around 7.5kg and hopefully with much less compromise.

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madcow
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by madcow

Personally I don't think 6.5 is too light to be rideable, however for me personally I think it isn't the best compromise of weight and performance. Usually to hit that weight you have to make some questionable calls, particularly with tires. Depending on the course that may be fine but as a general daily rider I prefer something a bit more... umh, more. I'm currently on a 29er which is at 7.84kgs and while it isn't as light as it could possibly be, I do think it's as light as it can be to give me what I'm looking for.

http://www.bikerumor.com/2012/12/06/fai ... p-project/

Since that article was written there have been a couple of changes, Mcfk handlebar and seatpost, Extralite stem and the brakes got changed to Magura because I just couldn't adjust to the single finger shape of the Kill Hill.

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LAN
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by LAN

I think the spec you suggest look really good (maybe with a stiffer stem), but I think you will end up with a 8,5kg bike at best.

I had a Cannondale Scalpel 29 at 8,8 kg in race trim this year with very comparable spec.
http://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=115344&hilit=scalpel

Scalpel frame is 200g lighter than Epic S-Works WC
Lefty Carbon XLR fork is ca. 100g lighter than Sid Brain

You can save a little weight with lighter seat post, but not more than 25-30g, and lighter crankset, max 150g, and max 100g with a lighter hubs and spokes.

If you are going to get below 8kg, you need to go tubular, or silly tires like Furious Fred 2.0

For rims, the Enve rims are strong, but they are a little narrow at 18mm internal, and the weight is just okay. The Light-Bicycle rims weigh the same, but with 23mm internal. If cost are no object, the new Ax-Lightness clincher rims are very light and wider than Enve.

But as I said, the spec you suggest will build a very solid bike, but if you want to get below 8 kg, you should look to something else than a 29er full suspension.

PS. If you like a quick handling bike (like your Storck is), you should go for a WC edition of the Epic, with shorter chain stays, and steeper head angle, to make the bike feel quicker. In general a 29er fs feels like a tractor, they are fast, but feels slow. My Scalpel is considered to be very agile for a 29er fs, but it´s a long way from my 26er ht, and a looooooong way from my storck road bike.

jooo
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by jooo

I see where you are coming from LAN, comparing things to your build, but you haven't exactly been ruthless with your component selection. A fair bit of weight could be saved from your build without compromising performance. Except for your bar/saddle and XX1 gear, almost every item in your build could be easily exchanged for something lighter, most of which is in the same price bracket as what you're using currently.

Oh, road pedals? :| You must ride some easy trails!

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LAN
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by LAN

My main point was that if you start with a build consisting of these parts:

Epic S-Works frame
Sid Brain fork
XX1 groupset
XTR M987 brakes
Enve wheels

You will not end up with a weight around 7,5 kg no matter how much THM/Schmolke/Ax-Lightness parts you throw at it.

My second point was that his suggested build, will build a very good bike.


Regarding my Scalpel, I know it´s not a super light bike, it´s never been my intension. I have build numerous mtbs under 6,5 kg, but that was not the goal with this one.

Please tell me what parts I should change on my Scalpel to "make it a fair bit lighter" without sacrificing performance, and adding cost. I really look forward to this answer.

In my view, I can only change the wheel set (-200g), the crankset (-150g) and the brakes (-100g), but all will be much more expensive, and also affect durability and performance. ( I doubt the Ax-Lightness clinchers at 305g is stronger and stiffer than my rims at 390g)

konky
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by konky

Thanks LAN for the useful info.

One thing I'm learning is you can build a super light road bike, assuming you've got the budget, without too many compromises but not true with an MTB. You can go 'crazy' light with a road build that does have serious compromises. Crazy light in road is probably equivalent to super light in MTB.

In MTB you can get lighter but not light.

There are lighter full suspension frames than the Epic WS but it's one of the lightest, new XTR brakes likewise, XX1 is pretty much the lightest drivetrain out there, and even with boutique German crank, post, bars etc. I will still end up with a chunk of lead.

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LAN
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by LAN

Yeah, but you are considering the heaviest version of a xc bike, the 29er fs.

You can build a 29er ht, or a 26er fs around 7,5kg with quality parts. But I still think the Epic is a good choice, if I had the contacts to get it cheap I would have bought it, but I´m building a F29 for next year, hopefully around 7 kg.

If you want a light fs, consider buying a 26er Scalpel frame, and use 650b wheels.

The Scalpel frame is 1550g including shock, and a Ax-Lightness 650b clincher wheel with Tune hubs and CX-Speed/Ray spokes around 1100g.

You can end up somewhere between 7 and 7,5 kg.

konky
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by konky

LAN I think I will bite my lip in respect of weight with my proposed fs 29er built around an Epic. One question, as you seem incredibly well informed on the MTB scene. Do you think the new Ax clinchers would be OK for everyday use? That's for trail use and I'm not going to be jumping off cliffs or anything but will ride quite hard. I don't want tubulars for an MTB build.

I use Lightweight Meilenstein tubulars for my everyday road wheels with no probs whatsoever.

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LAN
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by LAN

To be honest I don´t know since I haven´t used them myself. I had the Ax tubulars a couple of years ago, and they are the best rims I ever had on my mtb. The rims were stiff and super light, never had such accelerations on an mtb before.

I would think the clinchers are fine regarding strength and stiffness under normal use, but most ultralight parts have lower tolerance for impacts like crashing, or having a flat, and smash the clincher bead against rocks. The same apply for parts like THM crankset for example, the cranks themselves are stiff and durable, but I think smashing it against rocks will break it sooner than a set of Hollowgrams.

But carbon clinchers for mtb is much better than in road rims, because of no problems with overheating resins because of disc brake vs rim brakes.

Anyway, I look forward to your build

jooo
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by jooo

LAN wrote:Please tell me what parts I should change on my Scalpel to "make it a fair bit lighter" without sacrificing performance, and adding cost. I really look forward to this answer.

In my view, I can only change the wheel set (-200g), the crankset (-150g) and the brakes (-100g), but all will be much more expensive, and also affect durability and performance. ( I doubt the Ax-Lightness clinchers at 305g is stronger and stiffer than my rims at 390g)

It sounds like you were offended by my post which wasn't my intention and honestly, I'm sure your bike works extremely well with that build. It looks like you're missing bar plugs which I'd add (I often use tape, just like you) and then the only thing I'd change would be the pedals. There are sections of trail here that can't really be ridden and walking them in road cleats/shoes would range from being hard to impossible depending on the weather. All really I meant before is that if you're being completely ruthless, there are lighter ways to build a FS 29er without majorly compromising the usability or blowing out the price.

You've said it yourself, there are savings with your wheels, cranks and brakes. Sure you could spend heaps of money to loose grams on those items, but that's not a given if you were starting from scratch.

There are lighter rims than what you're using - even cheap Chinese carbon, let alone if you did spend more money or use tubulars. The money saved using Lasers instead of bladed spokes goes a fair way in making up for using Extralite hubs instead of Tune for example.

If you hunt them down, SWorks cranks can be had for only a bit more than what you're using now and save considerable weight. Even keeping your cranks, weight could be saved with a spiderless chainring.

R1's are another simple weight saving.

You could save weight on your pedals.

On a budget and starting from scratch, there are better options than a Scalpel 29er frame IMO. Frames that are either slightly lighter in the same price bracket or of similar weights but at much lower prices. An extreme example is that some of the open mold weights are comparable in weight and that would let someone spend heaps more of a budget on other items. Also, there are lighter forks than a Lefty too (even ignoring something like a WR with toothpick sized stanchions). Unless you're getting a Lefty on a stock bike, they aren't cheap.

LAN wrote:If you want a light fs, consider buying a 26er Scalpel frame, and use 650b wheels.

If you're a smaller rider, this option, or even an older Spark with 650B wheels seem like fantastic options. It's a shame really that the Scalpel 29er isn't an upsized version of the old bike.

louwei0607
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by louwei0607

jooo wrote:I think skyfire1202 is still a member here. His bike 12.32lbs / 5.58kg

Image

Sure, some people wouldn't think Maxlites etc are daily riders but skyfire1202 still races his bikes. It's not like it would be heavy with with a SID, Crest wheelset, Racing Ralphs and Ashima rotors anyway.


WHAT A AMAZING BIKES. :thumbup:

01Erion
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by 01Erion

I must agree that we need to see more weight weenie MTB builds especially since mine is coming to a close soon. I, personally, would like to see more full suspension builds in particular, although that 5.5kg Scott rigid is pretty awesome.

bm0p700f
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by bm0p700f

That Scot is a throw back to ninties with small frames to save weight. What goes around come around eventually.

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tskubi
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by tskubi

Hi,
here is mine at 6,99

Image Image Image Image
Image Image


not a show bike, I use to ride it twice a week among 40/60km rides.

Full build here :
http://www.light-bikes.fr/phpBB/viewtopic.php?f=45&t=29
Enjoy your time under the sun.. and when its cold and dark don't worry too much, the world will keep spinning and your time in the sun will come again.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

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