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Discussion in 'Downhill & Freeride' started by Cyklist, Apr 4, 2010.
Awesome bike! Looking forward to a ride review....
I bet this bike will fly down the trail.
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Physics does not agree with you. Find a race discipline (with both turning and stopping involved) where less weight is not a goal. Reliability is really the only thing that puts a lower limit on weight, and riding smooth helps keep that number lower.
I'd rock a sub 30lb 8" travel dh bike if the geo worked for me and it stayed in one piece.
I agree to an extent but I had a V10 around 35lbs and it rode great.
why? with loctite on them, they are no different
He must prefer running 3 steel bolts instead
Agreed. People would just need to set their suspension up totally differently for a bike like this, and it would feel different. Which people would automatically equate with "unstable" but would probably not be true (I think). The bike might have a higher COG with a rider on it though, so THAT mike make it more unstable? I'm just guessing here though.
That's because you set it up, well, really soft. For fast rough stuff (especially if its steep) you want it set up stiff. Or at the very least, a stiff fork. Undersprung forks seem to be the number 1 cause of a bike feeling unstable at in fast/rough stuff IME. They sit too low in the travel, and dive a lot more. I've done a lot of experimenting with my 66 ata lately and the change in how fast I can comfortably ride when I go from like 70-80 psi to 100ish is actualy quite noticeable. Again, especially if its steep, or in rock chutes.
Your mileage may very, but that's what I've found.
So my bike should be 80 lbs as Im 230!
What are you talking about 2/3rds LOL I must have missed the weight ratio in the general riding manuals and overall DH build etiqute handbook... LOL
As far as tracking are you kidding LOL the lighter the bike the MORE it will go of its path when it hits an object and is deflected or in the rocks it will be chattering all over the place like OS tires that are rock hard. Too light is definently possible without question, our sport requires some mass to help the bikes stability and path. A heavier object will command its path as where a lighter one deflects off stuff....
Play pinball with a ping pong ball and watch the ball get knocked all over now play with a bowling ball and watch the flippers get plowed over!
woah, nice reaction there guy. I got the ratio a bit off there but i suck at the sciences.
-edit- I still think it would be just as easy to handle only different. Putting another wheel set or a different crankset on this bike and it would be maybe 3 lbs heavier everyone would be all about it. Having started the 40lb bike thread you should be stoked.
I had a 35lb bike and yes it held up to abuse and was reliable BUT it got bounced all over on nastier terrain and rock chutes to the point it wasnt worth it.37-38 for me is right in the sweet spot.
As far as the reaction it caught me off guar I almost choaked on my food when I read it and laughed. So I wasnt beign an ass it was just really odd to read that. But I heard it was 1/2 your left thigh weight for every foot of wheelbase, but Im just guessing here!
No offense man just found it funny!
Yeah 40 was good and it helped out alot of people to shed weight and bring the bikes down a bit. I got hooked on super light last season and this seaon Ill be sticking with a tried and true weight which is between 37-38 for me.
There are courses Ill rock 36 but 95% will be higher as it reacts better...
I'm sure you are on to something, there must be some reason that on most of the wc tracks all of the heavy hitters are running bikes in that 17-18kg range.
Yep, like riding it off road. We all though the 951 pics looked pretty bad, wait until these things start snapping left & right.
I plead stupidity and dont want to be on to something, If I have a normal thought and the wife finds out Im screwed Ill be expected to do stuff!
No when I did MX I had lighter bikes for play and when it came time to hammer parker az and a few other areas high speed I prefered a bike with heft I had less fatigue as the bike didnt deflect off crap all the time and I could focus on staying the course vs trying to stay on the course.
BUT there are guys that on some courses can rock that build, I gove him total credit for hitting that weight as its insane and congrats!
And a 35lb v-10 for you thats a hell of an accomlishment so congrats on that...
The only thing that would make a bike deflect would be lack of structural integrity. ie: the parts you were using weren't strong enough for you. Extra weight at equal strength only causes additional fatigue.
Really! I dont think deflection has anything to do with structural integrity directly, as its a motion caused by an action or ie newtons law for every action theres an opposite and equal reaction. A lighter object will infact have more movement as it takes less to get it moving = more rider correction to compensate!
A heavy car plows into something it has a tendancy to stay the course a smart car hits something and it goes whichever direction has the path of least resistance and then theres no uniformity to it as its going where the hit puts it.
Point in case my old 4k lb 7u desert truck didnt get hammered around like a class 3 buggy that was lighter and softer suspension in the rough.
Theres a definent realtion between weight and path.
Ya, it's because they'd destroy lighter bikes, even before they're done with one run. People always seem to underestimate how brutally punishing on the bike that one run of saw Mt. Sainte Anne would be under rennie or kovarik or Hannah or someone like that.
amazing build & fantastic proof of concept. not for everyone, but i've no doubt that would be a reliable race rig under a non hackish / clydesdale rider. i remember back in the tank bike days when sub 40 was deemed sketchy by some. now, mid 30's is commonplace. quite the progression. would love to see a ride review.
I have a Trek Fuel EX 8 that weighs in at just over 28 lbs.
A DH bike just under 30 is nuts.
In the article below Cam McRae said his fastest laps were on the 33 lb Session Trek built for demo/show.
Thats a good write up Im impressed with the complete coverage!
Love the looks of that bike, and thats a pretty sick build!
Really nice build!
Ok, so if the rider is a light guy at about 70 kg the weight drop from a 15,5 kg to a 13,5 kg bike is 2,4 % for the whole moving object. That is not much! I do not see how you have to adjust the suspension in a totally very big awesome way?
At the same time the bike part of the weight is just 16-18 % of the weight, your body carries most momentum anyway.
Yes, granted that there is the possibility that the bike will be a bit livelier on the trail, but then you as a rider simply have to adjust to this characteristic. The liveliness also means it is easier to put the bike where you want it so it is a coin with two sides as always.
All in all I think there are more advantages than disadvantages with a light bike. This build will probably hold up for most of the riding it will see.
Just plain awesome.
May I do a lap or two at Gesunda with it? I'll bring my own broom.
Christ! Thats lighter than my XC bike!
Thanks for all the nice comments!
As for the know-it-all or maybe not so well thought thru comments - thanks! I knew I'd laugh my ass off when I'd read this thread!
So just to give you guys a little perspective. You don't know anything about my weight, how smooth or fast I am, riding style, am I racing or what style of riding I think is the most fun way to get down that mountain.
Because surely you must, if you stop and think about it, realize that I built this bike for me and only me.
And second of all 99% of you haven't spent much time on a downhill bike below 35. I on the other hand rode a 32,25lbs Session all of last summer, so it's not like I'm jumping from 40 down to this.
So how does a bike that light ride then?
It's a blast, so damn much fun. Many of you seem to think less weight/"stability" is always a bad thing. Sure in some sections it might be a little bit faster with a bike that carried a bit more momentum (more on that later) but on all the other sections.. I can stop on a dime, I can litterary move the bike around to get into any line I want, I can turn it sideways on the smallest of jumps and I can snap out of corners like a piece of cake.
Just like you adapt your style, skill and technique when riding a new bike with different suspension or geometry you adapt yourself to riding a bike this light too. It's a bit like going from hiking boots to some light trail running shoes. Suddenly you can jump between rocks that you couldn't before and take different lines.
For those of you who think it'll feel a lot like your equally light AM bike of course it doesn't. I think we all know how much difference there is in geo and having 8" of travel instead of 6", so no I won't get a 20lbs xc bike as someone quite seriously suggested.
It's not for everyone, but I love it. And when it comes to riding freeride stuff like bc-jumps or a-line-style tracks imagine how fun it must be with a bike with downhill geo that you can really push but it's light like a 4X/DJ bike when it comes to the jumps.
Now over to momentum/deflection and all that. Most of you seem to forget that what changes the feeling of the bike the most except for suspension setup wouldn't be filling the frame with 5lbs of led but what tire setup you rock. The noticable difference in carrying speed when really plowing through a rock guarden has more to do with the rotational mass than equal mass anywhere else on the bike.
For example, say that I'd put on some Der Kaisers or heavy Schwalbes along with some really chunky dh tubes and this would add around 2lbs. This would change the characteristics of the bike so much more than putting on a drivetrain 2lbs heavier.
Good thing is that if I want to one day I can easily do that and still have a pretty light and really fun/fast bike thanks to the bike being so light anyway. The higher rotational momentum of the wheels would make the bike a lot more stable and plowing-friendly (or heavy and dull depending on how you see it). You'd ride a bit more like a monstertruck driver than like a ninja.
To me riding is all about having fun and the bike building itself is just a nice hobby to have during the long winter.
So if any of you spot me on some hill don't hesitate to say hi and maybe you could try the bike out.
And as for the narrow minded ****heads - thanks once again for the laughs.
Good job cyklist
Now i know why they call it wight weenies, cause they ween alot ....
karpi: I'll see if I get the time to weigh it later this week, I'll send you a pm.
Jon: Thanks, and I'm sorry I left out the 14 gram cs protector.
Mårten: Sure thing!
Gary: I simply shaved some weight off the LG1+, same thing with the shifter and I also made the derraileur a shortcage. Here's a few pics for you (alu/ti bolts missing in the last two pics).
Is the rear mech now lighter then if you would have used the cage of a Saint short mech(What I did)?
And ckeep an eye out on the axle of the XTR Crankset, a friend of mine broke the axle on a drop into 4 pieces (had them fitted to a sunday)
as much as the build does look (surprisingly) good, i'd be worried about running no bashguard and very little metal on the chaindevice - basically 1 rocky run and that could ruin your day
WOW - I have an 09 and it's coming in at 36lbs..... that's a sick setup!! Good job
This is so awesome. You know that guy your riding buddies friend read about online who has a really awesome and light bike? This is lighter...
That thing wouldn't make it down a run with me on it. Plain and simple. Doesn't mean you can't ride it a whole season with zero troubles.
I also have no doubt that the first time it ever has any sort of mechanical, a crowd will gather en masse to lynch you and berate the bike.
Yup, this is true. My experience could be a combination of different things and also rider preference. It is somewhat counter intuitive. One would think a lighter bike is easier to manage and some cases it is (or for some people it is). I just never felt stable at high speeds and in the rough. I also felt that braking was less controlled as I tended to skid or bounce around a bit more. I could probably learn how to ride it better just as I have learned how to turn and jump a heavier bike. That is also why I mentioned that one major exception in my previous note: My skillz.
BTW, I am not trying to hate on the bike, this is just my perception based on my own personal preferences. I think it is great to see people take things to the extreme and share it with the rest of us.
Perhaps I missed it but how did you get the XTR cranks to fit?
When do you strip the paint and decals off? That's gotta be a quarter pound right there.
Because Ti bolts under shear force is a huge no no. Its not a function of adding loctite, but understanding material properties.
Honestly, I could care less how light someones bike is, but for those pushing the limit, please don't blindly add lighter components or fasteners without fully understanding how they mechanically function.
I don't know if the OP is still reading this thread, but for your safety I would strongly recommend going to normal torx bolts on your rotors, and would also recommend the same for your stem to crown bolts which also experience cyclic shear loads.
so since Marzocchi sold me a fork with Ti hardware, then i should be in trouble and possibly looking at a lawsuit against them?
i've been using ti rotor bolts for years, w/ no issues. got a couple sets of the stock avid ti bolts currently; you think they'd supply them if there were any shear concerns?
To Inclag and OP: Ti bolts will be just fine on your rotors. I don't want to argue with you Inclag, and I have no point in saying this other than just to set the record straight in case anyone else is worried about their bike. And if you want to ask for references fine... I can PM them to you.
Sweet thanks! How did you cut your shifter? Did u just use a dremel? or do those come like that? What about the wholes on the chain guide? Its real cool that you took the next step forward into modifing the pieces on your bike, a couple of grams here and there add up. Have you though about putting some holes on the seat tube? that works too. I think I've seen some lighter pedals around, don't the Ultra Mags weigh like 320? There were a couple that went down to 250 or so (crazy light). Last but not least, what about stripping the paint? I dont think that trek has very think paint anyways, but wouldnt it at leas save you a 150-300 hundred grams? It reminds me of the 14 kg Session 88 trek build when they launched the bike, Nico Vinks bike...
almost forgot, what about using Formula The Ones, they are lighter and brake a lot harder!
JD at MSA with Ti stem bolts...