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What is to Light?

PB Forum :: Downhill
What is to Light?
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flag Marc-91
Posted: Feb 16, 2008 at 10:32 Quote
mini-logo-888 wrote:
31 pounds would just be unsafe

it would be like 90 percent carbon fiber.

since when have carbon fibre products been unsafe?
high modulus carbon fibre is easily stronger than alu. alloys.
flag lelandjt
Posted: Feb 16, 2008 at 10:32 Quote
I think the original question was, "Is there a minimum weight, below which a DH bike loses stability or has other negative handling traits." This kid seems to know enough to stay away from parts that will break. For years general consensus was that weight didn't matter much for DH as long as it wasn't over 45 pounds because the weight helped stability. Recently people have been building lighter DH bikes and seeing the same improvements seen in other disciplines. I haven't heard anyone say that a 34lb DH bike feels worse than the same bike with 6 pounds of lead attached. I say go as light as your wallet allows while still thinking about strength and traction. (I love Maxxis 2.7 double ply tires)
flag Termenaitor
Posted: Feb 16, 2008 at 10:45 Quote
well go light on parts that dont really matter like seat/seat post bars and etc...but not on wheels, they have to be pretty strong.
flag boxxerman
Posted: Feb 16, 2008 at 11:04 Quote
Unless you really got a sh*tload of money from insurance, than you are better off building up a bike that weighs more like 36-39. It would be way more durable and nobody really needs a 31 pound Dh bike, unless you are really trying to make up for a lack of skill or strength.
flag calgaryrider
Posted: Feb 16, 2008 at 11:35 Quote
If you can get fifty percent off the demo, maybe try it out, with the savings you can spec it pretty crazy, and you'll have something different. Pretty much everybody and their grandmother rides a v10 in calgary, don't see as many demos around.
flag majordamage
Posted: Feb 16, 2008 at 11:39 Quote
i think keith bontrager said it best "light, cheep, and durable.....pick two"
flag Wilson4
Posted: Feb 16, 2008 at 12:28 Quote
What's with all this stuff and heavy wheels? Even if you have a heavy bike the best place to feel the loss of weight is through the wheels, tire, tubes combo. It doesnt help to have light bars, seat and seat post.
flag PedalUpBombDown
Posted: Feb 16, 2008 at 12:35 Quote
Wilson4 wrote:
What's with all this stuff and heavy wheels? Even if you have a heavy bike the best place to feel the loss of weight is through the wheels, tire, tubes combo. It doesnt help to have light bars, seat and seat post.
that's when I9 get's thrown into the mix. with the right hoops (823's) you can get a VERY light and very STRONG wheelset. going with Keith Bontrager's saying though, they won't be cheap.
flag Wilson4
Posted: Feb 16, 2008 at 12:42 Quote
Hate to say it the I9's are lighter and $300 cheaper than my 2350's.
flag PedalUpBombDown
Posted: Feb 16, 2008 at 12:44 Quote
Wilson4 wrote:
Hate to say it the I9's are lighter and $300 cheaper than my 2350's.
I9's hubs are sooo nice too. they go forever. no really, forever. there's a 29er I9 wheel on the trueing stand at my LBS, i spun it as fast as a could, went to my car, drove down the road, got a burger, drove back.....it was still spining. not very fast, but still going.
flag jallan
Posted: Feb 16, 2008 at 12:44 Quote
Full beam, i cant stand it when its left on to distract you from driving!
flag michael-scott
Posted: Feb 16, 2008 at 12:54 Quote
I don't think you really know what your getting yourself into here, to get a dh bike that light would take some serious $$$, way more then what your insurance company probably gave you for your glory. Plus the weight of it really isn't that important, I used to think it was but when I spent over two grand to get my bottlerocket from 42lbs down to around 36(and 4lbs lost were rotational weight)I hardly even noticed any difference when riding it at all, it was definitely a waste of money. And at around 36lbs I've already done almost everything I can to it without getting to crazy with my parts, to get it down to 31-14lbs like your hoping to do it would start getting very expensive and my bike would get much weaker.

The only real change that weight loss made was how often I had to maintain or replace my expensive and high maintenance parts. Like when I was in whistler last summer it was a disaster, every second run I had to walk my bike down the hill because my 590g tires sidewall got a tear in it or one of my other lightweight parts failed on me.


Here I found this on wikipedia under bicycle performance, it's for raod bikes but it's basicaly the same thing for dh-
bigquotesThere has been major corporate competition to lower the weight of racing bikes through the use of advanced materials and components. Additionally, advanced wheels are available with low-friction bearings and other features to lower resistance, however in measured tests these components have almost no effect on cycling performance. For instance, lowering a bike's weight by 1 lb, a major effort considering they may weigh less than 15 lb to start with, will have the same effect over a 40 km time trial as removing a protrusion into the air the size of a pencil

If you want to build a light bike go for it, you can build something around the 36-38lbs mark and still have it somewhat cost effective, but I wouldn't waste my time trying to build a sub 34lb wonder bike because it will never actualy be worth it.
flag Wilson4
Posted: Feb 16, 2008 at 13:09 Quote
s-t-e-v-e wrote:
I don't think you really know what your getting yourself into here, to get a dh bike that light would take some serious $$$, way more then what your insurance company probably gave you for your glory. Plus the weight of it really isn't that important, I used to think it was but when I spent over two grand to get my bottlerocket from 42lbs down to around 36(and 4lbs lost were rotational weight)I hardly even noticed any difference when riding it at all, it was definitely a waste of money. And at around 36lbs I've already done almost everything I can to it without getting to crazy with my parts, to get it down to 31-14lbs like your hoping to do it would start getting very expensive and my bike would get much weaker.

The only real change that weight loss made was how often I had to maintain or replace my expensive and high maintenance parts. Like when I was in whistler last summer it was a disaster, every second run I had to walk my bike down the hill because my 590g tires sidewall got a tear in it or one of my other lightweight parts failed on me.


Here I found this on wikipedia under bicycle performance, it's for raod bikes but it's basicaly the same thing for dh-
bigquotesThere has been major corporate competition to lower the weight of racing bikes through the use of advanced materials and components. Additionally, advanced wheels are available with low-friction bearings and other features to lower resistance, however in measured tests these components have almost no effect on cycling performance. For instance, lowering a bike's weight by 1 lb, a major effort considering they may weigh less than 15 lb to start with, will have the same effect over a 40 km time trial as removing a protrusion into the air the size of a pencil

If you want to build a light bike go for it, you can build something around the 36-38lbs mark and still have it somewhat cost effective, but I wouldn't waste my time trying to build a sub 34lb wonder bike because it will never actualy be worth it.

By the sounds of it he works at a shop, he mentioned he'd get almost half off on everything. Granted I can't say how much the insurance gave him it'll be a lot closer to $5,500 than $11,000. While I can't ague with what you felt with your bike I did notice a big change going from 41 to 36 pounds. Granted with tires that don't roll as well it's harder to feel the weight loss if your pedalling around. While your right as you get lighter reliability comes into question, using dh parts it isn't hard to have a light weight for $7,000 (yes that's a lot of money but its not much more than most top end bikes). 590 gram tires, you were totally asking for it. Though, I could be in the same boat with my single plys.

The wikipedia quote has nothing to do with dh bikes. We're the F1 cars they are Nascar. We have to brake and acclerate while they just stay at a higher speed. A lighter car accelerates, changes direction and brakes faster than a heavy one. Losing a pound on a dh bike is WAY easier than on a 13 pound road bike.
flag majordamage
Posted: Feb 16, 2008 at 13:39 Quote
I9's??? apparently I'm not up on the lingo???
flag majordamage
Posted: Feb 16, 2008 at 13:40 Quote
industry nine? I thought those were really expensive.

 


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