Paris Roubaix bikes

Discuss light weight issues concerning road bikes & parts.
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divve
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by divve

Dennis wrote:
7kg without wheels


He told today on Belgian television that his bike weighs 7 kg with wheels.


I know what he said. Doesn't mean it's true.

by Weenie


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Bruiser
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by Bruiser

asphaltdude wrote:Remember the old Trek STP frames? They don't have any pivots as well. The carbon fibre is enough flexible.
The Gary Fisher Sugar / Trek Fuel use flexible carbon too, instead of pivots. Cannondale Scalpel too.


Trek has just lost any image of their OLCV frames being stiff in my mind.

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BHobson
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by BHobson

Carbon, even though it is strong as hell, is also very flexible, but not so much to cause a problem. The suspension mod they use in that photo is a similar idea to Specialized's Zertz inserts,on their Roubaix and Tarmac frames. By cutting the carbon and replacing it with some sort of elastomer, you create a flex point in the frame, which is then supported by said elastomer. It is basically a passive suspension. So it doesnt mean the Treks are flexy frames. All carbon would work the same way if they were modified like that.
I ride a Roubaix, and its plenty stiff, and the inserts work like a charm.

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Bruiser
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by Bruiser

I've riden a cromo softtail which relied on the flex of the metal to make use of the 25mm of elstomer travel.

Arn't stiff and flexible directly opposing concepts?

burlguy
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by burlguy

10 years ago I worked at the local Lbs. I had seen softails and wanted to have one on the road . So around 5 years ago I cut into my steel road frame and brazed in a telescoping tube , just above the rear brake tube . I just cut two inches out of the seat stays. I brazed pivots in with brass bushings and used stainless hardware . I used an elastomer stack with adjustable preload, and a threadedrod running through the center length wise. This way I could keep it all tied together and tighten the rod with more elastomer in the telescoping enclosure to firm up the ride . I gave the bike to somone who needed it and he rode it locally for years. It did have more flex than I would have liked which made the rear wheel track not as well , but very comfy for riding around town . It had around an inch of travel.

I dont think I will do this to my Roubaix Comp though.

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the Repeater
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by the Repeater

Bruiser wrote:I've riden a cromo softtail which relied on the flex of the metal to make use of the 25mm of elstomer travel.

Arn't stiff and flexible directly opposing concepts?


A triangle doesn't retain it's strength or stiffness when you sever a corner.

I wouldn't be so much concerned w/ flex as a rigid setup, I'd be worried about torsional flex with the suspension installed. And flex and stiffness aren't really opposite properties for carbon fiber. I think this is most obvious in handlebars.

ShinyBaldy
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by ShinyBaldy

BHobson wrote:Carbon, even though it is strong as hell, is also very flexible, but not so much to cause a problem. The suspension mod they use in that photo is a similar idea to Specialized's Zertz inserts,on their Roubaix and Tarmac frames. By cutting the carbon and replacing it with some sort of elastomer, you create a flex point in the frame, which is then supported by said elastomer. It is basically a passive suspension. So it doesnt mean the Treks are flexy frames. All carbon would work the same way if they were modified like that.
I ride a Roubaix, and its plenty stiff, and the inserts work like a charm.


Trek just lifted their suspension mod from their Klein and Trek comfort bikes.... :)

ShinyBaldy
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by ShinyBaldy

the Repeater wrote:
Bruiser wrote:I've riden a cromo softtail which relied on the flex of the metal to make use of the 25mm of elstomer travel.

Arn't stiff and flexible directly opposing concepts?


And flex and stiffness aren't really opposite properties for carbon fiber. I think this is most obvious in handlebars.


the key concept is the direction of the flex. If you lay out more fibers at a higher density in one direction - you strengthen the structure in the parallel direction. Imagine a bamboo grown to adult size. You can tie it down by bending it on its horionztal axis perpendicular to the fibres (which orientated upwards mostly) - release it and it'll spring back. (FLEX)

Try doing the same from the vertical? *PUSH IT DOWN* - It won't budge. It is why in East Asia, we use bamboo to build the high raftings when building medium tall buildings. It is lighter, stronger and cheaper than say metal. It flexes in the wind (like a modern skyscrapper) - but won't break under reasonable load that a human with tools would place on it).

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divve
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by divve

I don't know about the other riders, but Hincapie wasn't using it.

ShinyBaldy
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by ShinyBaldy

divve wrote:I don't know about the other riders, but Hincapie wasn't using it.


http://www.cyclingnews.com/photos/2005/ ... e/L1000213

they had it in that foto with his name on it? Were you able to watch the back of frame during the coverage? The rest of the frame looks exactly like a 5000/5200/5500

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divve
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by divve

Yes, you could see his back a million times on TV :)

ShinyBaldy
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by ShinyBaldy

divve wrote:Yes, you could see his back a million times on TV :)


Roger Hammond and Roberto Petito seems to have used them... hmmm looking at the pictures of Hincapie's bike... it looks like a 5000/5200/5500 design and the seatstays ... it looks like he did use them... (the actual unit is hidden in the pictures I'm looking at) - but the seatstays can be clearly seen to be curved (and it also turns out that the new modifications utilize curved seatstays not generally found on the madone or 5500 series...)

*shrug* ah well - whether he used him or not doesn't matter ;) I'm never gona buy one. *have a section of 500 meters of cobbles in town - and that'll shake your components apart because they're not even filled in properly so I'm not going to go ride 20mph through them.

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divve
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by divve

I should have taped it so I could check it again.

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asphaltdude
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by asphaltdude

Hincapie DID use a frame with rear suspension.
Whow! That's a pretty damn nice garage door!

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Frankie - B
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by Frankie - B

BTW, very funny pic...

Image
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'

by Weenie


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