Steel, Titanium or Carbon frame?

Discuss light weight issues concerning mountain bikes & parts.

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stephen@fibre-lyte
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by stephen@fibre-lyte

TheRookie wrote:Trek offer one of the best frame warranties available, they could bankrupt themselves if they produced shoddy frames, clearly a hand made frame can be good or really bad, I didn't say the trek frame would be Better though if you read what I put.....

The Treks and others use prepreg and an expensive mould, you could never have that with a one-off frame as the moulds are circa £5k each, plus going mass produced you have time and budget to do development builds and testing......


When you say 'one of the best warranties available' what do you mean? Do they honour every claim or...?

The reason why mass produced frames use an expensive mould is repeatability. The moulds could be made far cheaper for a one off. For example, our special projects engineer has built one time trial bike and two mountain bikes exactly how he wanted them and for far cheaper than he could buy a good carbon hardtail.

With mass produce frames you also have to bear in mind that efficiency is key, low cost manufacturing is paramount. With hand made frames, time can be taken and the budget is only limited by the customer.

TheRookie wrote:But there is no reason for a carbon frame to be stiff, it can be made just as supple as any steel if that is what the maker wants, also as it has the highest internal hysteresis it's the best damped.....


very true, but the problem is how many manufacturers can you name that produce their own carbon tubes for frame building? There are more options available for alloys than there are for custom carbon.

TheRookie
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by TheRookie

stephen@fibre-lyte wrote:very true, but the problem is how many manufacturers can you name that produce their own carbon tubes for frame building? There are more options available for alloys than there are for custom carbon.

I wouldn't buy a carbon frame made from tube, only a true monocoque...

The Trek Superfly has an obvious soft feel in the vertical direction, without feeling at all soft in the longitudinal.
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stephen@fibre-lyte
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by stephen@fibre-lyte

Interesting comment. Why not? Probably the most well known high end carbon frames in the world (Colnago) have been manufactured from tubing for years.

True monocoque frames are very few and far between. they're usually sectional frames bonded together. I think you're also imagining that a monocoque frame will have all the fibres laminated in the direction that they're most required. It's a nice theory......

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by TheRookie

Tubing was fine from the start, it only moved on from the tubing between metal end sections, but most the the MTB frames (this being an MTB forum) at the higher end are monocoque, such as the Scotts and Treks.
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stephen@fibre-lyte
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by stephen@fibre-lyte

Why was tubing only fine 'from the start'. Tubed carbon frames still make for some very nice bikes. In fact, most frames still probably are, they just subtley hide it.

Where do you get your information about the frames? There's no mention that i can see on either Trek or Scotts website about the frames being moncoque and last year (I think) I saw pictures of the manufacture of a Scott Scale and it certainly wasn't monocoque.

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by TheRookie

Tubing was Ok when CF was a developing technology, we've moved on.

Some of the Scotts are definately monocoque, the latest treks likewise - based on the technical reviews where they discuss things like the numbers of bladders used, in fact the 1990's Trek y was as you couldn't have made that out of tube!
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stephen@fibre-lyte
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by stephen@fibre-lyte

Sorry to tell you this but carbon tubing is still widely used, we haven't 'moved on'. Of course, there are other methods of moulding carbon. Bladders can be used anywhere that you want internal pressure to press carbon against an external mould. That doesn't necessarily mean monooque. Many moulded and shaped frames that aren't made from tubing are usually made from at least three separate pieces moulded individually then bonded together. Monocoque suggests a one piece construction.

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by TheRookie

OK, I accept that making sections and bonding isn't true monocoque, but on that basis no car is a monocoque either and I think that's a somewhat pedantic detail, but that's very different from gluing a bunch of tubes and then having a single layer of outer wrap!

Tubes correctly integrated can become part of a monocoque anyway, emphasis on correctly of course.
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stephen@fibre-lyte
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by stephen@fibre-lyte

All I was trying to get across was there's no reason to judge a bike based on whether it uses tubes or moułded sections. You stated that you would never buy a frame made from tubes, only a monocoque. Now you're saying they could be one and the same :wink:

Back to the material choices, Columbus xcr steel seems to be a popular steel frame choice in the us yet my local frame builder has said that as far as he's aware it's a road tube set. Anyone know Amy different?

ticou
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by ticou

I'm pretty sure I've seen one on one of the NAHBBS vids on youtube this year or last..could be IF.

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by jooo

TheRookie wrote:that's very different from gluing a bunch of tubes and then having a single layer of outer wrap!

Wow TheRookie - what fantastic knowledge you have of tube to tube construction :roll:

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by whodesigns

By definition a tubular based structure is not a monocoque, none of the so called "monocoques" are anything close to a real monocoque.

All the frames that I have sectioned are based on an assembly of pieces bonded or wrapped together.
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andy2
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by andy2

Most so called 'monocoque' frames have a segmented and bonded main structure. Some frames are marketed as monocoque but are really joined tubes at nodes.. Our Rolo main frame is a true monocoque with the chainstays/seatstays bonded.
If you are a light guy, say 70kg or lower, I feel you are best served with a highly reduced tube fillet braced steel bike!
(Why not carbon you ask? The answer is carbon manufacturers do not adapt the layup schedule to size. The smaller the size the stiffer the frame were it really should be the other way around.)
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by thisisatest

More companies are starting to adjust layups, overall dimensions, even lower headset bearing size, according to the size of bike. I feel this trend will really take hold.

by Weenie


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stephen@fibre-lyte
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by stephen@fibre-lyte

andy2 wrote:If you are a light guy, say 70kg or lower, I feel you are best served with a highly reduced tube fillet braced steel bike!


78kg at the moment Andy :oops:

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