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Discussion Starter · #1 ·
If Colnago makes no curved steel forks, what is the advantage of their straight steel fork? I have a Surly curved steel fork on my Classic now. It rides fine, but looks funny if not sacriligious.
 

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colnagophiliac
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colnrly said:
If Colnago makes no curved steel forks, what is the advantage of their straight steel fork? I have a Surly curved steel fork on my Classic now. It rides fine, but looks funny if not sacriligious.
Physical properties of carbon fibre: Fibre direction is same in a "straight" fork ie axial resistance to road shock. A steel fork will also resist shock but by flex. (hence my reference to Hetchins earlier - "curly" stays etc.) Ernesto won't like flex - it isn't always in the advantageous direction - dissipates energy etc. Hence "stiff" frames. All my steel frame bikes ( except my MXL) have curved forks - three Colnagos, Merckx, Hetchins etc. They're lovely. My MXL has a straight steel fork. It's lovely too. All great bikes are brilliant.
 

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colnagophiliac
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edmundjaques said:
Physical properties of carbon fibre: Fibre direction is same in a "straight" fork ie axial resistance to road shock. A steel fork will also resist shock but by flex. (hence my reference to Hetchins earlier - "curly" stays etc.) Ernesto won't like flex - it isn't always in the advantageous direction - dissipates energy etc. Hence "stiff" frames. All my steel frame bikes ( except my MXL) have curved forks - three Colnagos, Merckx, Hetchins etc. They're lovely. My MXL has a straight steel fork. It's lovely too. All great bikes are brilliant.
I'm going mad here - replying to myself. Having read my first reply I realise I didn't answer the question posed. So...... A straight steel fork is stiffer than an otherwise similar curved one - less opportunity to flex. My MXL (straight) does feel stiffer than my other curved fork bikes, but it does have the advantage of being further down the evolutionary chain ( so to speak) Frankly, anything Ernesto makes is OK by me - I'll probably let him off anything.
 

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ed,
actually, a curved fork, or any "coldworked" bent tube may well be "stiffer" as it is work-hardened and therefore less flexible, ernesto would probably argue the straight blades absorb vibration throughout the length of the tube more effectively as well as a result.

this miniscule difference is probably second to the desire to offer a a radical departure from
the norm, an agressive appearance that is appealing from a marketing sense, to keep desogn appearances moving forward...
 

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Discussion Starter · #5 ·
BUt does it affect the handling?

edmundjaques said:
I'm going mad here - replying to myself. Having read my first reply I realise I didn't answer the question posed. So...... A straight steel fork is stiffer than an otherwise similar curved one - less opportunity to flex. My MXL (straight) does feel stiffer than my other curved fork bikes, but it does have the advantage of being further down the evolutionary chain ( so to speak) Frankly, anything Ernesto makes is OK by me - I'll probably let him off anything.
I have heard that the straight blade fork will make the handling "twitchy." It had the straight carbon fork when I test rode it and I can't really tell the difference. BTW, will I be kicked out of the Colnago club for putting the Surly fork, Nashbar pump and TruVativ cranks on it?
 

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twitchy?, nah, not necessarily, the straight fork still has the rake (43) currently specd by colnago, lotsa people think straight means more upright but the rake is still there, originating from the fork crown.

as for the other, if you got it on the road good for you!



colnrly said:
I have heard that the straight blade fork will make the handling "twitchy." It had the straight carbon fork when I test rode it and I can't really tell the difference. BTW, will I be kicked out of the Colnago club for putting the Surly fork, Nashbar pump and TruVativ cranks on it?
 

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Discussion Starter · #7 ·
So what does rake mean in layman's non-technical terms?

odeum said:
twitchy?, nah, not necessarily, the straight fork still has the rake (43) currently specd by colnago, lotsa people think straight means more upright but the rake is still there, originating from the fork crown.

as for the other, if you got it on the road good for you!
I looked it up but...
 

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colnagophiliac
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colnrly said:
I looked it up but...
Couple of things: Banging in a straight nail is reasonably straightforward. The same nail a bit bent - tricky. There is axial force deflection. This might be OK for dissipating road shock but it works the other way round too - wasting forward thrust. There is an article in "Master Mag" year 2000 - I don't know if it got to the US ( I'm posting from the UK)- but it is a Micky Mouse dissertation on force wasting in bikes. Pretty basic physics but plausible enough to me, enough when I'm out on the bike anyway.
 

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When I bought my Colnago, the dealer (a true Colnago fan) told me pretty much what edmundjaques says a couple of posts above. He told me (and he also showed me in a demo) that a straight fork, when confronted by a bump in the road, tends to want to jump forward, while a curved fork tends to want to jump backward. Thus, the straight fork makes you faster! Smiley Face. Smiley Face. Smiley Face.
 

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l'illustre sconosciuto
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ultimobici said:
How so? They still require the same accuracy to ensure the fork behaves correctly. Ask any framebuilder.
The manufacturer either buys straight blades and curves them (hence an extra production stage), or they buy the blades pre-curved (hence an extra step for the tubing maker and subsequent extra cost to framebuilder). Furthermore, the joint of fork blade to the fork crown is by the far the easiest to miter of any on a bike when you use a straight blade.
 

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Interesting discussion.

Didn't the Colnago curved forks preceed the Precisia Steel straight forks in production?

I don't race so when I've built my framesets, I've just made sure the correct era fork was on the correct frameset. I figured they made it that way for a reason when it was manufactured. I just acquired this and installed it on a 92 Sprint Super.
 

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colnagophiliac
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Yes: Curved (Colnago) forks preceeded straight ones. Cut off date mid '80's. I have several curved and straight forked Colnagos, I would guess the geometry would have changed according to the fork somewhere in all the measurements. One day, being a particularly sad person, I'll measure everything. The straight ones ride better but they're lighter and have more modern components - brakes inspire more confidence etc. so the comparison is meaningless. They're all brilliant.
 

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couple quick notes

vibration is energy. energy travels more effectively in a straight line. a curved fork actually has the ability to 'sluff off' some of that energy plus having the potential ability for a slight 'spring effect'. Straight fork is stiffer and cheaper to make. In most cases fashion is sold to cover nothing more than cost savings for the mfr. hence the decline of lugged steel.
 

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dnalsaam said:
The manufacturer either buys straight blades and curves them (hence an extra production stage), or they buy the blades pre-curved (hence an extra step for the tubing maker and subsequent extra cost to framebuilder). Furthermore, the joint of fork blade to the fork crown is by the far the easiest to miter of any on a bike when you use a straight blade.
It's not the mitreing that is hard, it's getting the dropouts parallell etc with the effects of heat on an unsupported joint.
 

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atpjunkie said:
vibration is energy. energy travels more effectively in a straight line. a curved fork actually has the ability to 'sluff off' some of that energy plus having the potential ability for a slight 'spring effect'. Straight fork is stiffer and cheaper to make. In most cases fashion is sold to cover nothing more than cost savings for the mfr. hence the decline of lugged steel.
Building the straight fork required new dropouts and head lug, as well as new jigs, negating any short term labour cost savings.
The "spring effect" of a metal structure is beyond minimal when it is attached to a wheel with a tire inflated with air.
 

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straight forks look cool.
 

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In 1986 Colnago started colaboration with Ferrari and it was one of their designers that questioned the commonly accepted phenomina that curved blades have better absorbtion qualities than a str8 fork, in his opinion a str8 fork would be just as good if not better. What makes a huge difference is the ride characteristic, str8 forks provided a sharper handling and responsiveness. So in actual fact the idea for a str8 blade fork came from Ferrari and in 1987 Colnago made the first str8 steel fork.
 
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