Jseis 

After putting about 4,000 miles on my soon to be classic Colnago Dream Lux in the last 18 months and enjoying the stiff frame and sweet handling...and thinking about which way to restore my long in the tooth Grand Jubilee I got to thinking about S. Brown's comments about improving handling on old French classics by swapping out the old-school swept forks for modern straight forks. My G.J. is somewhat complicated by the need of a fork with cantilever bosses. Here's the question; Assuming (maybe?) complete headset replacement if necessary (the Stronglight Comp headset is well aged), could a 1" threaded CF fork offer significant handling improvements? I've just started googling and 1" threaded CF forks with canti bosses are available. Anybody done this type of swap?

As I recall, the GJ has somewhat shorter chain-stays. I'd predict the ride would be a bit stiffer, a bit tighter & quicker with more precise steering. The current GJ fork is nothing special; Not 531 & heavy, chrome, and well swept. Regarding the headset..I'd imagine the installation of a new headset might require upper and lower bearing race machining for the press fit to the French tubing diameter headset?

An original resto is easy, I want a sweet looking classic that I can ride, handles well, turns a few heads and will go another 40 years (keeristo...I'll be 98 in 40!).

fender1

I would take the time, money and energy and put it into getting a different bike.

Chombi

No, No, No,....Nooooooooo!

unworthy1

I can't imagine that a "modern straight" CF fork is the right course to take to get that "sweet-looking classic".
It might turn a few heads, but they will be shaking in disbelief.

To each his own: I have certainly tried a few things like CF and threadless forks on otherwise classic steel frames, I'm no purist. So, far I've always gone back to the original forks and been happier.

As to the HS: the cups for a 1" HS should fit a French frame's head tube with no machining required. The crown race will need to match (27.0 or 26.4) as will the threading of the top race/cup and lock nut (FR or ISO threading) to the fork…but chances are you'll only have ISO threading on any modern 1" CF fork.
Don't buy a cheap CF fork, been there done that. You get what you pay for with these products.

3alarmer 

...I think maybe Sheldon and I have different ideas on what constitutes "improved handling."

The handling will certainly be quicker, but if you want quicker handling, you probably also want a
shorter wheelbase and steeper angles. And yeah, there's no way I would consider doing this,
and I can get CF forks pretty cheaply at the co-op here as cast offs and take offs.

It won't look sweet, it will look way stupid, and the heads that turn will be in disbelief.

Edit: nice troll...it took me a minute, but you gave it up with "sweet."

Barrettscv 

Does a threaded 1" carbon fork with cantilever posts even exist? What are the rake and crown-to-axle specs?

RFC

Actually, this may not be a bad idea. I have put carbon forks on several C&V and was pleased with the outcome. To tell a secret, I don't think the majority of C&V forks I've ridden are really very good. With the worst of the bunch, there is sort of a "boing boing" bounce to them that is kind of annoying and adds nothing to the ride. Of course CF forks come in different levels of stiffness. I know that Nashbar has a 1" CX fork with cantilever bosses.

Barrettscv 

Yes, a threadless fork. A threaded CF 1" CX fork probably doesn't exist. Heck, the few threaded 1" steel CX fork sold are mostly used or NOS.

spacemanz

I bought a 1" CF road fork (no bosses) from Performance before, but it was threadless, and was for a Cannondale, which would be vintage aluminum, so kinda appropriate, I thought. Unfortunately, that old bike was destroyed by a careless driver, while locked to a phone pole support, LOL. I've thought hard about trying that fork on other bikes, like maybe the Columbus SL Miele, which has issues with forks anyways. One of these days, I'll think to grab a 1" threadless headset again, & investigate this further.

Lascauxcaveman 

I like the idea of trying a CF fork on a frankenproject; say a flourescent green spraybombed single speed, but a Grand Jubilee? Give me that swoopy curved French steel fork every time. Classic. (And I like the way those things ride; I'm not racing on a bike like that anyway.)

Jseis 

'bout the responses I expected. Resto v. Restomod. I've been investigating the Nashbar (spaced on the threadless aspect). I'm no purist as 1/2 of the GJ's original parts were long ago swapped out when it was just another mid-grade touring bike: TTT stem, Avocet (Omfega) hubs, Time pedals, Super Champion rims with SS spokes, Suntour bar ends, MaFac cantis, etc. Original derailleurs though (it is a Grand Jubilee!), Weinmann levers and Pivo bars, 49D crankset, Ideale Record 80 saddle).

@24 pounds it was considered a "light" touring bike. I consider the front fork/headset combo dangerous as braking on irregular road surfaces from speed 20+ as waaaay to much noodling going on. There's a good and downside to a flexy ride. A black CF fork would complement the red with black accent and gold pinstripe paint and with spit polish chrome & SS & aluminum..it would look damned sharp and be ....a safer ride.

fender1

Just sell it and get a used racing bike. It will never be a racing bike, no matter how many mods you make to it. It has value as it stands and you can capture that value and transfer it to another bike that better meets your needs. Upgrade-itis comes in many forms and trying to change the nature of what something is vs. what you want it to be, is a waste of time and money IMHO.

Barrettscv 

I've had both steel and carbon fiber Cyclocross forks on my steel and carbon fiber Cyclocross bikes.

A modern steel CX fork is a big improvement in terms of performance over most most forks produced in the 70's and 80's.

A good modern steel CX fork is also an equal to most carbon fiber forks. Most carbon fiber forks are mostly nothing more than an aluminum fork wrapped in carbon fiber. The aluminum structure includes the steerer, the crown and the upper half of the legs. The weight savings of the carbon fiber fork is often less than expected.

I have a full carbon fiber fork, with a carbon fiber steerer, on my carbon CX bike. That fork is light and performs great. I also had an aluminum & carbon fork on my steel Soma Double Cross. That was a good combination but a steel fork would have been just as good. I also have a steel Surly fork on a modern steel cyclocross bike, that is a good fork, as good as the aluminum & carbon fork on my Soma.

All of these forks are an improvement over most vintage forks. But giving up the threaded steerer vintage OE fork and using a 1" threadless steerer modern is a big change, due to the change to a new headset and stem.

Chombi

Do what you want to it, it could be an interesting and maybe even rewarding experiment,...... but please do not lose, give away or sell off the original steel fork in the process.....

Jseis 

That might be a really good idea. I certainly don't race the GJ but I've ridden it fast down hill enough to know the limits of the original fork and swept forks do make for vintage handling and that's just that...lousy in the steering and flex department. A "buttery smooth ride" comes with quirky handling. I've most the original parts ('a potato'd bent front wheel not worth straighting...bent at butt) but I'm no resto geek. A fine sweet ride in the 12-15 mph range. And as noted above...I'm not tossing parts.

repechage

I think there is something else going on to cause you discomfort.

Most CF forks will not be of similar, length / rake. The bike will most probably handle differently. How it ends up? I do not know.

bloom87

here are pics of a classic steel 80es bike w/ a carbon fork

ride was, to be honest (tho i'm not a carbon fan) fantastic.
i encourage to go the unorthodox way. there is a lot of satisfaction to be had, contrary to what a lot people on this forums say...

afilado

I installed a 1" threaded carbon fork on high-class steel mid '60s Belgian fillet-brazed frame and it became my favorite rider. The Frankenbike image disappeared in the sheer pleasure of the ride.

J

unworthy1

well note that this is a Kestrel (made for Litespeed) CF fork, which is a high-quality fork…that's what you want to buy if you go this route. Compared to the cheep Chi-wanese stuff you might get from some mail-order shop (no names, please!) there is no comparison.
Also note that this bike has Biopace rings…'nuff said!

SuperLJ

I don't know what the head angle on your Moto might be, or what the rake is on the cf fork you're thinking of tossing on there is, but I can tell you don't either, and that scares me.

If the current steel fork has a lot of rake, it's because the bike the bike has a slack head angle, and in order to arrive at a proper trail figure, that's what the designer specified. Designers weren't taking a stab in the dark back then - they knew exactly what they were doing. In many ways they were far more enlightened than the people who design bikes today.

Put a fork with very little rake on a bike with a slack head angle and you'll possibly end up with a trail figure way up over 70mm. Good luck cornering fast with that. Slow down, leave youself LOTS of extra room to get around, and make sure there aren't any cars in the oncoming lane!

If you're having handling and braking issues with your current setup, I don't think the problem is your steel fork, unless it's bent or damaged in some way. BTW, a "buttery smooth ride" and "quirky handling" have absolutely nothing to do with each other.

Jseis 

Without knowing the builders specs, nor having measured nor calculated the frame differences between the GJ and the Dream (something I should do just for my own interest) I sat them next to each other last summer and compared their frames, head tubes, etc. I was surprised how similar they are knowing that the designers/builders goals were vastly different. I would say overall the biggest difference in the Dream is weight forward (shorter top tube), frame and fork stiffness. The GJ is weight slightly back (longer top tube) frame flex and fork flex. As I recall, the seat tube of the GJ is laid back ever so slightly compared to the Dream.

The Dream is absolutely sure footed cornering particularly at speed and the GJ isn't. After riding the Dream for thousands of miles then switching back and forth between the GJ (and Centurion for that matter) I began to see why S. Brown's comment regarding swapping out old school flexy front swept forks with more modern forks (stiffer) can make an older bike handle better. Would I notice the rake/trail difference? Probably not because the differences in wheel base, weight positioning, frame flex will still be the major differences. When I retire one of my bucket list items is to take that frame building course held way south (Ashland I think?). It appears that such a fork swap is done, those that have done it notice improvements.

FYI..my exposure to the inherent hazards of a flexy frame began with descending Sunwapta Pass on the GJ while touring..fully loaded, at speed, braking (in 1976, I'm an older dude). I was astounded by the frame flex as I watched the forks load and flex, then the vibration of the road surface translated into the stem noticeably moving fore and aft. Last time I ever took the GJ over 25 mph (loaded or unloaded). I get the comfort argument, the "buttery soft feel of steel", etc. etc. but for my everyday riding which is relatively speedy on a very curvy trail...the Dream wins hands down and the GJ (and Centurion) are reserved for nice day slow recovery rides. Maybe an occasional 50 miler.

SuperLJ

I was just trying to make the point that the designer who specified the fork on your 70's GJ knew what he was doing. Install a modern fork with a whole lot less rake on your Moto and you will likely increase the geometric trail well beyond what many people would consider a good idea.

In the 1980's (I'm pretty old myself) I had a racing bike that had a front end geometry that produced a trail figure in the 76mm range. It cornered like it was "on rails". Sounds good right? The problem was the rails frequently weren't pointed in the direction I wanted the bike to go. With a very high trail bike it's hard to adjust your line rounding a corner at high speed no matter how good your technique is. A few times I came really close to hitting a car coming towards me in the opposite lane. I didn't understand why that particular bike behaved that way until many years later.

The better designers have had an in depth knowledge for 50 years or more of what range of rake/trail figures work well for a given head angle, wheel size, tire width, handlebar width, weight distribution, and intended use. Replace your fork with one that gives your bike a trail figure far outside the norm, and IMO you're asking for trouble.

Bike handling is based on personal preference though. There's no accounting for taste. My favorite handling bike for a twisty descent would be my '78 Bertin, which I'm guessing has a front geometry and fork pretty similiar to your GJ. No problems adjusting my line at speed through corners with that bike. It has well over 60mm of fork rake and a trail figure in the low 40's.

I would agree with you that "flexy" frames aren't a good idea for loaded touring. That's why better dedicated touring bikes have been made of thick-walled and/or oversized tubing since time out of mind.

Jseis 

Here's an interesting frame builders comments:

https://davesbikeblog.squarespace.com...f-history.html

yeah..after that one descent I realized there was touring and then bike packing and I was doing the latter with the tail wagging the dog. A stiffer, tougher frame would've been the ticket but I was 21 and what the hell did I know? Nowadays I'd probably go XC on a 'cross or similar. I forgot to say that the Dream has shorter chainstays. During the XC tour I watched a gals mixte frame break (upper top tube at headset) and it was obvious that upper top braze couldn't withstand 3000 miles of frame flex due to bike packing.

I admit to being one of those guys who occasionally reads up on frame geometry then thinks "yikes..I could screw that up with my long waisted long arm, long footed, average leg body" or " a stem and seat adjustment could negate any positive intent the designer ever had". Now I'm poking the Frog frame lovers with a thought (just a thought) of swapping out the noodle fork for a steel or CF complement (for once I've reason to go to the Seattle or Portland bike swaps looking for say...a 531 1" fork off a GR.or similar steel 'cross or similar). The trial cost could be less than $100 using an inexpensive threadless bearing set and modest cost steel fork and my curiosity regarding "improvement" is there. What got me going that route was the GJ has a cheap steel fork whose chrome is weak and my converting it to cantis...~36 years ago!

Aside from all that maybe I'll do nothing and just ride the GJ in the STP.

Thank all you for your constructive advice. I promise I won't do anything stupid.

SuperLJ

Thanks for the great link to Dave Moulton's site. I'd agree with everything he said in there.

I was just worried that you'd put a fork on that'd be borderline dangerous. Then I did a little research and found that many aftermarket cf forks have an offset of around 42mm, which, even if your Moto had a head angle of 72, would be 66mm of trail. Well within what is resonable. Your GJ came with relatively wide tires which is why it was designed with a lot of fork rake. As tire widths go down, fork rakes need to lessen to increase gemetric trail, because of the loss of pneumatic trail with skinny tires.

Go ahead and do it if you want. I'm no purist - my all time favorite thread is the vintage bikes with Ergo/STI one.

Time to tie on the feed bag. Happy Thankgiving to you and yours!

Jseis