Weight difference between steel and carbon forks
 

Hi!

I've a bike with a steel fork (2016 Trek FX 7.1), and to lower weight I'm thinking of replacing the steel fork with a carbon one (the carbon fork of the Trek FX 7.4, with is 100% compatible).

The problem is that I can't find online the weight of my steel fork, and neither the weight of the carbon fork of the Trek FX 7.4

I have asked trek customer service, but they have not been able to tell me that info.

So the question is:
Let's suppose that the steel fork was of excellent quality, and of low weight to be made of steel, and that the carbon one was not so good and of high weight to be made of carbon (to put us at worst!), do you think that there would still be a noticeable weight difference, that would make the replacement worthwhile?

What do you think? Would be a "low quality" carbon fork, still be way lighter than a "high quality" steel fork?

https://cimg5.ibsrv.net/gimg/bikefor...8bb6102453.png

https://brainybiker.com/carbon-vs-st...-and-analysis/

Thanks Rolla !

OK, so (on average) it will reduce weight in about 500g... 🤔

That trek fork may be exceptionally heavy for a carbon fork. Do they list a weight?

No unterhausen , they don't list the weight of the carbon fork (neither the steel fork to compare)...

I asked to the Trek customer service, but they say they don't have that info... 🤷🏼‍♂️

Pretty sure the forks on my Worskwells were under 400 grams uncut .... 390 grams I think. Are these heavy-duty or disc forks?

For whatever you are trying to achieve, I think its a complete waste of time and totally redundant, when you can easily make more of a difference than 500g with your own fitness and performance levels.

Those are not mutually exclusive choices, as has been pointed out to the many before you who have repeatedly dredged up the staggeringly obvious "Lose weight from your body instead! It's free!" argument.

The bike in question: https://archive.trekbikes.com/us/en/...7_1_fx/details ?
https://cimg1.ibsrv.net/gimg/bikefor...cb4cfbac8f.png
You could save a pound by swapping the fork and you would still have a 26-28-pound bike with w low-level drive train and heavy wheels, designed for casual, comfortable low-speed riding around town..

You could save another pound by spending another $300-$400 and upgrading the drive train a few levels.

After all that money, I honestly doubt you would feel any difference in the bike's performance.

As @Rolla said, you could do a lot more to change the bike's responsiveness by investing $400-$500 in lighter wheels and tires.

After all that, you would end up with a bike almost as good as a new bike which would cost the same.

I would not put a penny into that Trek. I would ride it it and enjoy it as is, while saving up for a better bike more suited to the type of riding I actually do. If you actually do casual, low-speed riding around town, the bike is already perfect.

If it was a mountain bike and the front shocks were in need of replacing I could see swapping to a steel fork on the cheap which is what I did on my 29'er.

Otherwise, save your duckets for a better bike if this one does not meet your specs.

This is the best advice you've gotten so far. Take heed.

Your initial question is totally different from your hypothetical question.

To answer your hypothetical, a lower quality carbon fork for that bike would probably weigh 850g. A high quality steel fork for that bike would probably weigh 1100g.

A high quality steel road fork can weigh 750g, but your bike isn't designed for that style fork.


Now for reality-
Your fork is heavy. I have worked on countless fx1 bikes(over 100 of em) in all 4 sizes and the forks are at least 1250g.

Thanks Maelochs !

Yes, I think you're right, but the truth is that since I already had the bike, and the size and frame geometry are PERFECT for me, I thought it would be better for me to change certain things to my liking than buy a new bike.
Anyway, I've already "update" parts of my bike, so now buying a new one is not an option

In fact, actually I've changed a lot of thing of my bike:

Now, I've in my bike:

Lghter wheels; Mavic Ksyrium S
Lighter tires: Pirelli's 700x28c
Lighter Front transmission: Shimano GRX 40T (1x)
Rear transmissión: Shimano Ultegra (11v)

So, for me, is a lot better bike now.

But, would love to keep "slimming" it, and I think the fork is where you can reduce more weight with less money... especially if we consider that the original fork is made of steel, not aluminum!

The problem is that I can't find info anywhere about the weight of the FX 7.4 carbon fork.

If mstateglfr is right (thanks mstateglfr too for that info!), then my steel fork must weight (at least) 1250 grams, but I can't find info about the weight of the FX 7.4 carbon fork... 😭

According to the table of Rolla , IF the steel fork of my FX 7.1 weight is 1250g, and supposing that carbon fork of the FX 7.4 weight a bit more than the heaviest of that list, lets say 650g, I would be saving (in the worst scenario), 650g, and will cost me around 200$

Anyway, what I don't understand is why Trek dosn't have the weight of their bike parts in his database for when a client call to his customers service (they have the measures, but not the weight)! 😡

Yeah, I think it's pretty safe to assume you'll cut the weight of the steel fork about in half.

I bet you're the first person to ask how much that fork weighs. It wouldn't be hard to take it off and weigh it yourself, btw. :)

Yes, I'm almost sure that probably I've been one of the few that maybe have asked them the weight of a steel fork, cause usually who buy a bike like this doesn't care too much about weight (I didn't when I bought it!).

BUT, would be very easy for them to have that data (same way than Shimano does, for instance).

Now, I used more my bike for "aerobic training" and sport, not for commuting, and I'm beginning to care about weight, I've swap some components, etc...

Light bikes nice.

OP, you seem pretty invested in this project, regardless of the merits. I expect you'll have to order the fork through a Trek dealer. Maybe it's something that could be returned to Trek if the weight savings doesn't suit you. Or if it's only $200, just do it....

Lighter components and shaving off few grams of weight isn't going to improve your aerobic fitness. You're wasting your money.

Take off your fork and weigh it.

If you are buying a new CF fork, there is no reason to limit yourself to the Trek FX one. If you are going to bother doing this, get a nicer one that you know the weight of.

Just be aware that some carbon forks my actually result in less tire clearance than your steel fork. I see you're running 28's. Just be sure the new fork you buy has enough clearance for larger tires.

I did this with an old peugeot and a Nashbar 1" threaded fork, I found 28's would not work with my fork. Granted, I was using 25s and had no issues. But did test with a different wheel/tire and found a conti GP 4000 SII would not fit.

Also consider it not soo much the weight diff but rather the feel and vibration diff.
Many love steel since its real and has more classic feel.
Others love carbon for the stiffness.
There is a reason why many of the steel / AL bike started using carbon forks and seat tubes.
Some frames even mixed carbon and steel, ie rear triangle carbon tubes.

I replaced a Gunnar steel fork with an NOS Reynolds Ouzo Pro full carbon. The Ouzo is a high-quality fork that was at the cutting edge of lightness in its day, the Gunnar is made by Waterford, and is also excellent quality, although I don’t imagine that weight savings were a primary concern. With both steerers cut to length, the weight difference was exactly one pound (450g). No real difference on the bike in terms of weight (except in my head), although the CF reduced road buzz somewhat. I did the swap because the bike was originally spec’d with an Ouzo Pro, but I “garage doored” the original and replaced it with the Gunnar. I was perfectly happy until I came across the NOS uncut Ouzo for a killer price (~$130) and I couldn’t resist. The Gunnar is wrapped up in my spares box

What nobody has asked yet is how much you're willing to spend on this fork swap? Are you looking at a full carbon fork, or one with an aluminum steerer tube? Do you have the tools to cut the steerer tube and insert the needed star nut (or expander nut)? So, all-in, what do you expect to spend to save this 1 pound?

carbon is lighter than steel

If this is what you want to do, do it. There are a lot of ways to live, and no matter which ways you choose, a lot of people will say you are wrong. I wouldn't have started on the project, but apparently you are well into it and enjoying it---so why stop now? Get a lightweight fork with the tire clearance you need .....

One thing .... look at your brake options. Right now it looks like you have cantilever brakes, which are not common any more. You might have a hard time finding another fork, particularly in CF, with cantilever posts. The Trek fork probably will (I assume) but you might be better off going with modern dual-pivot front brakes.