I'm looking for a new bicycle to replace my stolen gravel bike, and one of the options I have is a 12,6kg full CrMo steel framed gravel / trekking bike that seems cheap and robust enough. My only concern is that my previous bike was 9-10 kilos, with an aluminium body and carbon fork, and it rode really well, so i'm a bit worried it might not be as fun on longer rides.

So that got me thinking: how much weight could I reduce by switching from a steel fork to a carbon fork, and how easy is it to do it myself? Would it be worth it?

My vote is skip it. The potential weight savings is not worth the cost and messing around with.

A carbon fork can save around a kilo, which is both a lot and not that much depending on perspective. Personally I prefer the ride characteristics of a carbon fork over a steel fork, so that’s also something to consider. I find steel forks to either be too noodley, or too harsh, or kinda both. Carbon forks more often feel stiff without feeling harsh.

A fork swap isn’t hard to do, but I would be surprised if the cost of that bike plus a carbon fork isn’t more than just buying a bike that already has a carbon fork. Also finding a compatible fork may or may not be difficult. For example if it’s a straight 1-1/8” steerer with disc brakes your options are pretty limited. Also need to keep the forks axle-to-crown height and rake in mind.

The bike I'm looking at would be 1100€ new, 450€ used, apparently in "good" condition

And it would be another €400+ for a carbon fork from a reputable brand, unless you can find a used one that will work. I would not trust cheap aliexpress forks.

What bike are you looking at specifically? In that price range I’d rather get hydraulic brakes and at least an 11 speed groupset than a carbon fork. Unless that bike is just a killer deal and already has that stuff

https://activebikes.com/product/2022-active-sirocco-gravel-360-silver/

I'm just looking for a do-it-all bike, one that I can take on a train, ride in cities, roads and on gravel roads. 50% commuting, 50% leisure. My old bike was 2x10, I thought it was good enough but a bit hard going uphills

Edit:

I feel like 450€ for this would be pretty good, I could afford to put on some nice tyres and invest in a proper saddle and somehow bags as well.

Ride it and see. Depends on your personal frame too 😀.

Like I have fluctuated between 94kg and 83kg, depending on my powerlifting or couch sitting routine, so 3 kg on the bike frame becomes irrelevant

Yeah €450 isn’t bad. For a casual bike it will be fine, but I don’t think it would be worth changing the fork.

I don’t know what the Finnish used market is like, but I would be surprised if you can’t find at least a 2x10 gravel bike for a similar price. But if 9 speed is fine for you, yeah it looks like a good quality bike.

I feel like the punishment/weight ratio is rather logarythmical, as in it increases with route steepness but not in a linear way - you'll start noticing it on really steep gradients and with tiredness.

If you have a somewhat decent shape and don't ride over too much steep gradients I'll say just keep the steel fork. It's cheaper if you just lose a kilo yourself than in your bike. And depending on the builder, steel frames and forks can feel as flexy if not even more than carbon.

I don't think it is really about weight but more about ride quality. I think it is worth it. STEEL RENEGADE
Side note SRAM 1 by systems are pretty cool. Snappy

9 speed chains are hella cheaper too

just for fun HY/RD

I'll have to see how the brakes are before committing, but yea enough people have recommended hydraulics so I think eventually i'll have to get them haha

Cable pull hydro best of both worlds. Never owned them but got to try them out though.

Juin tech is also a great option for hybrid brakes.
If you go down this route you must install compressionless brake hoses (eg from jagwire)