Road bike carbon fork: tapered or not
 

Grateful if somebody can explain me:

What are the advantages of tapered 1 ⅛ – 1 ¼ inch carbon fork over non tapered 1 ⅛ for road bike? I saw that tapered is usually more expensive.
Can I use (adapt) 1 ⅛ fork instead of 1 ⅛ – 1 ¼ tapered? How can I do this and what would be the disadvantages (if any)?

Thanks

The theoretical advantage is the tapered fork is a bit more rigid. The real advantage for a road bike is about zero.

What is your current fork and headset? If the fork is 1-1/8 - 1/1/4 and so is your headset, using a 1-1/8" straight steerer fork will require a new 1-1/8" lower headset cup and crown race. Cane Creek sells individual lower cups/bearings and crown races. You will have to match the frame's headtube ID and headset type.

Thanks.
Actual fork is 1 ⅛ – 1 ¼. Is it possible just to use some sort of adaptor to increase from a new 1 ⅛ to the old 1 ¼ diameter and use the original headset, incl. bearings?
Headset cup is integrated.

What type of headset do you now have; press-in cups, zero stack, integrated? What is your frame's headtube ID? What you need to convert it will depend on the type.

The cups are integrated - part of the carbon frame: 1 ⅛ inch at top, 1 ¼ at bottom above the fork blades. I can't change those, as they are parts of the carbon frame. The headset if FSA, with 2 different diameter bearings, to fit the integrated cups.

There might be some sort of adapter race that could be put between the bearing and the fork, but probably not. And the replacement fork would probably need to not have a bevel for the bearing but be the square type that can accept a race.

I hope you're asking because you have limited cash and a free fork. If not, get something 1 1/4. There is no good reason to change this, and the 1 1/8" fork crown might look stupid with the 1 1/4" head tube.

Thanks. I am asking because tapered looks to me too expensive for (probably) no benefit. For example, I can find Columbus 1 1/8 for around 250 EUR. But for tapered 1 ⅛ – 1 ¼ I can only find Enve at 470 EUR. Almost double.
Simple 1 ¼ (straight) would not work, because the upper cup is 1 ⅛, integrated as well.

Tapered Columbus for 270 Euros
https://www.chainreactioncycles.com/.../rp-prod181893

Wait, you say you need 1-1/4" at the bottom? Hmmm...

Are you going to use QR or Thru axle front wheel? Rim or disc brake?

If QR rim brake, I'm not familiar with this brand, so not sure I'd go this route, but
https://www.ebay.com/itm/294189577855

Thanks.
Yes, rim brake and QR. I don't know that brand and I am not very happy to buy from Ebay (you don't know what you really receive, and a fork is a very important component). But I shall look in more detail to that.

The advantages of 1 1/4" at the bottom of the head tube are that (i) the strength of the fork/crown junction is increased (higher resistance to shearing forces) and (less crucially) (ii) vertical forces through the bearing surfaces are distributed over a greater area and among more bearings. The upper bearings usually undergo much lower stress and last much longer, so it makes sense to stick with the smaller-diameter 1 1/8" standard there.

Why are you replacing the fork, by the way?

Thanks.

I want to upgrade a secondhand bike that I used a few years on the smart trainer. I think that a minimum safety measure before using it on the road would be replacing the old fork. So, I try to keep investment at minimum. It looks that a straight 1 1/8 would be sufficient for the scope, but now I start to have doubts that it is technically possible.

My observation is that forks seem to be well engineered to not fail. The usual failure, if any, is either the top of the steerer from stem overtightening or the occasional bond failure on a metal dropout (which doesn't usually cause a crash). So I wouldn't replace it if there isn't something obviously damaged.

Also, consider contacting the maker for a "crash replacement" price on the same fork.

Agree in principle. But being an old secondhand bike, I do not know what kind of abuse it took. Crash replacement would not work, since it is a secondhand bike with no purchase documents and unknown history... No problem for using years on trainer, but not safe on the road.

I think Kontact is referring to a crash replacement policy, offered by some manufacturers, whereby they will sell a discounted frame or fork to someone who owns a frame or fork of that brand, regardless of whether it's the original owner. It's basically a marketing thing, intended to throw a bone to people who wanted a frame or fork replaced free, under warranty, in instances where the damage was clearly from a crash and not from a failure due to material or workmanship.

Is there a reason you trust the frame?

I have a Fuji tapered fork laying around. Carbon fork with aluminum steerer. PM me f you are interested. Thank you.