Convert to Rigid Forks. I'm Confused!

[Zenroad]

I am now about to build up an MTB for the first time ever. I've owned several, but have never messed around with the forks.

I have an On-One 456 EVO steel frame. I want to put rigid forks on. I'm totally confused about the numbers. Suspension corrected? What should I be shopping for in rigid forks? What numbers do I need to look for for this frame? I don't care whether the forks have rake or if they are straight, as long as they work for this frame.

Can anyone give me a quick tutorial? I'm so confused. It's mm this, and mm that. I've fallen and I can't get up! Maybe I should just buy a horse.

 

[Cyclist33]

Not sure where your confusion lies as you haven't entirely been specific! But essentially, you want the geometry of the same bike to be as close to being identical whether you've suspension or rigid forks. Or conventionally that's the wisdom, anyway.

So really all you need to do is measure the length of a suspension fork from the dropouts (where it clips onto the wheel axle) to the soffit of the crown (ie the mid-point of the underside of the "bridge" piece that links the two exposed parts of the fork legs and slots into the front head-tube; and then make sure that any rigid fork has the same measurement. I would imagine also measuring the internal width from one fork leg to the other would be useful to ensure wide tyre clearance.

Try to get one with a long steerer, that's the metal shaft that slots upside the head-tube. I think from memory, something over 250mm in steerer length is wise. Key principle is, if the steerer's a bit long, it can always be sawn down, but if it's too short, you can't use it.

Looking at the specs of the frame on the website, it says it has a conventional headset. All things are relative so what was conventional once isn't now, but it looks like it uses a fork of 1.125 inch (often expressed as 1 1/8") steerer diameter. Almost all relevant available forks can be bought in that size. Make sure you don't get one with a tapered steerer coz if the headset isn't a tapered type then the fork won't fit.

That's about all I know on the subject.

Stu

 

[ColinJ]

Wouldn't you have to allow for the normal compression of the fork with the rider's weight on the bike?

 

[Zenroad]

Thanks, y'all. I'm really ignorant about this stuff. All that mm stuff and suspension correction business. I know the 1 1/8" thing--standard now, used to be 1". And I know the 100mm OLD for front dropouts, but that's it for me.

I'm looking at the Orange F8 forks. Does anyone know if these would work on the 456 EVO?

 

[Cyclist33]

Wouldn't you have to allow for the normal compression of the fork with the rider's weight on the bike?

Easy if building for self and not a fluctuation weight wise. Harder if building to sell?

 

[Cyclist33]

But solid point.

 

[lukesdad]

The 456 is designed for long travel forks. The F8 is designed to replace short travel forks less than 120mm

 

[Bodhbh]

Hello, I keep posting on your 456 threads....

I've got Orange F8s on a 456 I use for touring, but it's an old one not the EVO. I am not sure on the difference on the geometry (if there is one). It handles okay, but I'm fairly ignorant on geometry subtleties. You will need to bodge a bracket to mount the fenders is the minor issue. No rack mounts, but guessing you might be using something like the Old Man Mountain racks anyhow.

I'll see if I can find a photo somewhere, as you are building something not a million miles from what I have.

I'm probably going to turn the 456 back into a MTB and put all the bits on a 29er frame of somestripe for touring. I might be asking questions myself on that soon

 

[Bodhbh]

Not sure if it warrents a seperate thread, but was reading about people sticking rigid suspension corrected 26er forks on a 456 and sticking a 29er wheel in there and the geometry panning out about right. I'm tempted to have a play with that as have a spare 29er wheel kicking about.