Fitting rigid forks to front suspension frames ...

[Chrissy_J]

... good idea? bad idea? really dangerous? nothing to worry about? I don't know.

I have a couple of frames salvaged from the recycling bin, one steel and unmarked, one alloy (a DiamondBack MT20). Both of them had cheap sus' forks that were rusted solid and so got binned.

I just want to put a bike together so I can go places with my kids that my ex-racer singlespeed won't take me, but because these frames were presumably designed with different geometry for suspension forks I don't know whether fitting a regular and inexpensive set of rigid forks is safe to do so. I don't have the cash to buy and try, in case it goes horribly wrong, so I just wondered if anyone had any words of wisdom on the subject...

 

[Osella]

Not much wisdom needed - have a look around & get a set of rigid forks of the right length..
You need to ensure that the steerers are the right diametre (1" or 1&1/8" most likely) and ensure that you have the right steerer type (threaded/unthreaded) depending on the headset - so some more details / pics of the frames would help if you have any? Also details of the original sus forks will help to ensure that the rigid forks are the correct length to match the handling as it was designed. Depending on the frame, there may be considerations of the type of brakes used - again, pics/details will help.

Many people change from cheap front-sus to better rigid forks, some do it to save weight, or many other reasons, so you're in good company!

 

[mattr]

I'm running rigid on a couple of front suss frames, just a matter of getting the right axle to Crown length.
IIRC 440mm is about right for a sagged 100mm suspension fork. So ok for most xc ish frames.

 

[dirttorpedo]

As noted above its not a big deal. The key is acquiring the right fork (steering tube diameter) and length. I believe there are three sizes (at least that's what I've encountered). First size is for old school bikes designed before suspension came around. The next is the fork for 80mm suspension corrected frames. These are typically early/mid 90's frames to late 90's. Then the last one is for 100mm suspension corrected frames. These are for frames built from late 90's to present. There is some flexibility though - I'm running an 80mm suspension corrected frame on my 2000 Rocky Mountain Hammer which according to my research was able to handle a range of suspension forks (80mm, 100mm, 120mm). Putting a smaller fork onto a frame than it was designed for will lower the headtube and steepen the steering tube angle which will make the bike steer faster. Surly makes both 80mm and 100mm suspension corrected steel forks in 1 1/8th size. You can get them for v-brake/canti or disc.

I'm running the 80mm 1x1 fork on my Hammer quite happily at the moment.

 

[Chrissy_J]

Okay. I had a look in the spare room where all this stuff lives and it turns out that the steel frame came from an Argos BSO, so I'm discounting resurrecting that for the moment. That had a 1" threaded headset.

The alloy DB frame was stripped of components and had its headset removed some months ago but I'm pretty sure it was threadless... the bearing shell measures 44mm in diameter and the head tube measures 150mm in length. Course, I forgot to take any pics and those I can find online aren't much use as they're too small...

 

[dyna-ti]

Personally i do not like the sound of this in the slightest :shock:
Effectively youll be constantly changing the head angle and im sure it will reach a point on full compression where the angle is too steep and something like the crown/leg will go :?

But go for it though remember to bring a mate with a camcorder. Worst happens and its £250 of youve been framed

 

[mattr]

Erm, he's talking about turning a hard tail into a rigid. No changing of head angles there......

 

[Osella]

Okay. I had a look in the spare room where all this stuff lives and it turns out that the steel frame came from an Argos BSO, so I'm discounting resurrecting that for the moment. That had a 1" threaded headset.

The alloy DB frame was stripped of components and had its headset removed some months ago but I'm pretty sure it was threadless... the bearing shell measures 44mm in diameter and the head tube measures 150mm in length. Course, I forgot to take any pics and those I can find online aren't much use as they're too small...

Cool, threadless suggests 1& 1/8" which makes it easier to find forks. 150mm headtube is tough tho, as with added height of a headset you'll need a long steerer, which can narrow the 2nd hand choices. Have a look for P2s, Salsa Cromoto, or On One and Exotic if the frame's worth a Carbon fork.. Just make sure they have the right brake mounts!

 

[dyna-ti]

Erm, he's talking about turning a hard tail into a rigid. No changing of head angles there......

:facepalm:

Im thinking full sus.


Right. Tum tee tum

Rigid fork on rigid frame- no problem there just the length to work out seeing theyre unlikely to be sus adjusted frames so a 395mm would be fine with a 420mm(80mm sus fork equivalent)
As most are of the era that they were thinking more on fitting sus forks i think youll still find that it was calculated that a 65mm wouldnt compromise a non or as yet non adjusted frame. Not sure about 80mm. Might find thats ok also but a shorter steerer would help the twitchy steering. :?

 

[jimi911]

I have two 26ers I have done this to. Both suspension adjusted, though early 90s so that adjustment is not drastic.

I have a Trigon Carbon fork (about $200 shipped) on my Ti Wheeler and a Mosso aluminum fork (about $60 shipped) on a Norco frame. Both work fine and are easy to work with. I ride my Ti bike as my trail bike and the Trigon has held up very very well. For just messing around, go with the Mosso. Great value and a quality item. Downside to the mosso is that it only comes in white and black and the graphics sorta stink. I stripped mine to be powder coated the same as the frame so it looks pretty. The Mosso has disc mounts if you need them to.

http://www.mosso.com.tw/fork.php