# Rigid Fork Length for replacing 100mm Shock



## Stevob (Feb 27, 2009)

Is it 425mm or 445mm? I'd think 445, but just want confirmation from someone who's done it already. I can't find my tape measure to measure my fork. Help.

edit, sorry. For 26" wheel.


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## The Diesel (Apr 4, 2008)

Im also interested to know. Soon my old trek 4300 will become a single speed rigid urban/trail bike and it currently has a 10o mm on it also.


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## boomn (Jul 6, 2007)

Sorry, I don't know 26" fork lengths. If you do measure don't forget to take sag into account.

Anyway, I can offer this: you don't necessarily need to match the same height. You won't be flying downhill at the same top speed so its ok if your bike is a little twitchier at high speed with a shorter fork. Also, you will have to pick and weave your way through rock gardens and such so being able to turn a bit quicker can be a benefit. I switch between a 100mm suspension fork and an rigid fork that's the height of a sagged 80mm susp fork and also has a lot more rake (which makes it steer even faster). The quicker feel of that shorter fork goes great with the precise steering feeling of riding rigid

EDIT: I did find this document from RockShox that summarizes axle to crown lengths for their forks. Subtract 20% of the travel to find an equivalent rigid fork length


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## The Diesel (Apr 4, 2008)

boomn said:


> Sorry, I don't know 26" fork lengths. If you do measure don't forget to take sag into account.
> 
> Anyway, I can offer this: you don't necessarily need to match the same height. You won't be flying downhill at the same top speed so its ok if your bike is a little twitchier at high speed with a shorter fork. Also, you will have to pick and weave your way through rock gardens and such so being able to turn a bit quicker can be a benefit. I switch between a 100mm suspension fork and an rigid fork that's the height of a sagged 80mm susp fork and also has a lot more rake (which makes it steer even faster). The quicker feel of that shorter fork goes great with the precise steering feeling of riding rigid
> 
> EDIT: I did find this document from RockShox that summarizes axle to crown lengths for their forks. Subtract 20% of the travel to find an equivalent rigid fork length


interesting, i cant wait to get a rigid on it. My only concern is the wide trek frams looking funny with a skinny little surly rigid or something.


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## Stevob (Feb 27, 2009)

I've ridden rigid before, but that was on a bike not designed for a suspension fork, a 1997 Giant Yukon.

FWIW, the research I've done since has shown that 445mm is the popular choice to replace 100mm forks. I just wish I could find my tape measure.


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## Stevob (Feb 27, 2009)

Thanks for the document boomn, I found my fork on there and it's 471mm, so take a bit of sag off and 445 sounds right, but put a bit more compression into the picture, like in corners, it comes down further. So I suppose it's a bit suck it and see. I'd hate to loose grip on corners, so I might go for a 425mm and just live with the twitchyness.


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## Stevob (Feb 27, 2009)

20% of the travel is only 20mm, so by that reasoning, 445 would be closest.


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## 45ronin (Apr 1, 2006)

*Fireline 26er rigid option*

Anyone running a rigid (carbon or ti) fork on a 26er Titus Fireline? If so, opinions and specific length/offset are welcome.


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## roybatty666 (Mar 2, 2009)

I run a 445mm White Bro Carbon fork on my Scandal which is set up for a 100m fork, which is the correct length when taking into account sag.


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## luapmichna (Mar 13, 2010)

How would a 445 mm fork work on a bike set up for a 80mm suspension fork?


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## PutAwayWet (Jul 6, 2004)

FWIW I have a 438 mm Vicious which I've run on a Gunnar Rockhound (designed around 80 mm fork) and a RM Blizzard (80 or 100 mm) and that A-C length seems pretty good. It was actually racier on the Rockhound, less so on the Blizzard, if you can figure out where your frame geometry fits in relation to them...


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## digitalkoh (Sep 11, 2009)

*would 445mm work on 29er designed for 100mm*

I am replacing my Reba 100mm with a rigid. 
I ordered an Exotic carbon 465mm, but they sent a wrong fork with 445mm.

I am debating whether to return this and get the 465mm or just use 445mm.


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