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Rigid fork conversion for mid 90s S. Stumpjumper

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Rigid fork conversion for mid 90s S. Stumpjumper

Old 03-31-20, 10:02 PM
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vascoboy
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Rigid fork conversion for mid 90s S. Stumpjumper

My neighbor gave me what looks to be an early to mid 90s Stumpjumper. Im more of a steel/skinny tire enthusiast & clueless about these bikes. Cromoly & cantilever brakes appeal to me, but that spring fork is not my jam. Id like to convert to rigid but want to know what to look for. At 1st glance it looks like to be long (extends about 17 from bottom of headtube). Can someone tell me what to look for? Thanks! Christian
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Old 03-31-20, 11:06 PM
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The general recommendation WRT sus-to-rigid conversion is to look for a fork with an axle-to-crown (ATC) length equal to the sagged length of the fork. The sag is the amount of compression you get when simply on the bike, rolling along on a smooth road. The general recommendation for sag in numbers is about 25%
Its rarely a critical measurement.
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Old 04-01-20, 06:08 AM
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I went through the thought experiment a while back but abandoned the project. The Carver fork is available. 1" or 1 1/8" 410 or 440 ATC.
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Old 04-01-20, 06:43 AM
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What to look for is a fork described as "suspension corrected". Google "suspension corrected fork" and you'll get some results.
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Old 04-01-20, 07:35 AM
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Look for a Kona Project 2 fork. I think they're all suspension correct.
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Old 04-01-20, 07:42 AM
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First thing to find out is, determine year / exact model based on paint color, serial number, original components, etc. Then determine if that bike would have originally had a suspension fork, or if the bike's original geometry was set up for a suspension fork option. It wasn't exactly uncommon for a bike originally specced with/for a rigid fork to be "upgraded" to a cheap (or not) suspension fork, which would have thrown off the overall geometry. So replacing that suspension fork with a generic fork might actually _restore_ the original angles of the bike.
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Old 04-01-20, 07:56 AM
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This might be bad advice but years ago when I bought a cheap bike with naff front suspension I just bought the cheapest rigid forks I could find on ebay slapped them on and was away. It was a 26" bike and a 26" fork. Seemed to be perfect for it, was I just lucky?

In fairness though the original forks were so low end they had hardly any travel at all. I would estimate 40-50mm but the same is also true of some older mountain bikes from good brands.

The bike was transformed with rigid forks, it was lighter with more exact steering it just felt safe and sure footed which it didn't with the stock suspension.
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Old 04-01-20, 08:27 AM
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Originally Posted by madpogue View Post
First thing to find out is, determine year / exact model based on paint color, serial number, original components, etc. Then determine if that bike would have originally had a suspension fork, or if the bike's original geometry was set up for a suspension fork option. It wasn't exactly uncommon for a bike originally specced with/for a rigid fork to be "upgraded" to a cheap (or not) suspension fork, which would have thrown off the overall geometry. So replacing that suspension fork with a generic fork might actually _restore_ the original angles of the bike.
This.
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Old 04-01-20, 08:54 AM
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You can't just buy a "suspension-corrected" fork as most people are suggesting. The Axle-To-Crown (ATC) length of suspension forks changed drastically through the 90s as suspension forks advanced and their travel became longer. A bike from 1993 might have had a fork that had substantially less travel than a bike from 1997, meaning that a rigid fork replacement would need to be a few cm longer on the later model than the earlier.

What I would do is find out what model suspension fork your bike came with. By 1995 it is very likely it came with a suspension fork, but somewhat possible it came with a rigid fork. Once you find out the model, you'll have to look for what the ATC (sagged, like suggested) was for that fork and then find a rigid fork with a similar ATC. A few millimeters off won't matter too much.
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Old 04-01-20, 08:59 AM
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I'll also say before you buy a fork you should evaluate how you're going to use the bike. If you actually do want to ride off-road with it on mountain bike trails (it is a mountain bike, after all), going rigid will hurt you the more difficult the terrain gets. A lot of people seem to want a rigid fork because they don't want to learn how to maintain and adjust a suspension fork, but it does limit what you can do on a mountain bike trail, especially as a beginner.

If you're going to put skinny tires on it - why? You seem to already have road bikes.

One use that a rigid fork is good for is if you want to put wide street tires on as a commuter, gravel bike, or tourer.
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Old 04-01-20, 12:12 PM
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Not intentional but for a few years I somehow accumulated a number of older Stumpjumpers. There was a window of time where full suspension bikes nearly exterminated the demand for hardtails. Garage sales and CL was full of cheap priced and well recognized branding Rockhopper and Stumpjumper's.

Weird looking back, there was a family garage sale where I think to have paid $30 for a neglected Stumpy but while looking around, they had new Wal-Mart full suspension MTBs hanging from the garage ceiling.

I could only take on so many mtb's, fixed and patched up, donated some at Christmas, loaned and sold a few for little profit - actually quite a loss if factoring labor. None were in good condition but when near giveaway, its hard to resist. The Stumpjumper is a great platform to build upon.

Anyways, the search for rigid forks.

I should pull the depicted bike out of storage (and take better pics) but its my one keeper Stumpy- Tange Prestige Direct-drive tubed yada circa 1994?, frankenbuild of whatever parts I had. A real mashup. Though needing a fork, I took a chance at a bike swap meet and paid $10 for this NOS oddball fork.

Its a nice piece- for 26", cast crown, canti studs, Tange ends and brand of Spinner marked on the steerer tube. Perhaps Spinner is the brand.

Delayed the build but when I finally got around to it, I learned why it probably never sold. French threaded. So, I used a mashup of a headset and cups to get it all to work.

Wish I could better I.D. and point one where to buy, but this was a good luck find though a bit of headset issue fitment.




Last edited by crank_addict; 04-01-20 at 12:30 PM.
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Old 04-01-20, 12:52 PM
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Spinner was a huge maker of forks BITD; I see the brand frequently when I pull the fork on a '90s MTB / hybrid for the headset repack.

As for Kona Project 2, I have a Project 2 fork on my Lava Dome, and it is NOT suspension-corrected. I've seen at least one other Kona with a Project 2 that is "standard" length blades. Dunno how widely that applies elsewhere.
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