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Discussion Starter · #1 ·
Folks...hoping some of the experienced 69er's can point me towards a rigid fork with either disk or v-brake mounts for use on my '99 S-Works M4. I'll mostly be using the bike here in the midwest as my utility/cargo/truck bike - towing my BOB with tools for trail work, occasional grocery getter, that sort of thing. I've got a rigid 29er as SS or 6 speed as my dedicated single track bike.

Hoping someone familiar with the S-Works M4 geometry might be able to point me in the right direction. The only option I've really contemplated at this point is a Karate Monkey fork but I haven't researched its compatibility with this frame.

Thanks for your help!
 

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you could use the KM fork for sure, although it could potentially be a bit tall.

i'd say find a salsa or surly 26" fork (with a disc tab) which both fit a 29" tire with a lower A-C height than the KM fork, and run a mech fr disc....
 

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This is so odd... I was riding the Trek dedicated 69er that just came out for most of the weekend... (will post up review, etc, later tonight). I liked it enough and I have all the parts lying around to convert my '98 M2 S-Works to a 69 and will be doing it tonight. I also had an '01 Stumpjumper M4 frame but the rear chainstays were only 16.25". I am a tall guy to I ride with the seatpost all the way out. In the XL size, I was having a lot, so I was worried about liftup in the front. I had a lot of trouble keeping the front end down of the '01 M4 geometry, I had to move the seat almost an inch forward of neutral on the post.

I have been riding this '99 M4 (a great, classy, super rugged and stil light frame) as a single speed for a while and noticed and it felt like the rear wheel was a little farther back but always thought it was the same as the '01 geometry with those short rear stays and it was in my head. Not so, I broke out the tape measure and did some google searching to confirm and it is about 16.9" rear chainstays. I did the math, and this geometry with a 29er fork is nearly identical to the new Trek 69er. It will be '72 degrees seatpost (73 stock) and the stumpy is 71 stock HA, and the Trek 69er is 69 degrees head angle. I bet it will be about 69.5 or so with the 29er White Brothers Fluid on there. It's only weakness is room for narrow tires only and no disk bosses so it will be v-brake in the rear and on a Jones 2.1 (which is fine for me/this bike).

You have to check to see if your M4 geometry has the 16.25" stays. If so it would probably still be fine but you might need to make some compensations to keep the front down.

I was going to post up a thread about this, will do it or add to this thread later tonight when I get it dialed...
 

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I mounted up the White Brothers fork to the M2 last night. The Fluid 110 has too much axle/crown at 510mm, it is definitely rideable but it raked the front out quite a bit at probably 69 degrees or maybe even less. When I inverted the stem it made a big positive difference. It is an interesting bike now, it feels really agressive and could probably take any descent very meanly now. Went from being very XC to quite AM -- I am actually pretty excited to go ride it. It is tall enough up front that with gears I would be concerned about lifting up the front. With a single speed you are not geared low enough where it is that much of an issue. Regardless I moved the seat father forward and mounted that stem inverted and rotated the handlebars farther forward so I am moved forward on the bike. It still put the tire noticably under my ass, I had to air up the rear a little because I think I had too little air pressure with the increased emphasis of weight on the rear... I will post up a pic later. At first it looked a little goofy but I put about 3 miles on it last night mostly on the street and it did great. It also rumbles literally over anything. The White Brothers fork also turned out really light, 3.8lbs. Very excited...

I now don't think the Trek geometry is right on their site, there is no way it is a 69 front rake, it still seemed much more like 71 degrees or higher, I was just believing what I read on the site.

The Reba would be a better option at 472mm (80mm travel) and 492mm travel for the 100mm travel...
 

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Do you want to run a rigid fork or a suspension fork up front?

If rigid - look into the Surly 1x1 fork, or the Salsa Cromoto fork, or perhaps even look into one of the many rigid carbon forks available these days - do a search on ebay for rigid forks and you'll see what I mean.


If suspension fork - look for an older White Bros as those have probably the lowest AC heights of the 29er forks out there these days. An old CX1 would be an ideal fork for such a set up - but they are hard to find these days.
 

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Ideal would be a suspension fork... It is the oddest thing, iI have a Karate monkey fork somewhere that is completely MIA... I don't think I recall ever selling it? Otherwise the fork I took off was a 1x1 but I stupidly did not get the one with the disk tabs. So I am limited to 26er only rim brakes, but the Nevegal / 29er just barely fits.

Anyway, ran home for lunch and took a pic. It is going to look funky-looking but actually rides pretty well and I think it would be decent on the trails. Notice how I moved the seat forward on the post to place it better over the pedals. Remember this is an XL frame so bigger than it looks... Last pic shows how it has been setup, as an XC single speed...

Also for this length/frame (16.9) I found 36/21 works with no tensioner for trail riding, and 36/15 as a townie/just slow enough to get up hills like what you would see in San Francisco and such...
 

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oh crap...
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551 Posts
Discussion Starter · #9 ·
I think I'll start off with the Surly 1x1 fork if you guys are sure it will run a 29er wheel. What tire size am I limited to?

At first I'll just mount up my current front wheel and V-Brakes, and will later on switch to a 29er wheel and disc brake. I just want to get it converted soon because the current suspension fork is nearly shot and I want to get the front end firmed up.

Looks like I can get one for about 60 bucks on eBay.

Thanks!
 
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