Yes, this is another 69er project.....I do have a MC 29er and like it alot. But has it's limitations for my trialsy style on some techy trails.

I have an Evil Sovereign (long size-24.15 tt) that I ride singlespeed with an older Z1 fork (518mm a-c, 130mm travel). I've been wanting to have a rigid option for some trails and was thinking of using a 29" front wheel.

What fork length to make decent handling with good steering?
According to Evil w/ 26" wheels:
4" fork ~ 70 degrees HA
5" fork ~ 69 degrees HA

Taking note that most 29er hardtails have around 71-72 degrees HA, I'm thinking that the fork length almost needs to be as short as possible and still fit a 29" front wheel....like the 1x1 fork. Am I wrong in interpreting the lack of slack HA's as meaning they don't work well with a 29" wheel?

Three candidates w/ different a-c's and an estimate of resulting HA with a 29" wheel:
1x1 413mm 70ish degrees
Salsa Cromoto 425mm <70 degrees
Surly Instigator 447mm <69 degrees

I have a wheel and even an extra crown race, so what fork should I try?

There's discussion of an instigator on a Chameleon here:
http://forums.mtbr.com/showthread.php?t=276995&highlight=instigator+fork
And the report is good handling w/ a 29" wheel, but the numbers make me leery....seems like it would be a bit floppy?

A 72º HTA 29"er is not to be compared to a 69º 5" 26"er.
Especially when the front ends is only different by wheel size and fork length.

Take into account that 20mm shorter a fork equals ~half an inch more seat-bar reach.
In trying to get twitchy handling, you'll get a racey-long feeling top tube. Totally different bike that happen to use the same set of frame tubes.

the latest issue of dirt rag (issue 127 pg73) has an article on figuring the change-over for the 96/69er...for what its worth. but sounds like you will want to have a 29er front wheel to start. it seemed pretty strait forward: (i'll paraphrase)

STEP1
take a pencil, string and tape measure-tie one end of the string to the middle of the pencil-put the pencil in the dropouts like an axle and pull the string taught-mark where the a-c height is. take your measurement from the string. this is the a-c measurement (L)

STEP2
measure the radius of your 26" wheel and tire in millimeters(R1)

STEP3
measure the radius of your 29" wheel and tire in millimeters(R2)

STEP4
use this equation to determine what rigid fork will keep your frame geometry close to the original setup: R2 - R1 = Rd

then use your answer in this equation: L - Rd = desired fork length

not rocket science but hope that helps in your quest.

A 72º HTA 29"er is not to be compared to a 69º 5" 26"er.
Especially when the front ends is only different by wheel size and fork length.

Take into account that 20mm shorter a fork equals ~half an inch more seat-bar reach.
In trying to get twitchy handling, you'll get a racey-long feeling top tube. Totally different bike that happen to use the same set of frame tubes.

Thanks Cloxxki....well, my goal is certainly not quick steering, but rather I just want to avoid being too slack.

Maybe my concern is unfounded and I should just go with the 447mm a-c surly fork....that plus the ~33mm difference in wheels (thanks khenry) gives an (effective) a-c of ~480mm. This is close to the sagged a-c of the Z1 that I've been riding.

Cloxxki, what fork would you recommend?...i'm sure you understand the implications of different forks much better than i.

Hey, I'm doing the exact same conversion. Going with the Salsa Cromoto at 425mm to have a slightly sharper feel, since it's going to be a trailbike and not a freeride-y kind of thing.

Hey, I'm doing the exact same conversion. Going with the Salsa Cromoto at 425mm to have a slightly sharper feel, since it's going to be a trailbike and not a freeride-y kind of thing.

Please let me know how it goes....haven't done anything yet.
Good luck!

Check out the link below for some Evil 29er coverage.

http://forums.mtbr.com/showthread.php?t=78424

http://i206.photobucket.com/albums/bb130/pruittt/sov69/P6300030.jpg

It turned out pretty good. Been riding it for a couple of months. Trading off between a Large 29er Monocog. I'll probably choose it over the RL for most rides. It's quite a bit more fun on low speed technical trails (most of my rides). Very agile with the short chainstay and wheelbase. And the high BB is definitely a plus in rocky areas.

Have tinkered with the bar quite a bit and have settled to where it's at--works well for singlespeeding at this height (34.5" inseam).

Numbers as currently setup w/ Instigator fork.
bb: 13.125"
wb: 41.5"
cs: 16.0"
wt: 28#
ha: ~69-70
trail: ~90mm

The steering is no problem. Seems fine. I think a taller fork with more offset might be a little better for me to get he font end higher without the extreme riser stem.

My bikle has a Ha 71, its set for 120mm forks could i put on a fork specific to a 29; frame with my current 26'' wheel and get a good rise on it? I dont want to nosedive on the way down decentshttp://forumprog.free.fr/GS_e4ff864dac21276d2991bfb466f37adf.png

Ripley: Nice looking bike. I am considering the fit of a Sovereign. I want to be able to get enough seat post extension to make it versatile for me. (I am 6'6") Might I ask how tall you are? Inseam? How long a seat post you are running? And if you've got much extension left?

Thanks, josh

Ripley: Nice looking bike. I am considering the fit of a Sovereign. I want to be able to get enough seat post extension to make it versatile for me. (I am 6'6") Might I ask how tall you are? Inseam? How long a seat post you are running? And if you've got much extension left?

Thanks, josh

Josh, I'm 6'0" with a true 34.5" inseam.
Running a Thomson 410mm 31.6 post.
I believe there's still a couple of inches of post left before being maxed out.
I'll measure when I get home this pm and edit and add the info to this post.

I know That Syncros and a few other companies make a 425mm seatpost as well.

Thanks for the info Ripley. I appreciate you checking into it for me.

Thanks for the info Ripley. I appreciate you checking into it for me.

At full extension of the Thomson 410mm from center of bottom bracket:
1. measured 28.5" to saddle rails
2. measured 30.75" to top of saddle (WTB Laser V)

Pic at full extension.....

that looks like a fun bike./

cool bike, good job

Do you get any noticeable wheel flop on the bike? I really do dig it.

It certainly looks fun! :)

Do aquatic creatures from Pluto nest upon your bottom bracket threads just out of interest.

Do you get any noticeable wheel flop on the bike? I really do dig it.

I may have noticed some floppyness at first, but now it seems normal to me. I like low-speed very technical trails and it seems to work well for that. But it's quite stable at higher speeds. I'm really having fun with the bike set up this way...suits my style. In fact, i'm about to unload the Monocog 29er, cuz I just have no interest in riding it. Which means my front wheel will also be gone :( Guess I'll use a 26" wheel until I can pick up another 29". 12" bbh is too low for my style/trails.

I just put a One-On carbon fork on...picked it up used with the intention of using it in building up a light-weight 29er. Been wanting to raise to front end up a bit, so thought I'd try it on the Evil, and maybe pick up the steel version if I like it. Have only ridden it once....felt OK, but the bars were too high. It did feel a bit floppy in a couple of places on the trail.

Here's a pic with a different stem and a little lower bar height. Plan to ride it this evening.

For anyone interested, here's some measurements with the two different rigid forks:
ac offset bbh wb
Surly Instigator 447mm 43mm 13.125" 41.5"
On-One Carbon 470mm 47mm 13.375" 42.0"

Chainstays @ 16" length (adjustable 15.5-16.75")

-rip

you could get your bars lower with a different stem without any problems.

Lookin good!

you could get your bars lower with a different stem without any problems.

Lookin good!

No kidding... huge stem angle there in my eyes. Lots of room.

But people run those stems for their own reasons, so that may not be doable.

:thumbsup:

you could get your bars lower with a different stem without any problems.

Lookin good!

That pic is already after putting on a different stem. The bar height is about right in the picture.

No kidding... huge stem angle there in my eyes. Lots of room.

But people run those stems for their own reasons, so that may not be doable.

:thumbsup:

looks steep, but the stem in the last pic is a 100 x 10 degree.
guess the slacker HA gives it a steeper look.