travel vs. geometry question

[bayarearider]

I am unfamiliar with how the travel can effect the geometry of a bike.  I am finally picking up a razorback tommorow and hope to throw my 100mm fork on their.  I know the frame is spec'd with a 75 mm fork.  Will i face problems by increasing travel up front?

thanks!

my proflex 3000 will be forsale soon (frame only)
and proflex 857 frame forsale right now

[sammydog]

I always thought that increasing the travel would slacken the head angle of the bike.

The effect of this would be to slow down the steering but leave the bike a bit more stable at speed.

When I put 105mm travel marzocchis on my 955 however the bike felt really twitchy and actually steered a lot quicker than it had previously and descended a lot better than it prevously had. I have never really worked out why.

The big downside to the travel increase was that the BB height has been significantly raised which in turn raises the bikes centre of gravity. This may explain why the bike feels twitchy but I'm not completely sure on that one.

[pedro]

the head angle will decrease, the bottom bracket height will increase, however, when you consider the greater sag for the longer travel fork, the difference should not be much.  

After raising the bottom bracket height in one of my bikes, I noticed it is not as agile as before. By agile, I mean I have become clumsier in tight, slow single track, or maybe I need to readjust my handling skills.

The longer travel is worth the tradeoff.

[keen]

  My 01' Disco monkey was spec'd w/ a Noleen Mega air front fork 3.5- 4" travel, 18.5" axle to crown height. I went to a 5" Z1 Marzocchi , 19.75" axle to crown. My head angle went from 70.5* to 67-68*. In my opinion steering suffered badly. I contantly had to fight the bike to turn on single tracks. Climbing was difficult as the front end was always lifting. I settled on a Psylo running in the 4" mode, 19" axle to crown height.

[numbnuts]

If you're planning on xc riding you'd be better off sticking with something close to the original spec's. As far as I've read the Razorback is a sweet ride and one of the most competive fs xc bikes out there. I like the slacker geometry but that is because i like steep downhills, extreme roll offs, rock gardens etc when the extra travel does help. Climbing is harder so it is a trade-off. A very nice option would be an adjustable travel fork, the Black 80-100 would be perfect IMO. I have a Z1 5" on my 2000 Evo and find it to be perfect but I do like to lock it down on the climbs with the ECC.

[Phillip]

The Razorback is a high performance XC model. I think that going with a longer travel fork runs counter to it's basic design and intended use. A 100mm fork will slow down the handling. If I had a Razorback, I wouldn't go over 80mm.

[RoentgenRanger]

It depends on the razorback...if it's a Fox shock model('03, or older model w/upgrade strut), it has a two position shock mount.  It allows you to run a 100mm fork and maintain the same geometry.  Check K2's site, there's info there.  I run 100mm on mine and it's still very quick handling.

[bayarearider]

Wow thanks for the replies guys.  The fork that i have is a Marzocchi Marathon S 2002.  It's such a nice fork i don't want to sell it.  I am guessing the only thing to do is throw it on the frame and try it.

[bayarearider]

hey RoentgenRanger,

i just checked out your gallery.  How much was the fox upgrade for the razorback?

i believe we have the same exact frame.  01 team grassroots model right?

[Carbon_Angus]

one adjustment you may want to try is to shorten your stem a little... maybe 10-15cm. this will increase your steering response.

[bayarearider]

I got the frame today,  But i can't figure out if i need a top swing or a bottom swing derailer.

Also at the lower pivot area (next to the BB) there are these plastic looking washers between the rear swing arm and front triangle.  Anyone know if i am supposed to remove these before riding it?

[Carbon_Angus]

I got the frame today,  But i can't figure out if i need a top swing or a bottom swing derailer.

Also at the lower pivot area (next to the BB) there are these plastic looking washers between the rear swing arm and front triangle.  Anyone know if i am supposed to remove these before riding it?

the first question....bottom pull top swing 31.8
the second..i dunno