kona fork length help please

[Chris H]

Has anyone got a set of 1997 p2s hanging around that they can meassure bottom race to drop out distance for me. Preferably off a 20 inch framed bike. Trying to work out what type/length suspension forks I can use without upsetting the geometry too much.

Much gratefullness for any help you can give me!!

 

[andrewl]

If you have a 20" frame you actually have quite a few different options regarding fork choice as the longer wheelbase of the larger frame is less effected by different axle to crown heights.

I have a 20" 97 King Kahuna (geo is the same as almost all other 97 Kona hardtails) and am running a 100mm Z1 on the front and it works fine for me, but it probably as long as you'd want to go.

Others have happily run 100mm Fox fork on the 20" frame too.

I tried a 65mm Marzocchi Superfly fork on my frame and found that while it climbed great, it was pretty sketchy in the tight stuff and downhill.

In my opinion I'd say an 80mm Marzocchi is the perfect fork for the bike for all round riding, but your choice will be infulenced by your riding style, the type or riding you do (and where), and what else you are currently riding.

I hope thats of some use.

 

[Anthony]

It's 413mm on a size 17 and I'm sure it doesn't vary between frame sizes.

Andrew and I have had this discussion before, funnily enough. The way I would put it is that the frames were designed for an old-style 63mm fork with c435mm static length, which gave the intended head angle of 70 static, or 71 with rider/sag. The 2003 SIDs that I have on my (97) Kilauea are c455 long (80 travel) and give a head angle of c69 static, or 70 with rider/sag. Andrew is running 97 Z1s with 100mm travel and 475mm length, which must give him 67.5 static, or 69 with rider/sag.

I would have said that was quite a lot of change to the geometry, but Andrew runs quite a lot of sag and anyway he likes the handling like that. I find the Kilauea slightly steadier than I'd prefer, but ok. It's largely a matter of how your personal taste compares to Kona's intended geometry I think.

 

[andrewl]

Dug out my old 97 tech manual and according to that the 71 degree head angle is static with a suspension fork.

Doing a few labourious trig calculations and assuming that the 71 degree head angle is based on a 65mm travel Z2 with an axle to crown of 432.5mm (from the Z2 manual) if you swap to a Z1 with an A-C of 473mm (again from the manual) the net effect is a static head angle of 69.004 degrees for a 20" frame and 68.94 degrees for a 17" frame.

This agrees with the basis of why Kona started quoting sag corrected angles once the 80mm forks were introduced (20% sag is 16mm or almost identical to a static 65mm fork).

Anyway I'm happy to agree with Anthony that 100mm is probably a bit long for the frame but if you are used to riding 5" trail bikes which are normally specced with a 69 degree static head angle then you'll be fine.

Given that 80mm forks are quite common, I'd go for one of those

 

[Chris H]

Thanks guys.

Just built up a '97 hei Hei. Went for 2001 80mm z3 airs as they seemed as they should work but it still feels a bit sluggish and not as flickable as I'd like. Been riding a '90 cindercone fully rigid ss for the last 3 years and I'm a bit dissappointed with the handling of the Hei Hei at the moment. I've got the saddle height the same as the cindercone and seem to get the saddle 'up my arse' all the time when I'm trying to 'go light' over rougher ground - means I can't throw it around as I could with the c'cone. Not sure if the forks have jacked up the front end and moved the saddle back in relation to my normal standing position over the bike. I've also had 1990 to 1995 20' Explosifs, Kilauea and Cindercone in the past without this issue but I've never run any with suspension. Not sure whether to go back to a p2 to get the ride I want. What do you think??

 

[messiah]

Bomber's are long forks which won't help. Moving the saddle forward on the rails to steepen the seat angle back up to the original 73deg might help - it's what we used to to do BITD

My 95 Explosif never felt better than it does now with the original rigid forks - I tied a few sus forks on it over the years but rigid is how it will stay.

 

[Anthony]

Yes, for every inch by which you raise the front end, you will send the saddle backwards relative to bb by about three quarters of an inch.

 

[andrewl]

Thanks guys.

Just built up a '97 hei Hei. Went for 2001 80mm z3 airs as they seemed as they should work but it still feels a bit sluggish and not as flickable as I'd like. Been riding a '90 cindercone fully rigid ss for the last 3 years and I'm a bit dissappointed with the handling of the Hei Hei at the moment. I've got the saddle height the same as the cindercone and seem to get the saddle 'up my arse' all the time when I'm trying to 'go light' over rougher ground - means I can't throw it around as I could with the c'cone. Not sure if the forks have jacked up the front end and moved the saddle back in relation to my normal standing position over the bike. I've also had 1990 to 1995 20' Explosifs, Kilauea and Cindercone in the past without this issue but I've never run any with suspension. Not sure whether to go back to a p2 to get the ride I want. What do you think??

Checking the seta height and angle relative to the rigid setup you like as already been mentioned, but fork setup will also greatly influence how the front end feels.

If your rebound damping is set too slow (or fast) or the oil is on the heavier side which also slows the rebound (and compression to some degree) or the oil height is wrong then it highly likely that the front end won't feel that good - or as good as it should.

As well as checking the saddle height it would probably be worthwhile checking you fork setup and playing around with the rebound.

It should also be noted that a suspension fork will never feel as sharp as a rigid fork, so if you ride rigid bikes predominantly then it will always feel a bit sluggish in comparison.