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Old 10-24-11, 10:22 AM   #1
digger
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Adding less front travel on new frame

I recently purchased a Kona Tanuki frame, not the full bike, just the frame and rear shock (I got a good deal on this frame).

I want to transfer the fork from my hardtail to the new Kona frame.

The fork in question is a 2010 Marzocchi Corsa Ti RC with 100mm of travel.

The Kona Tanuki, as a complete bike, comes with a fork of 130mm of travel.

I have been told by a LBS employee that putting a fork with 30mm less of travel on this bike would "seriously affect the handling of the bike from what Kona had designed."

I asked in the Kona forums and a Kona Techie stated, "The fork could cause some issues. It is an inch shorter than stock so it will steepen the head and seat angle by a degree and lower the BB by nearly an inch."

But the techie did not say anything about "seriously affecting the handling." From what I can gleen from the techie response is that the handlebar won't be as high and there will be less clearance underneath the BB.

Used for heavier XC riding on ATV trails with rocks. No jumps, freeriding, or drops (I'm too old).

So, if I put this 100mm travel fork on this bike are we talking about such bad handling that it will be unridable? Would I even notice a difference? Or even a big difference, between a 130mm and 100mm fork (excluding amount of travel or "bounce" available, of course)?
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Old 10-24-11, 04:26 PM   #2
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The bike came with a zero clearance headset, so if you can run a standard headset you can make up about three eights of that inch. for xc if you run a 2.0 on back and a 2,4 on front you make up another eigth of an inch?
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Old 10-24-11, 05:47 PM   #3
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Originally Posted by born2bahick View Post
The bike came with a zero clearance headset, so if you can run a standard headset you can make up about three eights of that inch. for xc if you run a 2.0 on back and a 2,4 on front you make up another eigth of an inch?
Hi Born2,

Thank you for that advice. Just so I understand, you're speaking of using a standard headset to raise the handlebar height right?

That seems to be a wise idea, me thinks.

BUT, since this bike has a tapered head tube; 1 1/8" to 1.5" and I am using a standard 1 1/8" fork, then I need a reducer in the bottom of the headtube. From what I understand, there are not that many companies supplying this type of headset, with a reducer. The one I have ordered is a Cane Creek zero stack headset. See image.


Regardless, I am already using about 30mm of spacers now.

I do not understand what you mean by; "run a 2.0 on back and a 2,4 on front...[to]make up another eigth of an inch." Would you be able to explain that please? Do you mean tire size?

My original question was probably not clear though. I am wondering what are the ramificatons of putting a 100mm fork on a bike that comes stock with a 130mm fork?

Suppose, in the future, I wanted more travel up front, does that mean I cannot use a fork with 150mm of travel then? That it would "seriously affect the handling of the bike from what Kona had designed"?

In short, I have a fork (6 months old) that I want to use and I do not want to have to purchase another one. But, if the "handling" or "usability" of this bike is going to be so bad, then I will.....but I'd rather not.
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Old 10-24-11, 06:24 PM   #4
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I'm not talking about raising the bars as such, I'm dealing with the distance from the axle to the crown on the fork. The inch Kona was referring to is there. The bigger tire on front would make up some of this as i said. Look up Axle to crown measurement and I think you will see what I'm saying. I'm currently running an 80mm travel fork on a frame designed for a 100. But the difference in the axle to crown measurements of the two forks was only a half inch. Take a measurement of the fork you have and compare it with the online mesurement of the fork that the bike was specced with and you should know exact numbers.
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Old 10-25-11, 03:41 AM   #5
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Also, I'm not familiar with that particular bike, but if it was built with a more slack geometry, and you plan to just ride it on xc type trails, dropping the front and giving it a bit steeper of a head-tube angle might not really be a problem anyway. Do you know how many degrees the head tube angle is with the bike in stock form?

I'm guessing headtube angle is the handling issue the bike shop guy was talking about. Once you get past a certain point, the bike will become twitchy and more difficult to keep going straight down the trail.
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Old 10-25-11, 07:26 AM   #6
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Quote:
Originally Posted by born2bahick View Post
I'm not talking about raising the bars as such, I'm dealing with the distance from the axle to the crown on the fork. The inch Kona was referring to is there. The bigger tire on front would make up some of this as i said. Look up Axle to crown measurement and I think you will see what I'm saying. I'm currently running an 80mm travel fork on a frame designed for a 100. But the difference in the axle to crown measurements of the two forks was only a half inch. Take a measurement of the fork you have and compare it with the online mesurement of the fork that the bike was specced with and you should know exact numbers.
I've emailed Marzocchi to ask about the distance from axle to crown. It does not seem to be shown on their website. HOWEVER, the fork length (not sure if that is the same distance) on the one I have is 472mm. I cannot find anything on the stock RockShox Tora 302 Solo Air. GAH!

However, comparable forks on the RockShox (Sram) website, although do not give this distance, most of them are adjustable anyway. Some can be adjusted from 80/100/120mm. Others from 120/130/150mm.

So, if a forks travel can be adjusted, thus changing the axle to crown distance (??), then why is it an "issue" for me to use a 100mm travel fork?


Quote:
Originally Posted by 3speed View Post
Also, I'm not familiar with that particular bike, but if it was built with a more slack geometry, and you plan to just ride it on xc type trails, dropping the front and giving it a bit steeper of a head-tube angle might not really be a problem anyway. Do you know how many degrees the head tube angle is with the bike in stock form?
.
No, I don't know, but the Marzocchi techie said that the Corsa fork, with 100mm of travel would slacken the headtube angle by 1 degree.
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Old 10-25-11, 03:14 PM   #7
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Ok the Corsa A/C measurement is 467. The Tora is listed at 505. That makes 38 mm or a litlle over an inch and a half which would be closer to 2 degrees change in headtube angle. Now XC probaly won't be the end of the world but I would still try to go with a normal tapered HS and a reducer if you can find one. bigger tire on the front wont change the A/C but will still raise the headtube and slack the angle a bit.
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