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Fork Upgrade

1K views 9 replies 8 participants last post by  NFLcheesehead1 
#1 ·
I'm trying to upgrade my fork on my 2012 Trek 4300 26''. Currently, I have a Suntour XCM v3, but it is definitely not suitable for the trails I've been riding on. I'm thinking about doing the SR loyalty program and getting the Raidon LO R Air for $150 bucks. On the other hand, I just found a fox racing fork with a 50% discount from Pricepoint.com. Here's the link. I'm pretty sure the fox fork would fit on my bike, but could someone help me verify that? I feel like I should jump on the fox fork 32 float 140 RL Open Bath 2011 for this price ($299)...what do you all think?
Here's a pic of the fox fork
 
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#3 ·
Your bike was definitely designed around having 100mm of travel. Putting 40mm more travel on it would not only make the bike handle and feel different, but it could also damage your frame and void any warranty you have on it. Stick to 100mm of travel if you buy a new fork.
 
#9 ·
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I had my 2012 29" Fox 32 Float RL 100 apart.

There are rubber bumpers at the bottom of the slider tubes. It looks like adding bumpers would limit travel, but you would still have 140mm of extension which seems wouldn't be buying you anything.

I think the extension is limited by the damper. So MAYBE you could just replace the damper with a 100mm one.
Finger Product Line Thumb Electric blue
 
#5 ·
I was afraid 140mm would be overkill...the Raidon LO R Air is 120mm, and I was told that would be fine for my frame. How exactly would 140mm damage the frame?
 
#7 ·
How exactly would 140mm damage the frame?
Your head tube sees a lot of forces. If you were 200+ lbs and hit the brakes hard, that would make the fork pull back towards the center of the bike, as your weight is still trying to move forward, putting a lot of strain on the head tube, compressing the down tube and putting tension on the top tube. Hop a short set of 3 steps and land on some hard surface like concrete and your weight would try to continue move down, but your bike absorbs it, and the fork would try to bend forward and upward a little, putting a lot of strain on the head tube, compressing the top tube and putting tension on the downtube. Even rolling over roots and hitting rocks and hitting "G-outs" will put a strain on your bike similar to heavy braking. Not all of the force is absorbed by the suspension fork, due to it not angled perfectly in line with the force vectors.

The longer the fork (more travel), measured from the axle to the crown, the more leverage there is from these forces, which multiply them. Longer fork = ever more strain on the frame. Frames, especially Treks, are designed to be lightweight, with designers making it for a specific type of riding, making it as fun to ride as possible (sluggish and tanky is not that fun). They would need to put more mass in appropriate areas on the frame to handle such forces from a longer fork. Thicker tubes for strength and durability, larger box sections for stiffness, and plates (gussets) welded on top and under the downtube to reinforce the bike to brace against such forces. Making the bike stiffer and stronger is not always the best answer. A stiff bike might just buck you if you try such maneuvers and didn't use your body's strength to counter/absorb the forces, leading to crashes, while a not so stiff bike might act well behaved and absorb some of the forces for you, and make it so you can ride without worrying about little stuff like that. A stiff bike would be super responsive, which some pro riders like, but under a beginner... well, some people like to learn the hard/painful way.

You asked. That's more of the dumbed down version of my explanation, trying to make it easy to understand. Dunno if you would understood if I basically said "leverage" and "frame weight optimization".
 
#6 ·
The longer-travel fork would exert more torque at the head tube.

To be honest, I'd be more concerned about it messing up the handling. IME, 20 mm changes are noticeable already. Too far and you could have a bike that handles really weird.
 
#8 ·
For 150 the Raidon would make a major change to the capability of your bike and give you a chance for good skill development. You should have a lot more fun and be able to handle a broad range of difficult trails.
The Raidon has a sealed damper like a shock on a car. It doesn't need the oil changed so maintenance needs are very low. The Fox is the opposite.
You can outgrow it and when you do a completely different bike setup is likely, not a 4300 with a 140.
 
#10 ·
I think I'm just gonna go with the Raidon...I figure I'll just save some money, plus it sounds like the 140mm fox fork would cause more trouble than it's worth. But it sure does look sick...oh well
 
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