# Running a fork with less travel than the rear shock?



## mmckechnie (Jul 12, 2010)

I'm looking at picking up a full suspension frame and transferring over my components from my current hard tail. My fork has 100mm of travel, but I think RockShox uses 120mm travel forks with spacers for its 80mm and 100mm travel forks. So I think I can run it at 120mm if I remove a spacer.

Right now I'm looking into a full suspension frame with 130mm of rear wheel travel and one with 150mm of rear wheel travel. Would a 100mm or 120mm fork be too short for either of these frames? There is a lot of information on what happens when you run a longer fork, but not much on what happens when you run a shorter fork. I'm guessing it would help on climbing, but hurt it on descending? It might also make it really handle sharply and act twitchy?

I know there are adjustable travel forks like TALAS for Fox and UTurn for RockShox which allow mid travel bikes to be run at low travel lengths (mainly for climbing?) If I end up doing this I plan on buying a more appropriate fork for the rear shock, but was just wondering if I could get away with it for the time being.


----------



## rangeriderdave (Aug 29, 2008)

It depends on what travel the frame was designed for,it could make the head angle too steep. And if the fork is a sid or something like that it could be too flexy. I would say that a 100 with 150 is too big of difference.


----------



## jackbombay (Nov 15, 2010)

130 rear and 120 front should be ok. The Giant Trance X has come like that from the factory for some time now and it rides great, theres more to it than just the amount of travel of course, but less travel up front is not inherently bad. try to find out how much travel the fork had that came with the bike when new, thats what is more important than more or less than the rear.


----------



## AndrwSwitch (Nov 8, 2007)

It's more a matter of what travel fork the frame was designed for. Matched travel front and rear is most common lately, I think, but for a while, it was frequent for full suspension frames to have more in the rear. Weird, but whatever.

Full suspension frames have the potential to have a more tunable ride, too - you may be able to set it on a lower travel setting, if it has that option, or just run less pressure or less preload in the rear shock. With an air shock, it may give you unacceptable performance...

There are consequences to having too short a fork. Twitchy handling is one. They can also make compressions on trails, like after a water bar, a much more "interesting" experience.

Roadies buy frames and forks as matched sets, much of the time. MTBers tend to tinker too much for such a product to sell well in our market, but you might think in terms of buying them together, if you can't get one designed for the fork you have. (Don't worry about a 10mm difference from spec, btw.) Also, figure out whether or not you can extend the travel on your current fork.


----------



## mimi1885 (Aug 12, 2006)

It depends on what frame are you looking to put shorter front on. Back in the day it was the trend short travel front and longer travel rear. My first 2 FS bike fit the bill, Cannondale Raven 80mm front/125mm rear and Jekyll 80/135. Klein mantra run 80/150, ect. Now the trend reverse longer travel front and shorter rear but not by much.

If you look at the geometry of the bike companies you'd see the disclaimer of how they measure the geo. I often see a 140mm rear travel get spec with 130mm fork. So if it's under 15-20mm swing both shorter or longer you should be ok unless you are a geek about the geometry.


----------



## jpeters (Nov 19, 2010)

I bought a BMC trail fox tf03 frame (see my gallery) and tried the same thing. The frame called for a 110 to 140 mm fork and I had a Fox 32f100 so I put it on just to see. It felt to low and I had to much pressure on my wrists not to mention pedal strikes were more common. 
Since I purchased a suntour epicon TAD with adjustable travel from 100 to 140mm and it still feels to low on 100mm but 110 and up is fine. Its funny you would not think such a small amount makes a difference but it does. the sweet spot for my bike is around 130 bet its ok in all but 100mm.


----------



## jpeters (Nov 19, 2010)

ArielSmart said:


> So howz your bike running now? Perfect?


Me  its good if you are asking me?


----------



## Nadric (Apr 12, 2011)

jpeters said:


> Me  its good if you are asking me?


That's a spam bot. Check the sig.


----------



## mmckechnie (Jul 12, 2010)

I'm coming off of a 2010 Rockhopper with a 100mm Dart 3 SL fork. I'm going to confirm weather or not it can be run at 120mm.

The frames in question are a Jamis Dakar XCT 1. and a Jamis Dakar XAM

http://www.jensonusa.com/store/product/FR264B00-Jamis+Dakar+Xct+10+Frame+Wrs+Bar+Shock.aspx

http://www.jensonusa.com/store/product/FR265B01-Jamis+Dakar+Xam+I+Frame+09.aspx

Looks like the XCT was spec'd to have a HTA of 67.5 with 130mm of travel up front. It has 130mm of travel in the rear. The XAM has a HTA of 68.5 with 160mm of travel up front. It has 150mm of travel in the rear.

Lowering it by 40mm to 120mm would bring it up approximately to 70 or 70.5 degrees, more like my Rockhopper or an XC/Race bike. From the picture it does look like it could be run a little lower than the 160mm fork.

http://www.jamisbikes.com/usa/thebikes/fullsuspension/dakarxam/09_dakarxam1_spec.html

Guessing I'd be perfectly fine running my fork at 120mm in the XCT which was spec'd with a 130mm fork.


----------



## jpeters (Nov 19, 2010)

mmckechnie said:


> I'm coming off of a 2010 Rockhopper with a 100mm Dart 3 SL fork. I'm going to confirm weather or not it can be run at 120mm.
> 
> The frames in question are a Jamis Dakar XCT 1. and a Jamis Dakar XAM
> 
> ...


You should be ok but why don`t you just sell the old frame and fork on ebay and get a rs recon or something like that. Another thing is the steerer long enough?


----------



## mmckechnie (Jul 12, 2010)

jpeters said:


> You should be ok but why don`t you just sell the old frame and fork on ebay and get a rs recon or something like that. Another thing is the steerer long enough?


Okay for which frame? Yeah that's the plan. Sell the old frame and get a used fork from ebay, craigslist, mtbr, or pinkbike. I really want to make the XAM work. Just a little worried on using a 120mm (w/o spacer) fork on a frame designed for the 150mm to 170mm range of forks. Maybe I'll pick up the frame and park it until I can get an appropriate fork.


----------



## jpeters (Nov 19, 2010)

Yeah you cant go 120 on a 150 frame but have a look at suntour they have a real good low cost 150mm fork.

http://www.srsuntour-cycling.com/dstore/products/Forks/2832/DUROLUX.html

http://www.mtb-news.de/forum/showthread.php?t=392001


----------

