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100mm or 120 mm Rockshox fork for a loaded bikepacking bike?

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100mm or 120 mm Rockshox fork for a loaded bikepacking bike?

Old 10-10-14, 05:55 PM
  #1  
bakerjw
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100mm or 120 mm Rockshox fork for a loaded bikepacking bike?

I'm kind of in a quandary and the posters here have been very helpful. Here is the scenario.
I am waiting on a Foundry Broadaxe large frame and am in the process of acquiring all of the components to get it on the road.
The purpose for this bike is only to do some bikepacking. Late next June I plan on touring the upper end of the Tour Divide route.
So, it is not being built to be an aggressive downhill or single track bike. It will be mainly rough forest roads.
Truth be told, if I could get away with a solid carbon fork, I'd go that route. I just like the suspension fork as it provides a margin of error if you hit a rut or something unexpectedly.
Since I'll be bikepacking, I will be carrying a fair amount of gear with weight more to the front than the rear due to the nature of the climbing involved.

I've settled on the Rockshox Reba RL series fork. My LBS spec'd out a 100mm fork as with the lowest price that they could find ($475.00).
I found a 120mm fork for $335.00.

I've ridden road bikes for many years and haven't been into mountain biking enough to be teribly familiar with fork technologies and such. Hence, I am asking here.
I know that the 120 versus the 100 should combined with the head tube angle will have some effect on how a bike handles. Of course I want to have a good handling bike, but I'm thinking that the extra weight on the front of the bike will offset the extra 20mm of fork travel.

With the extra weight on the fork, can you run a little lower pressure to drop them a bit under the load?

Any thoughts or insights are more than greatly appreciated.
Thanks.
John

Last edited by bakerjw; 10-10-14 at 05:56 PM. Reason: details
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Old 10-10-14, 06:33 PM
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I've ridden and raced two different 29ers with Rockshox Reba RL's on them, I'm very fond of that fork. The Broadaxe is designed for a 100mm travel fork, I believe. The current Reba uses Rockshox's Solo Air system, so it's super easy to adjust preload with the single air chamber. The extra weight of bikepacking, within reason and as long as you're not a terribly heavy rider to begin with, should be easy to adjust for. Further tuneability is achieved with the decent damping adjuster on the bottom of the Reba fork. Another nice thing about the Reba: fairly easy to rebuild, replace seals, etc. You'd probably want to have your bike shop do it, but it's a pretty simple fork to work on.

Not that it probably won't work out just fine, but the Broadaxe is a pretty racy mountain bike for bikepacking, not really what the designers of that frame had in mind. Should be a fun bike, though, and again, it will probably work out fine. There are no rules, really, when it comes to that sort of thing.....I take it you will be using frame bags? If you end up getting into more agressive singletrack riding with that bike (just riding, not bikepacking), I predict you'll really enjoy the bike for that, too.

So anyway, my vote definitely goes to the 100mm Rockshox Reba.
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Old 10-10-14, 09:11 PM
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I have a request into Foundry for their recommendation on fork length. And, yes, it is a racy looking frame. When I started looking into frames for this adventure of mine, I came across the Broadaxe at a great price from my LBS and it just seemed to click. I was looking toward an aluminum frame early on and then came across it and something just said "that's the one".

My current MTB is entry level so I'm not up to speed on front suspension forks so I am at the mercy of those who know. I may end up forking out an extra $200.00 for the 100mm, but I'm still early in the build. Thanks for the feedback and suggestions.
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Old 10-10-14, 10:07 PM
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Originally Posted by bakerjw View Post
And, yes, it is a racy looking frame.
Claimed weight is 1010 grams for a 17" frame, and the chainstays are super short for a 29er.....so it's not just racy looking. Have fun with it.
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Old 10-11-14, 04:29 AM
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In the use you are intending the bike for, are you really going to notice 3/4" of travel...Either in the ride or the geometry? IMO both would work as far as travel and terrain, I would however maybe check with the mfg with their thoughts on your estimated loaded bike weight. You will not have a good time if you blow a seal in the middle of your trip...
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Old 10-11-14, 05:36 AM
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Originally Posted by LastKraftWagen View Post
You will not have a good time if you blow a seal in the middle of your trip...
That is something that I'm all too aware of to be sure. Originally I was looking for a run of the mill coil fork with a dampener. Finding a model with a taper and 155mm thu-axle proved to be elusive.
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Old 10-12-14, 02:15 AM
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A 120mm fork could probably have the travel reduced to 100mm by pulling it apart and installing a 20mm spacer.



100mm + 9mm axle + tapered steering = $390: https://www.chainreactioncycles.com/u.../rp-prod109672

Finding a model with a taper and 15mm thu-axle proved to be elusive.
100mm +15mm axle + tapered steering = $350: https://www.merlincycles.com/rockshox...014-65842.html

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Old 10-12-14, 04:15 AM
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Originally Posted by cobba View Post
A 120mm fork could probably have the travel reduced to 100mm by pulling it apart and installing a 20mm spacer.
That is true for the dual-air models, but on the solo-air ones you have to replace the entire spring assembly.
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Old 10-12-14, 08:26 AM
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If you wanted to go cheap with an XC30, you could always find a spring recommended for a heavier rider on eBay.
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