Mountain Bike Reviews Forum banner
1 - 20 of 28 Posts

·
arbiter
Joined
·
138 Posts
Discussion Starter · #1 ·
Hey all,
I have been turning my 08 RFX into a downhill sled, bit by bit. I am running a vanilla 36 up front, but I find myself wanting a slacker head angle. What would be the best route to do this?

I was thinking of getting a totem or a 66 with a wicked tall axle to crown measurement to do the job, but was curious how it affected the ride and warranty. Also, how about getting a rear shock with a smaller eye to eye to both lower the BB and slacken the HA? Can PUSH do anything about this, similar to the franken-pack-spots?

Drop some science on me.
 

·
Registered
Joined
·
2,029 Posts
That bike will never be a DH bike.... no way no how.

A much taller fork will rase the bb WAY too high (the RFX/pack is already too high to begin with IMO, i ride a 5 pack with a Lyric for the non-DH bike) to have the sort of planted feel a DH bike needs (my DH bike sits at 13.8" bb).

You could put a 7.5 X 2 shock on the back to drop the rear and slack the bike a bit (really the only way to make the bike more slack without absolutely killing the geo/ride) but you would obviously loose travel (not a terrible thing).

If you really want a bike that will do 'DH' type riding and still allow some pedaling, look at a Highline if they are not all gone already....
 

·
arbiter
Joined
·
138 Posts
Discussion Starter · #3 ·
The Highlines are all gone (from Turner at least) and I cannot afford two bikes of that caliber, so I need the RFX to be able to handle nastier DH stuff here (windrock, snowshoe, etc,) while being able to pedal the trails as well.

For what it is -a trail bike- the RFX is damn near perfect. I would just like +1 degree for the heinous high speed rocks.

Do you know anyone that has the smaller shock setup? Didn't FM do this?

-Thanks!
 

·
Registered
Joined
·
2,029 Posts
futuristxen said:
The Highlines are all gone (from Turner at least) and I cannot afford two bikes of that caliber, so I need the RFX to be able to handle nastier DH stuff here (windrock, snowshoe, etc,) while being able to pedal the trails as well.

For what it is -a trail bike- the RFX is damn near perfect. I would just like +1 degree for the heinous high speed rocks.

Do you know anyone that has the smaller shock setup? Didn't FM do this?

-Thanks!
Understand 100%. IMO it makes a great 'heavy duty do all' bike, just wanteds to make sure you were not spending a ton of $$ to try to make it something it will never be.. I put the 5 spot rear on my pack for exactly the same reason....slacker and lower!!!

I am sure someone has at least tried a 7 X 2 shock on a new RFX, but mine (prior version) already takes that size stock, so a shorter shock was not an option for me. I think the shorter shock would reduce travel by about 3/4 inch, drop the bb about 1/2 inch and slack the angles by almost a degree......sounds pretty good to me.
 

·
Registered
Joined
·
9,469 Posts
futuristxen said:
Drop some science on me.
7.75x2.25" Avy is the ticket, it will get you a good bit closer to the Highline. :thumbsup:
Since getting the avy on my RFX, I definitely choose that bike for many rides where I used to want the highline. I pretty much only chose the highline for Lift/Shuttle rides now... This bike saw some great use last year, including garbonzo trails and some westside at whistler, some northshore, and a downieville trip, as well as lots of great local stuff.

More info here and here

 

Attachments

·
arbiter
Joined
·
138 Posts
Discussion Starter · #6 ·
Did the bb height take some getting used to? What was the HA? How'd she climb on techy sections? Was the drop in travel noticeable with a superior shock?

On another note, anyone interested in a DHX coil and RP23 shock for $450?
 

·
Banned
Joined
·
16,457 Posts
futuristxen said:
The Highlines are all gone (from Turner at least) and I cannot afford two bikes of that caliber, so I need the RFX to be able to handle nastier DH stuff here (windrock, snowshoe, etc,) while being able to pedal the trails as well.

For what it is -a trail bike- the RFX is damn near perfect. I would just like +1 degree for the heinous high speed rocks.

Do you know anyone that has the smaller shock setup? Didn't FM do this?

-Thanks!
IMO, there's nothing wrong with you wanting to do this. In fact, there's a thread running on the Banshee forum on the exact same topic, except with a Rune. One has to understand the frame will have limitations, but you obviously know that, and you also know what your target is and that's where the fun is, so that is no problem. There's no shame in wanting to use one heavy duty bike for such applications, and expanding its scope of use.

As far as the A2C height, if you can handle a King, use the +7mm crown race from Ventana. This will get you a bit more on top of a longer fork, plus help keep the controls out of the way of the downtube if there's a risk of interference. Both of our 06 RFX's have the races, though we ride more heavy duty trail stuff. I wanted a bit better descending in the rocks and mostly got it, though I still sometimes imagine myself on an 07 66 RC2x instead of the 36 TALAS.
 

·
carpe mañana
Joined
·
7,297 Posts
The rear end from an 04-07 5 Spot will drop the BB a tad as well, the asymmetric stays have slightly taller seat stays than the older variety. That will help drop your BB a tad. A shock like a CCDB, which runs with greater sag % than typical, will have you riding lower in the rear, deeper in the travel, making the front end slacker. Also, put a slightly smaller tire in the rear than the front for a little extra drop in the rear.

_MK
 

·
Registered
Joined
·
9,469 Posts
futuristxen said:
Did the bb height take some getting used to? What was the HA? How'd she climb on techy sections? Was the drop in travel noticeable with a superior shock?
a 7.75x2.25" Avy will lower and slacken your bike, without reducing travel, and it improves suspension performance. It's a shorter i2i length with the same stroke.

There are some other good ideas in this thread, but many of them trade something potentially "good" to get slacker angles. A taller fork or crown race will raise your BB (potentially good for chunky gnar, but not so much for railing berms). Putting a shorter shock on obviously will reduce travel (probably good for smooth steep trails but not so much for rocky gnar). So I guess it all depends on your trails and use….. but the avy doesn't require you to sacrifice anything (except steep angles).

The quality of the suspension is incredible improvement for me (I was running a roco TST previously FWIW). I noticed the biggest improvements on high-speed stuff and square edge hits. The shock also pedals very well.

The geometry changes look subtle on paper but the difference is definitely noticeable- the BB drops about 3/8". I'd guess this takes about 1/2 degree off the angles. I could feel the difference right away but it wasn't so dramatic I needed to adjust my riding style. The changes were all for the better on tech/FR/DH and technical climbing was fine, but the bike does feel less efficient on fire-road climbs. This is how I get to my favorite trails, so I eventually went up #50 on the spring and backed off the preload- this gave me the same %30 static sag, but less squat on steep seated climbs.

Hard to say since it depends so much on ones' trails and riding style…. For me the RFX with avy & burly wheels is usually enough bike. I've been stoked to have the highline for shuttle/lift days, but owning it is a luxury for me.
 

·
Registered
Joined
·
927 Posts
I remember reading somewhere here that DT tried a 7.75"x2.25" shock (like FM's) together with a zero stack height headset, which resulted in a lower BB plus identical angles to the original geometry. Sounds interesting.
 

·
Registered
Joined
·
9,469 Posts
tald said:
I remember reading somewhere here that DT tried a 7.75"x2.25" shock (like FM's) together with a zero stack height headset, which resulted in a lower BB plus identical angles to the original geometry. Sounds interesting.
I don't think he was referring to a 0-stack headset (not aware of any being made for 1-1/8"?)- I think he was talking about having an adjustable fork.

It's a great point though, thanks for bringing it up. :thumbsup:

I'm running a Talas 36, it's cool with the lowered Avy since I can dial the front down for situations where I want to steepen up the head angle. For instance in downieville this year, I spent a lot of time with the fork at 130mm- then you're getting a 13.75" BB and roughly 69d head angle. I use the Talas feature a lot on rolly trails and climbs.

Lowering the back end without an adjustable fork will definitely impact climbing.
 

·
Registered
Joined
·
927 Posts
Ah - found it
"...My personal 0708 RFX has a BB that is lowered by a PUSH shock that is 3mm's shorter and I dropped the fork travel 10mm with Fox spacers, shazam, that bike geometry is now right on 14.1" with 2.5" nevegals now" (DT)
 

·
trail fairy
Joined
·
9,546 Posts
I wanted the same thing back in 06 when I already had a 5spot in the stable, I probably should have got a HL but I didn't want an 8inch bike if the GEO was what it turned out to be in 07 I woulda gone for it, I could have had an 07 RFX but went with the 06 instead!

On the 06 imo it does not raise the BB too high, it didn't for me, for single track or going downhill the BB never came into the equation regarding handling, maybe it was my setup, wheelbase or overall numbers, 06s were longer in the TT than 07s, 08s another reason I wanted to choose it, I ran a 06 66 RC2X on mine and this was actually quite common back then, when the Homers were hardcore, 66SLs mainly though I think most adjusted there travel for lower ride height, I never found this so much an issue more the overall weight would catch up on long rides over 2hrs or with long climbs not what the setup was for. I wanted no adjustments and full coil.

Handling wise its still been one of the best rigs Ive pointed downhill, I know I'm gonna miss that fork and wish I'd hung onto to it, especially with the later models issues.

This rig was totally connected to the trail, railed corners especially if you ride more a DH style than XC, it was a great setup, yet could handle narly rooty wheel swallowing ruts and mud at my favored ride spot a place where even on the uphill light rigs with steep geo had no advantage at all, only once on the fire road were they happy. One reason I love that place not so much about the bike, more about the rider it is mini Dh heaven!

If wanting a more all round ride I would suffer on longer more XC rides its could be done and well, I could ride hills even with my short stem [50mm] but not fast, just roll on up, but that was not the intention, 5spot was for those rides, also ta front and rear so I could still ride hard!

If you the big fork route, unfortunately for the RFX those forks are now 180mm or fortunately for the HL this is good, not sure how this will affect the bike, EL C did it on a large, but a large RFX & longer the wheelbase will probably bring it in line so not so bad, but you will sacrifice something, maybe not on the downs or corners, and if ya riding this way, I don't see how you will be affected, you are already riding aggressive and adjust if ya BB is higher than normal, you might run a little more sag as long as its balanced you'll pop through corners,

BB is not the be all and end all end of day riding skill is what you need to develop, too many dis this,I like to have it low too but sometimes its about setup rig and dialing in the ride look at the top DH team of the year, highest BB bike in DH V10 BB now lower to 14.8" nearly 15"

14" 14.5" is not a deal breaker, can't handle that then give up riding imo!
Mine was 14.5 I think from mem with 66 170mm and 2.5" tires, funny with a swap of my shock to DHXa for some testing it dropped below 14" I did post some measurements here last year, same eye to eye, so something weird from Fox and the difference between Cane creek you can see the change in rocker angle in my picc's I have the DHXa on there at mo as have no coil and not sure what I want to do there until I'm riding again! I did measure the shocks but don't remember the numbers, stokes were the same but i2i was diff :confused:

FMs route is probably the best way to go though since ya riding an 08 hes got it pretty dialed, my above comments are really so you're not afraid to try it our especially if you've got another bike in the stable!

07 I did a 6hr Super D on this bike below, with 66rx2x 2 Ply DH tires cause the course was full of rocks little over kill, I could have used my DT 5.1s and saved some weight, I ran my DH Sun MTX's! it never held me back I rode with one brake the rear Hope was leaking and lost pretty much all use, Fred Flintstone copy through the corners, this course was mainly downhill and corner after corner!

RFX with 66 06 model @ 170mm very capable downhill, wheels were directly of the Spot at the time, 2.5BG Kenda, rear 2.4 NN schwalbe, bit light for the RFX, norml Dh tires were my Minions!

Wet tire setup DH wheels



current, poo air shock only for holding bike together a coil will be on there for riding when I'm back in the saddle, not sure Avy or Roco tst and push it, Roco appeals cause parts are easy to source here and service etc, though I'm sure not too hard to deal with Avy cost maybe a factor eek, the Van front as this will be my more all round ride when back so hence the less FR/DH nature of it but still hopefully a mini DH ripper, dropped allot of weight with the fork so will ride all day well now, don't think it will lose to much on the downs! Looking fwd to trying it out..would till like to try some 5.5 rockers I think!


Choose ya fork wisely its a big investment and go enjoy playing around I say or choose a top coil fork @ 160mm maybe even the 09 Marz 55RC3 FMs geo and rock it 07/08s have a few more options since the ratio change and 121 you could alter this to lower BB as others have said or pick up a HL if ya can still get one! :thumbsup:
 

·
~~~~~~~~
Joined
·
5,931 Posts
one thing I've wondered about but never researched is swapping the air sleeve of a rp3. Can't one just take a shorter can and screw it on? I assumed PUSH cut and machined the existing one for their mod? Looks like the 7.5 is 3mm shorter than a 7.875...
 

·
Registered
Joined
·
557 Posts
I emailed Push regarding shortening an RP23 and a DHX-c a few weeks ago. Their response was that the stroke had to be shortened to reduce the i2i on the RP23, and never answered regarding the coil.
 

·
carpe mañana
Joined
·
7,297 Posts
Or you could put a 24in wheel on the back. Instant geo adjustment on the cheap.

_MK
 
1 - 20 of 28 Posts
Top