Big Bike Thread

weescott · 3 Apr 2011 at 17:41

Without a shadow of a doubt. I found the 203mm V2 too much at the rear. You only need 203mm rear or venti discs if you are doing mega long Alps runs IMO.

6thElement · 3 Apr 2011 at 17:51

You only really need the V2's on a bike used purely for DH imo, I've got them on my big bike and I wouldn't put them on one of my XC bikes.

KnightStalker said:
On a related note, my lbs has some mavic EX823 rims with the spoke cups and are willing to let me have them for 50 each, but probably overkill for my HT.

They're for DH wheels, overkill and too heavy for your bike.

janesssssy said:
So, can you ride that out mountain biking, or just on the road. Only asking as you have TT bars on.
How long did 81 mile take you?

40 miles of that 80 was on dirt/singletrack

Can't remember how long without checking, but I wasn't in a hurry. Just got back from a 60 mile road ride, just eaten lunch and then back out again for the same.

ichabod crane · 3 Apr 2011 at 17:56

6thElement said:
You only really need the V2's on a bike used purely for DH imo,

What if you are fatty and you need the stopping power

KnightStalker · 3 Apr 2011 at 18:03

6thElement said:
They're for DH wheels, overkill and too heavy for your bike.

Cheers 6th, i thought as much ill get them a miss then, why are wheel choices soo damned massive with huge price differences, its really starting to annoy the hell out of me. Ive already got a nice little front hub ready to go, 9mm thru axle jobby, so im looking at a rear hub plus rims, or totally forgetting that get a nice cheap 32hole wheelset and rebuild my hub onto the front.
Im getting more aggressive on my bike too, taking more jumps and drops as i gain confidence so ideally need something that will take that sort of punishment.

booyaka · 3 Apr 2011 at 18:10

Anyone got some decent pointers to "roughly" setting up forks?? I appreciate that it's all about personal settings/testing etc

According to the info on the forks about weight/PSI etc - i should have about 120/130 PSI in the positive and negative chambers but with that I can hardly move the forks at all.

I did find this information but not sure as following his guide - i only need about 65/70 psi to get 90% travel on the forks when really forcing them down.

hm .. why do i have a 150 mm fork, if i am limiting its travel by setting the sag to exactly 30%? maybe someone needs 20-25%, maybe another one needs 40%. why is this so?

i adjust both, fork and shock, this way:

(fork) negativ chamber empty, comp and rebound full opened and positiv chamber 25% sag at the beginning. my fork has 150 mm of travel. ok. i need 90% (135 mm) of the travel for trailriding and the last 10% for bigger hits. so i roll slow on a descending road (how steep, is irrelevant) and try to compress (no bunnyhop!) the fork very hard with all my bodyweight (standing on the bike in downhill position = not over the handlebar, but centered over the bottom bracket, well, just like i ride the bike on a downhill). then i take a ruler and measure if the rubber ring has done it to about 90% (135 mm). if so - perfect!

if it's under 90%, i decrease the pressure about 5 psi and try it again until i reach the 90% of travel.
if it's over 90%, i increase the pressure about 5 psi and try it again until i reach the 90% of travel.

how much psi in the negative chamber? it depends on, if you like your fork softer or firmer. softer: lean your bike against a wall. pump up the negative chamber, until the fork begins to compress by itself to a maximum of 1 mm. firmer: decrease the negative pressure about 5 psi stepwise, until you think it's good for you.

rebound: at the beginning better slower than faster. and i don't middle out things 50/50. i rather devide in three thirds. so every time at the beginning, i set the rebound between 2/3 and 3/3. you have 10 klicks? set it to 3-4 from turtle. you have 15 klicks? set it to 5 klicks from turtle. 20 klicks? 6-7 from turtle ...

now i leave the descending street or the parking lot and try out the fork on the trail. at first the fast sections. the rubber ring is less then 90% up on the fast trail, i decrease pressure by 5 psi, until i have a usage of 90%.

then i move to the hardest sections and try to find out, if the remaining 10% have enough progression for not bottoming out the fork. if (not) ... then ... (and do not forget to adjust the negative chamber to the new positive setting at the end!)

if you ride your bike hard it could really be, that you will have less sag as you have assumed (and vice versa).

I understand the whole rebound side of things but seems to be a large difference between real world to get even 75% of the full travel of the forks and next to nothing when pumped up to the aforementioned 120/130psi.

Been googling for a while but getting more confused!

KnightStalker · 3 Apr 2011 at 18:13

Booyaka ive got the same issue with my '10 Rev Dual Airs, ive never got the PSI thing down either, if i run lower pressures to get the Sag, the first hard hit they bottom out, so pump them up by 20 psi and i lose all small bump response, making them rock solid on the small and rough stuff. So im also very interested in knowing how and what, im about 150lb geared up 11stone.

booyaka · 3 Apr 2011 at 18:21

KnightStalker said:
Booyaka ive got the same issue with my '10 Rev Dual Airs, ive never got the PSI thing down either, if i run lower pressures to get the Sag, the first hard hit they bottom out, so pump them up by 20 psi and i lose all small bump response, making them rock solid on the small and rough stuff. So im also very interested in knowing how and what, im about 150lb geared up 11stone.

glad i'm not the only one!!

I'm a bit "bigger" - about 15 stone. 130psi is recommended for me but even with full open compression i get almost zero sag and even jumping/pumping the bike up and down get barely 30% movement.

weescott · 3 Apr 2011 at 18:23

Rode the Hammer and The pink fluffy bunny today (rode the mast blast once last year).

Lots of wet baby heads for my 2.0" tyres to slide off.

I'll have to go back up on the Tracer soon. Lots of jumps and drop offs. Really good trails. :cool:

KnightStalker · 3 Apr 2011 at 18:29

booyaka said:
glad i'm not the only one!!

I'm a bit "bigger" - about 15 stone. 130psi is recommended for me but even with full open compression i get almost zero sag and even jumping/pumping the bike up and down get barely 30% movement.

Thats exactly how mine behave, And the massive kicker, people say Set the sag with only + in, well you do this and i get the correct sag at 30 Psi, which is just bloody stupid and by far not the correct way of setting these Rev's up, plus with just + they have no - to create any spring type of reaction.
changing in 5 psi amounts does nothing either, as you probably lose that 5psi when you disconnect the pump lol.

booyaka · 3 Apr 2011 at 18:51

KnightStalker said:
Thats exactly how mine behave, And the massive kicker, people say Set the sag with only + in, well you do this and i get the correct sag at 30 Psi, which is just bloody stupid and by far not the correct way of setting these Rev's up, plus with just + they have no - to create any spring type of reaction.
changing in 5 psi amounts does nothing either, as you probably lose that 5psi when you disconnect the pump lol.

hmm -ok - been doing some more reading and quick testing. With 90 PSI in both +/- chambers I get the requisite 20% sag or so as a starting point. I've set the rebound for now about 7 clicks from the rabbit (which is about 1/3 of the way thru the dial).

But I am still struggling to get much more than about 100mm of travel even pumping the bike up and down fairly hard - albeit stationary and not out on the "trail". Any less PSI and the sag starts increase but I do start to get more travel, but the sag at the start is about 40mm of the 150mm available which I think is to much.

"andy" · 3 Apr 2011 at 18:56

KnightStalker said:
changing in 5 psi amounts does nothing either, as you probably lose that 5psi when you disconnect the pump lol.

get a decent pump !
but the problems you two are discussing ive had with every pair of air forks ive ever owned

only time i ever remember getting some to feel how i wanted was messing with thicker oils and shim stacks

ichabod crane · 3 Apr 2011 at 18:59

booyaka said:
hmm -ok - been doing some more reading and quick testing. With 90 PSI in both +/- chambers I get the requisite 20% sag or so as a starting point. I've set the rebound for now about 7 clicks from the rabbit (which is about 1/3 of the way thru the dial).

But I am still struggling to get much more than about 100mm of travel even pumping the bike up and down fairly hard - albeit stationary and not out on the "trail". Any less PSI and the sag starts increase but I do start to get more travel, but the sag at the start is about 40mm of the 150mm available which I think is to much.

How to set up Rockshox dual air forks

KnightStalker · 3 Apr 2011 at 19:05

"andy" said:
get a decent pump !
but the problems you two are discussing ive had with every pair of air forks ive ever owned

only time i ever remember getting some to feel how i wanted was messing with thicker oils and shim stacks

Im currently using the Rockshox pump, but ive also used a Topeak one, neither of which really made a difference in small psi tuning to my feeling anyway.

Richie · 3 Apr 2011 at 19:09

I swear one of these times that I go out to find some trails I will come back without sodden feet... Damn you OS maps for stating there was a trail/path there when all I got was bog and trees

On the plus side, found some XC trails right beside my folks new place so I can stop in for lunch in comfort

booyaka · 3 Apr 2011 at 19:15

ichabod crane said:
How to set up Rockshox dual air forks

cheers for that - another way to try it by the looks of things!!

I appreciate it is trial and error but it's the HUGE difference between the Rockshox stated PSI's that are supposed to be used, and the ones that I appear to be moving towards that is slightly concerning me

robj20 · 3 Apr 2011 at 20:10

You wont be loosing pressure when you disconnect the pump, unless there is something wrong with the valve on the forks, you will however drop the pressure slightly when you reconnect the pump.

mistercrabb · 3 Apr 2011 at 21:19

robj20 said:
You wont be loosing pressure when you disconnect the pump, unless there is something wrong with the valve on the forks, you will however drop the pressure slightly when you reconnect the pump.

This, the hissing sound when you disconnect is the pressure in the pump's hose, not the shock.

6thElement · 3 Apr 2011 at 22:21

booyaka said:
But I am still struggling to get much more than about 100mm of travel even pumping the bike up and down fairly hard - albeit stationary and not out on the "trail".

That's why you need to ride and see how much travel you've used after riding. Set your sag, then ride to see if you're getting full travel after doing a decent ride with drops, rock gardens etc. Bouncing up and down while stationary will do fa.

Sag should normally be about 25% of travel, so you should be getting 38mm on your 150mm travel fork.

weescott · 3 Apr 2011 at 22:26

Random trail shot.

Abraichan red trail.

Slippery when wet? :eek:

booyaka · 3 Apr 2011 at 22:55

6thElement said:
That's why you need to ride and see how much travel you've used after riding. Set your sag, then ride to see if you're getting full travel after doing a decent ride with drops, rock gardens etc. Bouncing up and down while stationary will do fa.

Sag should normally be about 25% of travel, so you should be getting 38mm on your 150mm travel fork.

cheers - i appreciate that bouncing up and down will do nothing but just trying to get a rough guide as there seemed to be a lot of conflicting ways of setting things up!