Mountain Bike Reviews Forum banner

1 - 20 of 24 Posts

·
Registered
Joined
·
434 Posts
Discussion Starter · #1 ·
can i put a reba 29er lowers on a regular pike????

the pike is dual air couple years old and the reba 29er lowers are 09 with a through axel....

ive taken apart both a reba and a pike to change oil and change the travel (old reba)

am i crazy??? would that just reduce the 140 travel of the pike to 110?
 

·
carpe mañana
Joined
·
7,293 Posts
The uppers of the Pike are a little longer than the Reba uppers, I believe. If you were to just swap lowers, you'd wind up with two forks with roughly unchanged travel, yet, you'd have a different amount of bushing overlap in either. If you were to change the air pistons (the air piston of the 29er is longer than the one of a 26er) as well as the rebound assemblies you'd likely wind up with a longer travel Reba and a shorter travel Pike.

Let me know what you get for results. (I'm not sure the above is going to work out as I think).

_MK
 

·
Registered
Joined
·
10,039 Posts
The lowers are a lot longer on the 29er fork though, enough that a 120mm Reba 29er is actually a longer axle to crown than a 140mm Pike. So i think the OP is correct that bolting the 29er lowers onto the Pike would mean having to reduce the travel to 110mm or so
 

·
carpe mañana
Joined
·
7,293 Posts
boomn said:
The lowers are a lot longer on the 29er fork though, enough that a 120mm Reba 29er is actually a longer axle to crown than a 140mm Pike. So i think the OP is correct that bolting the 29er lowers onto the Pike would mean having to reduce the travel to 110mm or so
One thing I know for a fact, as I just had a set of Reba uppers warrantied, is that the 29er and 26er Reba uppers are identical. The extra length is accommodated by a longer air shaft piston on the dual air, for example, which leads me to believe the rebound shaft is also longer by the same amount.

_MK
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #5 ·
thanks

"The uppers of the Pike are a little longer than the Reba uppers, I believe. If you were to just swap lowers, you'd wind up with two forks with roughly unchanged travel, yet, you'd have a different amount of bushing overlap in either. If you were to change the air pistons (the air piston of the 29er is longer than the one of a 26er) as well as the rebound assemblies you'd likely wind up with a longer travel Reba and a shorter travel Pike."

thats what im thinking..... do you think the lowers on a reba 29er are actually longer than a regular reba? or do they just extend the arch in between the lowers to fit the bigger wheel?

can anyone out there measure their reba 29er lower for me? from the bottom of the lower to the seal?

i think a little math and i could have this thing figured out.....

pike :

lowers from bottom to seal = 11.75 inches
air side = 20 inches

proves nothing until i know the reba 29er measurements.... why is nothing technical listed on srams website concerning the 29ers yet?

and one more thing....

the offset is measure from the wheel position / center of the hub right?

so it wont matter what the pike's offset is, if i use the reba lower, the offset will be whatever the reba is,,,,, right?

pike = 42
reba 29er = 46?
 

·
carpe mañana
Joined
·
7,293 Posts
nicolicious said:
do you think the lowers on a reba 29er are actually longer than a regular reba? or do they just extend the arch in between the lowers to fit the bigger wheel
They lowers must be longer as the air piston for the dual air is longer for the 29er than a 26er. I could measure the difference as I have both sitting in my parts bin.

Also, if you'll be thinking about selling the reduced travel Pike, let me know as I have an application for one. :)

_MK
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #7 ·
damn.....

well boom.... 100mm is what im looking for so that sounds good but what mk said might have just thrown a monkey wrench in it.....

or maybe not.... dammit....

yea, mk if you dont mind measuring the two forks that would be excellent...


and as of now im am trying to sell the pike for a 29er fork but no bites yet.... and i found a reba 29 lower for cheap so im trying to do what i can for little money...

the pike is in the classifieds... original that is...
 

·
carpe mañana
Joined
·
7,293 Posts
nicolicious said:
well boom.... 100mm is what im looking for so that sounds good but what mk said might have just thrown a monkey wrench in it.....

or maybe not.... dammit....

yea, mk if you dont mind measuring the two forks that would be excellent...


and as of now im am trying to sell the pike for a 29er fork but no bites yet.... and i found a reba 29 lower for cheap so im trying to do what i can for little money...

the pike is in the classifieds... original that is...
Gotcha. I was thinking you had both and were going to do the surgery. I would have been interested in the "short travel" Pike, as I'd like to run a throughaxle on my singlespeed. I'll take the measurements this evening for ya. I may be interested in just the Pike lowers, also.

_MK
 

·
Registered
Joined
·
2,029 Posts
nicolicious said:
"The uppers of the Pike are a little longer than the Reba uppers, I believe. If you were to just swap lowers, you'd wind up with two forks with roughly unchanged travel, yet, you'd have a different amount of bushing overlap in either. If you were to change the air pistons (the air piston of the 29er is longer than the one of a 26er) as well as the rebound assemblies you'd likely wind up with a longer travel Reba and a shorter travel Pike."

thats what im thinking..... do you think the lowers on a reba 29er are actually longer than a regular reba? or do they just extend the arch in between the lowers to fit the bigger wheel?

can anyone out there measure their reba 29er lower for me? from the bottom of the lower to the seal?

i think a little math and i could have this thing figured out.....

pike :

lowers from bottom to seal = 11.75 inches
air side = 20 inches

proves nothing until i know the reba 29er measurements.... why is nothing technical listed on srams website concerning the 29ers yet?

and one more thing....

the offset is measure from the wheel position / center of the hub right?

so it wont matter what the pike's offset is, if i use the reba lower, the offset will be whatever the reba is,,,,, right?

pike = 42
reba 29er = 46?
There is plenty of info on the RS site to figure this out. The 2010 parts document lists all of the parts (exploded diagrams) of all forks/shocks/etc. You can compare part numbers to determine if parts are indeed different, or the same part is being used in different applications (somthing that RS does a lot of).

There are also engineering drawings of forks availalble under the 'user specs and standards' heading. The tora 29er is the same chassis dimentionally as the reba 29.

Offset can come from either lower design, or from crown design, or a combination of both.
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #11 ·
sounds too good to be true.... someone smart check my math?

thanks to davep - i found the techspecs for the reba 29er (although not the thru axel version and not the reba at all, but the tora29 which should be the same dimensions) and the 07 pike i have.....

pike axel to crown = 355mm

reba axel to crown = 381mm

these lengths are the length of the lowers.... and reba has a +26mm

pike upper = 518mm (length from race to bottom of leg where bolt goes on the air side....i hope this is the length of the air assembly, or at least how much is need to hold the upper and lowers together)

reba upper = 512mm (again, length from race to bottom of leg where bolt attaches...)

god dammit.... brain fart.... what the hell am i doing..... oh yea.. .. see if this logic is rational.....

if a reba 29er has 100mm of travel with the

512(uppers) + 381(lowers) = 100mm of travel

and a pike uppers of 518mm was sub'd in for the reba uppers

518(p. upper) + 381 (r. lowers) = 100mm of travel (+/-3 or 4mm)

.................

or should i just wait till my pike sells and buy a used real 29er fork????

im kind of attached to this pike bc i know where its been and how its been used.....

any one else sketched out from buying a used fork???

...........................
 

·
carpe mañana
Joined
·
7,293 Posts
I'm measuring the difference between the 29er Reba air shaft and 26er Reba air shaft to be 31mm.

_MK
 

·
carpe mañana
Joined
·
7,293 Posts
Hey, I looked up the numbers:
(a2c list: http://www.sram.com/_media/techdocs/MY2010 Crown to Axle.pdf)

Here is my take on it:

Reba 29er a2c is 506mm @ 100mm; 526 @ 120mm.
Reba 26er a2c is 473mm @ 100mm; 493 @ 120mm.

a2c difference is 33mm. I measured 31, but I may have been a little off on the alignment of the two shafts.

Pike a2c is 518 @ 140mm.
Theoretical a2c of a Reba 26er at 140mm is 513mm. 5mm difference.

If you were to put Reba 29er lower onto a Reba 26er you'd likely observe a reduction of travel of about 33mm.

Doing the same to the Pike you'd observe a 33mm change in a2c, however, the 5mm in question could be extra stanchion length or crown height or due to difference in the lower. That means that you'd either get a 107mm fork with a2c 5mm higher than stock Reba 29er or 112mm fork with a2c 5mm higher than the stock Reba 29er (set to that travel).

_MK
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #14 ·
last question i swear......

what about the fork offset?

ive checked google and rockshox and this website for the answer:

how does rockshox measure fork offset?

the pike has a 38mm and the reba having a 46 what will that make my frankenfork?

38 or 46?

anyone out there know where its measured from?

a2c would be great bc than it would take on the rebas offset of 46.....

if its measured another way i have really no clue what it would be.... thanks
 

·
carpe mañana
Joined
·
7,293 Posts
Reba 26er has an offset of 39 (QR). Reba 29er is +7mm.
Pike is 42mm.

I would stipulate that with the 29er lowers on the Pike you'd have 46-48mm offset.

_MK
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #16 ·
wow, dyslexia is hard to live with....

thanks mk..... i swear when i read the a2c and offset page it said pike was a 38.... but after rechecking ..... 42,.....

ok... wish me luck .....
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #17 ·
fork update - almost.....

got my reba lowers today in the mail.... thanks mike....

and to my surprise there is a false bottom..... but that only is a problem if i want to do anything to the bottom of the fork.... like changing the rebound or adding air.... kind of a *****... but nothing needle nose pliers cant handle....

its about 1.5 inches to the air or rebound.... might invest in the reba 29er air spring some day when i have 60 bucks burning a hole in my pocket....

and i did have to go out and get a set of 'deep' nut drivers to screw on the right side....

sorry i didnt take any pic of the installation.... its the same a usual install....

air is at 100 neg, 115 positive....

anyone know how much oil you use in a 29er? i just used what sram suggest for the regular pike.....

and im still waiting on a new head set to test this sucker out.... that universal cycles.....where 3 days shipping means half your stuff is 3 days and the other half is ground.... thats another topic though...

i get somewhere in between 80-85mm of travel.... ill let you know when i get the headset on if it falls apart at santos this weekend
 

Attachments

·
carpe mañana
Joined
·
7,293 Posts
nicolicious said:
got my reba lowers today in the mail.... thanks mike....

and to my surprise there is a false bottom..... but that only is a problem if i want to do anything to the bottom of the fork.... like changing the rebound or adding air.... kind of a *****... but nothing needle nose pliers cant handle....

its about 1.5 inches to the air or rebound.... might invest in the reba 29er air spring some day when i have 60 bucks burning a hole in my pocket....

and i did have to go out and get a set of 'deep' nut drivers to screw on the right side....

sorry i didnt take any pic of the installation.... its the same a usual install....

air is at 100 neg, 115 positive....

anyone know how much oil you use in a 29er? i just used what sram suggest for the regular pike.....

and im still waiting on a new head set to test this sucker out.... that universal cycles.....where 3 days shipping means half your stuff is 3 days and the other half is ground.... thats another topic though...

i get somewhere in between 80-85mm of travel.... ill let you know when i get the headset on if it falls apart at santos this weekend
I do have a spare air spring for the 29er. Will the rebound rod get in the way of getting full travel with the 29er air piston?

_MK
 

·
Registered
Joined
·
434 Posts
Discussion Starter · #19 ·
****.... whats a rebound rod?

ill go check srams website for the rebound rod....

what air spring do you have? reba 29er????? are the o - rings still good?

cause funny thing is - in my rush to dismantle my pike i stripped the hell out of threads....

i forgot to bring the nut down to even and couldn't find my plastic mallet either.... to tap the air side free..... but i got some very small flat head screw drivers and bent them back to usable state... but let me tell you, it took me about 15 mins to screw on the fork pump to the neg side....
 

·
carpe mañana
Joined
·
7,293 Posts
nicolicious said:
ill go check srams website for the rebound rod....

what air spring do you have? reba 29er????? are the o - rings still good?

cause funny thing is - in my rush to dismantle my pike i stripped the hell out of threads....

i forgot to bring the nut down to even and couldn't find my plastic mallet either.... to tap the air side free..... but i got some very small flat head screw drivers and bent them back to usable state... but let me tell you, it took me about 15 mins to screw on the fork pump to the neg side....
The rebound rod is much like what you have on the air spring side but for the rebound. The motion control sits on top and it all handles compression. On the bottom you have a rod with an orifice the oil cycles through on rebound. The shaft goes through the opening on the bottom of the stanchion like the air shaft does.

My 29er air shaft is brand new.

_MK
 
1 - 20 of 24 Posts
Top