# Rear shock size for Bighit 06 question - 8.5 vs 8.75 - Xpost



## robicycle (Nov 5, 2007)

Hi , I would like to swap my old Vanila coil for new Mazocchi Roco RC WC. Well to be honest I do not understand shock sizes. Specialized web specs says that Fox Vanilla coil 8.75x2.5" 190mm travel and I found good deal on Marzocchi Roco RC WC coil but it is 8.5x2.5" . Please can anybody explain to me , what is difference... can I use this Marzocchi shock on my Bighit?? Will I keep same travel? Thank you very much for your help . Rob


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## JOURNEYC6 (Jun 7, 2008)

First number is for the size/lenght of the shock messured from eye to eye. Your new shock will be 0.25 inches shorter than your old shock.
Second number is the stroke/travel of the shock, same stroke on both shocks 2.5
Note: stroke or travel of the shock is not the same as the real travel of your back wheel.
With the new shock your bike will seat 0.25 inches closer to the ground, to me no biggie.


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## LDH (May 27, 2007)

you will be fine , you can also use the upper shock mount on the link and keep the same angles.


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## mrpercussive (Apr 4, 2006)

LDH said:


> you will be fine , you can also use the upper shock mount on the link and keep the same angles.


whoa... havent seen you in hella long less... how's it goign?


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## LDH (May 27, 2007)

mrpercussive said:


> whoa... havent seen you in hella long less... how's it goign?


I am still on here everyday but don't post as much. The Fresno crew is doing fine, I put some new bikes together for Alyssa , Matt and Me so we are ready for cccx to get going again. I will start a new thread in the Nor-cal forum to show them off. Oz has been riding his heavy ht in a local CX series and doing well so he is going to be a lot stronger for next years series. Matt won the u-18 boys Springville XC race on his first time out on the Heckler so he should be faster too so i better start riding more. I did build up a killer Super-D weapon for myself to help close the gap. Ride safe,Les


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## SHIVER ME TIMBERS (Jan 12, 2004)

.25 doesn't seem like much for eye to eye...personally I wouldn't do it.....whats the level ratio on that bike?? I think it is pretty close to 3:1 meaning you will lose about 3/4 of an inch of travel....

I wouldn't give up more then 3/4 of an inch of travel...matter how cheap you can get the new shock


what I would do is call push industries and ask about your shock....is it an Vanilla RC or Vanilla R....what shock do you have


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## mrpercussive (Apr 4, 2006)

LDH said:


> I am still on here everyday but don't post as much. The Fresno crew is doing fine, I put some new bikes together for Alyssa , Matt and Me so we are ready for cccx to get going again. I will start a new thread in the Nor-cal forum to show them off. Oz has been riding his heavy ht in a local CX series and doing well so he is going to be a lot stronger for next years series. Matt won the u-18 boys Springville XC race on his first time out on the Heckler so he should be faster too so i better start riding more. I did build up a killer Super-D weapon for myself to help close the gap. Ride safe,Les


good to hear things are going well... hopefully i'll see you out there soon... :thumbsup:


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## LDH (May 27, 2007)

both shocks he is refering to have the same 2.5" stroke so travel will be the same (good match for most forks) and the .25" shorter e to e length does give more tuning options. I have fitted 8.5" shocks to a couple of big hits for a few kids that ride with my son.


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## damion (Jun 27, 2003)

*I agree.*



SHIVER ME TIMBERS said:


> .25 doesn't seem like much for eye to eye...personally I wouldn't do it.....whats the level ratio on that bike?? I think it is pretty close to 3:1 meaning you will lose about 3/4 of an inch of travel....
> 
> I wouldn't give up more then 3/4 of an inch of travel...matter how cheap you can get the new shock
> 
> what I would do is call push industries and ask about your shock....is it an Vanilla RC or Vanilla R....what shock do you have


It sounds like the OP is talking about a shorter shock, with a shorter stroke. If that is right, I say NOT A CHANCE.

I would not give up 3/4" , no matter the deal. Just have the stocker PUSHed.


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## PCinSC (Oct 25, 2005)

Which model Big Hit do you have? What fork are you running? And which frame shock mount are you currently using: high (68*) or low (66*)?

The Big Hits of '06 and '07 came with either a 8.75" x 2.75" shock or a 8.75" x 2.5" shock, depending on which model Big Hit you have. If you go to a 8.5" x 2.5" shock it will slacken the angles of the bike and lower the bottom bracket height. Also, it's possible the rear tire will contact the seat mast at full travel. If your bike currently has a 2.5" stroke shock then you shouldn't lose any travel, if its got a 2.75" stroke shock you will lose ~18mm of travel.

Using the second mounting hole on the link may return the geometry to "normal" (normal will depend on your starting point) and avoid some of these problems...have you actually successfully tried this LDH?



robicycle said:


> Hi , I would like to swap my old Vanila coil for new Mazocchi Roco RC WC. Well to be honest I do not understand shock sizes. Specialized web specs says that Fox Vanilla coil 8.75x2.5" 190mm travel and I found good deal on Marzocchi Roco RC WC coil but it is 8.5x2.5" . Please can anybody explain to me , what is difference... can I use this Marzocchi shock on my Bighit?? Will I keep same travel? Thank you very much for your help . Rob


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## robicycle (Nov 5, 2007)

Thank you guys for all your input. My Bighit is 06 FSR II and it has Fox Vanilla R 8.75x2.5" rear shock.So far there is nothing wrong with original shock. Last year I got good deal on Marzocchi 888 RC2XVA and I love this fork and this year I wanted to ask Santa for new rear shock and I want Marzocchi Roco RC WC. I found I think good deal HERE but they have only 8.5x2.5" size . I do not want to lower my Bighit or get less travel.First of all I did not know what these numbers mean so thank you for explaining to me and than I looked at specs for FSR III and found out that I should look for 8.75x2.75 if I want to match my fork and upgrade something. Case closed , I just need to find some good price. One question I would have - there are two positions to mount shock on frame. Originaly shock was mounted on position marked "SLACK" and I wonder what is that other position "STEEP" for. Thank you for all of your help. Rob


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## PCinSC (Oct 25, 2005)

There are lots of 8.75" x 2.75" shocks out on the used market, take a look around on Ebay and on the MTBR classifieds. Going to this shock size from what you currently have may actually steepen the bike a little bit and raise the BB a smidge, I doubt it'd be a huge deal. *Edit:* Nevermind that last statement, I re-read your post and you've already got the 8.75" length so geometry shouldn't change, just the amount of travel.

The slack setting should get you a 66* head angle, the steep setting will be around two degrees steeper with a higher BB height. I'm not really sure why the steep setting is even there because I sure wouldn't want to got downhilling with a 68* HTA and 15.25"+ BB height.

I've got an '07 Big Hit with an 888 up front and the big shock and it is a pretty good combo.


robicycle said:


> Thank you guys for all your input. My Bighit is 06 FSR II and it has Fox Vanilla R 8.75x2.5" rear shock.So far there is nothing wrong with original shock. Last year I got good deal on Marzocchi 888 RC2XVA and I love this fork and this year I wanted to ask Santa for new rear shock and I want Marzocchi Roco RC WC. I found I think good deal HERE but they have only 8.5x2.5" size . I do not want to lower my Bighit or get less travel.First of all I did not know what these numbers mean so thank you for explaining to me and than I looked at specs for FSR III and found out that I should look for 8.75x2.75 if I want to match my fork and upgrade something. Case closed , I just need to find some good price. One question I would have - there are two positions to mount shock on frame. Originaly shock was mounted on position marked "SLACK" and I wonder what is that other position "STEEP" for. Thank you for all of your help. Rob


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## tjneutral (Nov 22, 2008)

Hello everybody,

i have a big hit 1 2008 and i put a roco tst r 8,75X2,75 on it.

The problem is that the suspension only fits in steep position (the upper one) and the tank touches the bottom of the shock link.
Does anybody runs one of them on bighits?
Does the rear shock link changes from model 1 to 3 or the fox dhx 5 that cames with No3 is a little more smaller than roco(or smaller tank)??


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## HTFR (Jan 11, 2007)

robicycle said:


> Hi , I would like to swap my old Vanila coil for new Mazocchi Roco RC WC. Well to be honest I do not understand shock sizes. Specialized web specs says that Fox Vanilla coil 8.75x2.5" 190mm travel and I found good deal on Marzocchi Roco RC WC coil but it is 8.5x2.5" . Please can anybody explain to me , what is difference... can I use this Marzocchi shock on my Bighit?? Will I keep same travel? Thank you very much for your help . Rob


The 8.75 and 8.5 mesurment is the eye 2 eye of the shock (length). the 2.5 mesurment is how much the shock compresses (stroke). Switching to the 8.5 I2I should be fine if you have a high bottom bracket/Low bottom bracket options for mounting the shock. The only catch is, due to clearance, you will probably have to run the shock in the High bottom bracket position. The bike will ride like it is in the "slack" or low bottom bracket shock position, because the shock is shorter. If you want to check to see if the shock will work in the low bottom bracket position, remove the spring from the shock, mount the shock in the low bottom bracket or "slack" position, and compress the suspetion by sitting on the bike. when you reach the point of bottoming out, check if there is any frame, linkage, shock body contact with anything. If the only thing causing the bottom out is the shock being fully compressed you can run it in the Low bottombracket / "slack" position.

Because the stroke of both shocks is 2.5 you will not loose any travel.


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## robicycle (Nov 5, 2007)

tjneutral said:


> Hello everybody,
> 
> i have a big hit 1 2008 and i put a roco tst r 8,75X2,75 on it.
> 
> ...


Ooops , I just placed order for mine roco wc same size for my bighit 06. I hope mine will fit. Did you contact dealer or Marzocchi? - there is sticky thread at "Shock and suspension forum" named "Marzocchi support here" - I would try to ask there , what you can do. I do not feel like run roco on steep is good idea. Sorry that I could not help more. Rob


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## tjneutral (Nov 22, 2008)

Sorry my friend but somebody else told me the same thing.
Change it for a fox.. I will do the same .

Too bad for the money.


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## tjneutral (Nov 22, 2008)

tjneutral said:


> Sorry my friend but somebody else told me the same thing.
> Change it for a fox.. I will do the same .
> 
> Too bad for the money.


Sorry i've just read on another forum that somebody else is running a wc on 2006 bighit.
Maybe Differences on bighit models or roco models. Good for you, it's a great shock.

Sorry for the trouble.


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## turbodog (Feb 28, 2004)

Well......I've got a 2006 bighit I, size medium, and I'd like to put a 8.5x2.5 Roco Air TST R on it. Want the shorter shock length, am ok with the travel. Any chance it will fit, or am out of luck?

I've sent a PM to "marzocchi tech support" asking for his advice or a drawing....


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## tjneutral (Nov 22, 2008)

turbodog said:


> Well......I've got a 2006 bighit I, size medium, and I'd like to put a 8.5x2.5 Roco Air TST R on it. Want the shorter shock length, am ok with the travel. Any chance it will fit, or am out of luck?
> 
> I've sent a PM to "marzocchi tech support" asking for his advice or a drawing....


I'm sure it will fit but why you want a shorter shock?????!!!!! (I don't know if you have it already).
I don't know if the link reaches it's end of travel with a shorter shock better go for a 8,75...


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## turbodog (Feb 28, 2004)

tjneutral said:


> I'm sure it will fit but why you want a shorter shock?????!!!!! (I don't know if you have it already).
> I don't know if the link reaches it's end of travel with a shorter shock better go for a 8,75...


Um....to slack the bike out. Thanks.


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## turbodog (Feb 28, 2004)

tjneutral said:


> I'm sure it will fit but why you want a shorter shock?????!!!!! (I don't know if you have it already).
> I don't know if the link reaches it's end of travel with a shorter shock better go for a 8,75...


What makes you think it will fit? Did you get yours to fit?

I'm going with the 8.5x2.5 because it will drop the BB and slacken the HA. I already ride the bike all around in the "slack" setting. I want to be able to ride all around in the steep setting, and use slack for some DH. I don't care about giving up a bit of travel....I've got the stock 8.75x2.5 right now anyway.

The 8.5x2.5 shock should fit on a bike almost exactly like a 8.75x2.75, except it will be shorter when fully extended. It will have the same interference issues when fully compressed.


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## turbodog (Feb 28, 2004)

Bump, still looking for a firm answer.....!


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## robicycle (Nov 5, 2007)

Done , Marzocchi Roco Wc 8.75x2.75 , Ti spring later. Can't wait to ride.... I have to wait couple more months


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## turbodog (Feb 28, 2004)

Cool, thanks for posting pics!!!

Have you checked that at bottom out....? It looks like the shock piggyback will come very close to the bottom of the seatmast, infact it looks like it will easily hit it. 

On the bighits that come with a piggy back shock stock, the piggyback is flipped down...is there room for it that way...?


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## robicycle (Nov 5, 2007)

well turbodog , in theory it should be fine , but you are right - I did not check bottom out position and I am stupid indeed. I was in bikeshop to let them mount my shock and they told me about nightmare to get spring on/off shock - they say that I need some special tool to compress spring in order to remove it. Now I am looking at it , I feel like I should check it. When I measure travel and distance piggyback-frame , shock should stop like a hair before frame - it may not be OK :nono: I will go back to my LBS and let them check it. BTW there is NO way to mount it with piggyback down - there is no room...... Thanks for warning - Rob


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## turbodog (Feb 28, 2004)

robicycle said:


> BTW there is NO way to mount it with piggyback down - there is no room...... Thanks for warning - Rob


Hummmmmmmmmmmm......you tried it? I thought I saw pics from tjneutral showing that, but he could only use the "steep" position. Do you know if it was somewhat close, or not a chance?

Would I have better luck with the shorter 8.5" shock, because the link has mooved up a bit creating more room?

I'm also concerned about the air valve on the Roco air, if I mounted the shock like yours, the valve would be forward of where the shock mounts to the link and probably not clear it...

Thanks!


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## turbodog (Feb 28, 2004)

robicycle said:


> Now I am looking at it , I feel like I should check it. When I measure travel and distance piggyback-frame , shock should stop like a hair before frame - it may not be OK :nono: I


You could just try unscrewing the sping collar as far as possible, and then sit on the bike and see how far that gets out compressed, and try measuring from there. The shock is going to pivot up as it compresses.


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## turbodog (Feb 28, 2004)

robicycle said:


> well turbodog , in theory it should be fine , but you are right - I did not check bottom out position and I am stupid indeed. I was in bikeshop to let them mount my shock and they told me about nightmare to get spring on/off shock - they say that I need some special tool to compress spring in order to remove it. Now I am looking at it , I feel like I should check it. *When I measure travel and distance piggyback-frame , shock should stop like a hair before frame - it may not be OK *:nono: I will go back to my LBS and let them check it. BTW there is NO way to mount it with piggyback down - there is no room...... Thanks for warning - Rob


I made some measurements off the sideview pic, and after adjusting for the shock angle, I am 95% sure the piggyback will hit, inside the seatmast, at FULL 2.75" compression. Considering there's a bottom out bumper, it may be OK.....but I would certainly go to the effort of getting it checked for real before jumping off anything.....


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## robicycle (Nov 5, 2007)

Hi turbodog - it may fit at steep position but not a chance in slack position....I don't think that I want to ride my bike in steep position - I am not sure about steep settings - what it will do?? This was the only way to mount it on my frame in slack position. I would say to all who wants to mount new Rocco on Bighit - do not get Rocco - fit is too tight , I am not able to unscrew spring collar all the way down and I just hope that piggyback will not hit frame fully compressed. I am going to my LBS tomorrow (it will be sleepless night) , I want them to remove spring , mount shock on frame and fully compress shock - we will see..... I measured 2 1/4" between bumper and shock body , that is exactly distance between piggyback and frame  As your Rocco Air - I am not sure how big this shock is , but as I am looking at picture - there is air valve for shock pump and I think that is your big problem. It sucks that I can not mount Marzocchi shock on my frame - I wanted to match my 888 fork (which I am in love). Any news from Marzocchi tech support?? Thanks again for warning - I will be back tomorrow pm with more info. Rob


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## Bent Wheel (Oct 6, 2007)

Yes, be careful with the piggy back being up. My son sold his BH to a guy who turned the shock around and proceeded to tear the PB off. Measure twice, break it 0 times.


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## robicycle (Nov 5, 2007)

Just small update , I was looking around and tjneutral is selling his Rocco , he switched to Vanilla - he say shock will not fit....... I am ready to shoot myself.
hey skip canfield - did you have Rocco on your bighit?? any pics.? Thanks Rob

link:http://www.pinkbike.com/forum/listcomments/?threadid=62740&pagenum=1#commentid1397179


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## Bent Wheel (Oct 6, 2007)

robicycle said:


> Just small update , I was looking around and tjneutral is selling his Rocco , he switched to Vanilla - he say shock will not fit....... I am ready to shoot myself.
> hey skip canfield - did you have Rocco on your bighit?? any pics.? Thanks Rob
> 
> link:http://www.pinkbike.com/forum/listcomments/?threadid=62740&pagenum=1#commentid1397179


No, it was a Risse J5 coil, sorry no pics.


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## turbodog (Feb 28, 2004)

Well....I called marzocchi USA today and the tech gave me a few dimensions over the phone....it SEEMed like it would fit based on what I measured, but who knows. I do like the looks of this pic, however....










That's the EXACT frame I have, a medium 2006 bighit 1. So if he can fit a 8.75" shock on there, and the piggy backs are the same, I should be able to squeeze a 8.5" rocco air onto it. Think I'm going to go for it.


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## turbodog (Feb 28, 2004)

robicycle said:


> Hi turbodog -* it may fit at steep position but not a chance in slack position....*I don't think that I want to ride my bike in steep position - I am not sure about steep settings - what it will do?? This was the only way to mount it on my frame in slack position.


Are you 110% sure of this....did you try it yourself? Based on the pics on pinkbike, it looks like it fits, but just barely. I would flip it around and try the slack posititon...


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## robicycle (Nov 5, 2007)

turbodog said:


> Well....I called marzocchi USA today and the tech gave me a few dimensions over the phone....it SEEMed like it would fit based on what I measured, but who knows. I do like the looks of this pic, however....
> 
> 
> 
> ...


Turbodog , this is BS!! I have 06 medium frame and I just wanted to flip my shock - THERE IS NO WAY , I am missing like 1" (distance between slack mount and shock mount) I can post pics. I do not know how he made it fit... Recently , I am trying take spring off , I have to try this before I go to bed.....be back


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## turbodog (Feb 28, 2004)

robicycle said:


> Turbodog , this is BS!! I have 06 medium frame and I just wanted to flip my shock - THERE IS NO WAY , I am missing like 1" (distance between slack mount and shock mount) I can post pics. I do not know how he made it fit... Recently , I am trying take spring off , I have to try this before I go to bed.....be back


Well, I'm scratching my head then........:madman:

Try mounting the shock, as pictured above on the grey bike, very carefully in this order:

- loosen the spring so there is some free play in it.

- mount the shock at the upper mount, to the frame, push it upwards while you do this

- slightly compress the shock (the free play amount)

- compress the rear suspension of the bike, more than the shock

- work the lower shock mount into the swing-link from the bottom, and bolt in place.

- allow to extend VERY carefully, while checking for interference.

If that doesn't work......wellll....


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## robicycle (Nov 5, 2007)

turbodog said:


> Well, I'm scratching my head then........:madman:
> 
> Try mounting the shock, as pictured above on the grey bike, very carefully in this order:
> 
> ...


OK , I gave up.... there is no way to loosen the spring so you can actualy remove spring. My LBS told me about this , they have small tool to compress spring and then remove it. I will go to see them tomorrow. Turbodog , you may be lucky with 8.5 shock lenght , I may see to fit this shock in with piggy down, but I have 8.75 because I wanted 8 inches in rear... If I would follow your setup , I would have to compress my shock (not sure how-there is no free play) , it would maybe fit but I would not get all travel.... Lets see tomorrow , I will post as soon as I will be done there. Please wish me luck... Rob


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## robicycle (Nov 5, 2007)

End of story. Marzocchi 09 Rocco WC 8.75x2.75 WILL NOT FIT TO 06 BigHit medium frame. I learned hard way , thank you Turbodog for warning , I could jump that shock and it would be destroyed. Anybody interested in brand new never used Marzocchi Rocco 09 WC 8.75x2.75 + 500lb spring please PM me with your offer. I will post it in classifieds and on Ebay today pm. Thanks for all of your help guys. Rob


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## turbodog (Feb 28, 2004)

Just a quick followup.....got the 8.5x2.5 Rocco Air TST R last night and fitted it to my bike. It fits fine in the "steep" position, but as robicycle noted, the valve interferes and I had to install it without the cap (need a thinner cap). My geometry hasn't changed at all from running the 8.75" in the slack position. Shock feels VERY nice.

The new shock won't fit at all in the slack position, because the valve stem hits the bulged portion of the link where the mounting bolt is. I think if it could be fitted with some sort of shorter or 90 degree valve, it would fit ok....might see who can do that.


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