[HowTo] do the wedge seat/post mod

[bmxmadness]

In order to do the wedge seat post mod you have to have a pivatol seat/post set up.

The first step in doing this mod is find an old 1 threaded headset bolt and a 1 1/8 inch wedge make sure your bolt is long enough to get all the way through the seat and post and still has enough to tighten the wedge.



cut the seat post as close the same angle as you can get. be precise with this and take your time. file the post down so that nothing sharp or stray will get in the way of the wedge and the post.






next, in the pivatol seats there is a bolt that comes stock that threads into the post. you are gonna need to pound that bolt out. dont be worried about hurting anything in the seat guts. just get it out of there, no matter what it takes.

the next thing to do is push the new bolt through the seat



put the post up to the seat just like you normally would but thread your wegde on just enough to keep it from spinning in the frame when you try and tighten it. but not so tight that you have to force it into the seat tube




when you tighten the post and seat into the frame make sure that you just get it tight enough to hold it in place DO NOT over tighten it or it may cause ovalization in the seat tube.

and there you have the pivatol seat mod! i hope this helped alot of you. its the best i can do. and this is my first ever how to

finished product:




here is a link for ppl in the uk that are having trouble getting ahold of a wedge

http://www.sjscycles.co.uk/product-S...wedge-6024.htm

[gtbmx0222]

nice how to.
i plan on doing this when i buy my macneil setup.

[gtbmx0222]

what kind of sprocket is that that youre running i like it alot.

[mstandlee]

So how do you tighten the bolt then once you have it installed? Nice how to, been waiting for this.

[Odysseus]

good how to...bitch

looks way better than it did with the old seatclamp. props. GET AN SL NOW!

[bmxmadness]

the sprocket is a 25t snafu lite i think. cant remember if thats what its really called or not

you tighten the bolt the same way you would as if you were just tightening the seat to the post. you just have to hold your seat at the right angle when you tighten it

[gtbmx0222]

oh well im might have to order that sprocket....how much was it?

[bmxmadness]

^^i cant remember i think around 25 or so

[KoolAidGuy]

i want to do this but im afraid ill mess up cutting the seatpost at an angle...

any tips on how to get a perfect or close to perfect cut?

[bmxmadness]

umm...what i did was put the post in a vice so i didnt have to hold on to it put the wedge on top of the uncut post and lined it up the best i could. i took a razor blade and made a mark of where to cut. just sawed slow till i got deep enough into the post to go fast and not slip.

i was a jsut a little bit off on the top of my cut but its nothing a little filing could fix

[blkbike]

damn good how to. looks clean

[sketchyC]

Very nice. I have been waiting for a review on how to do this. Now i just need to find that long bolt and a wedge. Thanks.

[screwglue]

can somone explain to me what this is for? and why? i dont understand...?

[bmxmadness]

i did it because i wanted to lower my seat even more and because no one around my area has done it...its different and it looks cool becasue there is no seat clamp (i think)

[screwglue]

ohhhh i didnt thof it that it works just like shadow bar ends do, does this work on a normal seatpost?

[blkbike]

ohhhh i didnt thof it that it works just like shadow bar ends do, does this work on a normal seatpost?

just the pivotal style posts. i.e macniel, redline, premium, ect... And yes it works just like a bar end

[jawn]

The wedge is 1", not 1.125" like you said. Quill stems only existed for 1" forks, which fits today's standard of 1" seat posts nicely :>

[rect won]

i have a question.why would want to do this to your seat..im so lost lol

[Busades]

Just to let you kids know in advanced this post mod completely voids your frames warranty (regardless of weather you cut the frames seat tube), and is actually potently very harmful to your frame.


Just a quick rundown:

Case 1:
You run the wedge below the top tube, causing the seat tube to expand or ovalize. Weges are very powerful, they can easily ovalize 0.9mm tubing.

Case 2:
You run the wedge inside the toptube and seat stay junction area. Running the wedge here seems like a good idea, but in fact you are applying a huge amount of stress on the welds on this already highly stressed junction. There is a good chance that under load, you can crack the welds in this area. Having the seat this high also applies more stress to the frame since the seat tube does not penetrate low enough into the seat tube.

In both cases you are also canceling out the triangulation in your frame due to the location your are clamping your seat at. Basically your toptube junction has now become a fulcrum for your seat post, allowing your seat post to apply pressure within the main triangle of your frame.

[dirkadirka]

awsome article man

[bmxmadness]

Just to let you kids know in advanced this post mod completely voids your frames warranty (regardless of weather you cut the frames seat tube), and is actually potently very harmful to your frame.


Just a quick rundown:

Case 1:
You run the wedge below the top tube, causing the seat tube to expand or ovalize. Weges are very powerful, they can easily ovalize 0.9mm tubing.

Case 2:
You run the wedge inside the toptube and seat stay junction area. Running the wedge here seems like a good idea, but in fact you are applying a huge amount of stress on the welds on this already highly stressed junction. There is a good chance that under load, you can crack the welds in this area. Having the seat this high also applies more stress to the frame since the seat tube does not penetrate low enough into the seat tube.

In both cases you are also canceling out the triangulation in your frame due to the location your are clamping your seat at. Basically your toptube junction has now become a fulcrum for your seat post, allowing your seat post to apply pressure within the main triangle of your frame.

actually it doesnt void the warranty of the frame..i contacted federal about it and they said that if i wouldnt have painted or cut my seat tube then i would still have a warranty..however i knew my warranty was voided and just did this for the sole purpose of proving you wrong...so before you go spoutin off idiotic comments that you have no idea about get your facts straight

putting the wedge on the weld is ridiculous anyone who knows anything about metal and welds is smarter enough to know that welds will most likely snap if to much pressure is applied...where i have the wedge is one of the less stressful places on the bike...like on the eastern's were the cut out is..its where my wedge is..so hardly any excess pressure is being applied

jawn-i have no idea what the hell your talking about

dirka dirka-thanks

[Busades]

actually it doesnt void the warranty of the frame..i contacted federal about it and they said that if i wouldnt have painted or cut my seat tube then i would still have a warranty..however i knew my warranty was voided and just did this for the sole purpose of proving you wrong...so before you go spoutin off idiotic comments that you have no idea about get your facts straight

Trust me man, I work in the industry, if I ever suspected a warrantied frame had this seat post in it, the warranty would be completely voided. Its happened, I have personally seen frames fail due to this mod. Just because your frame may not noticeably be harmed, its doesn't mean that it doesn't happen.


This same mod was done on mountain bikes many years ago, they ditched it. It was too heavy and was damaging the frames that they ran it in. Following that, superstar did the same mod to a seatpost. They also ditched it for the same reasons. Even one of the OG sample macneil posts that was sent to a distrubter was modified with this mod, it was ditched also! I am pretty sure thats enough reason right there why this seatpost mod is a very bad idea. You can do it to your post, it doesn't bother me, its your lose not mine.

[blkbike]

Trust me man, I work in the industry, if I ever suspected a warrantied frame had this seat post in it, the warranty would be completely voided. Its happened, I have personally seen frames fail due to this mod. Just because your frame may not noticeably be harmed, its doesn't mean that it doesn't happen.


This same mod was done on mountain bikes many years ago, they ditched it. It was too heavy and was damaging the frames that they ran it in. Following that, superstar did the same mod to a seatpost. They also ditched it for the same reasons. I am pretty sure thats enough reason right there why this seatpost mod is a very bad idea. You can do it to your post, it doesn't bother me, its your lose not mine.

not being malicious or anything but where is it that you work?

[Beanie]

considering the weight it adds, and the damage it can and will do to the frame outweighs the "coolnees" of not having a seatpost clamp :clap:

[Odysseus]

im 90% sure that the wedge would have to be horked on sooo hard to really flair out the seattube. seattubes are thin and wedges are strong. but the wedge is only tight enough to where as the seat doesnt move. plus he doenst use the seat at all. plus even if he did, hes only 120 pounds. there is no pressure on the wedge so therefor the frame cannot be damaged because if it didnt get damaged right away when he tightened it, then it wont magically be damaged when he doesnt use the seat. i understand that if it was near a weld it would weaken the weld. i am from a family of machinists and welders. i know how the detearioration of welds happens. but this wedge is in the middle of the seatpost where no pressure is applied uppon landing. the frame shall be fine. warranty is voided, but it was back in the day when he painted it. if the frame does break, which i doubt highly, it wont be at the seattube.

[jawn]

jawn-i have no idea what the hell your talking about

It's pretty simple, the wedge is 1", not 1 1/8" like you said.

[bmxmadness]

^^nope the wedge is 1 1/8"..

busades- i would like to know where you work..if you just work at bike shop your in no higher rank than i am pal. superstars mod was not quite like this one..they had a specific wedge taht was used only with the seat and the frame would still have to have a clamp..they used a wedge that was only able to tighten enough to keep the seat tight and was able to fit into a 25.4" seat tube..im not sure abuot the macneil mod or the mtb thing and i was into mtb before BMX and dont recall ever hearing about a pivotal seat for mtb. have you really seen this mod snap frames or are you jsut talking out your ass to prove a point..

me, odysseus and blkbike have basicly covered all the reasons why this seat mod is not as bad as you think...

[Busades]

I am not talking out of my ass! I have been around a lot longer than you have, and seen ideas come and go. I will no longer continue to go on about this mod since I have already said enough, I don't feel the need to argue over stupid mods when the people I fighting me have no clue. That being said yes it does look clean, and yes its a neat idea, but no I do not support such a mod due to the damaging effects that it can potentially cause to the majority of frames.

[bmxmadness]

Trust me man, I work in the industry, if I ever suspected a warrantied frame had this seat post in it, the warranty would be completely voided. Its happened, I have personally seen frames fail due to this mod. Just because your frame may not noticeably be harmed, its doesn't mean that it doesn't happen.


This same mod was done on mountain bikes many years ago, they ditched it. It was too heavy and was damaging the frames that they ran it in. Following that, superstar did the same mod to a seatpost. They also ditched it for the same reasons. Even one of the OG sample macneil posts that was sent to a distrubter was modified with this mod, it was ditched also! I am pretty sure thats enough reason right there why this seatpost mod is a very bad idea. You can do it to your post, it doesn't bother me, its your lose not mine.

Sorry to put you in your place young'in but there are still a lot of manufasctures useing that style of wedge in many very lght weight racing bikes and a few carbon bikes, like it stated the seat tube is the least needed tube in the bike, there are even bikes made with out i, I know you need to feel right but sorry your not I have been in the induustry longer than you have been tying your own shoes, keep riding and get better at that seems you need to learn about both have a great day,
Dad


^^that came from a my dad...a guy who has been in the bike industry for 21 years

[Busades]

like it stated the seat tube is the least needed tube in the bike, there are even bikes made with out i,

Your dad just lost all credibility right there.

[HaroStreet]

Just to let you kids know in advanced this post mod completely voids your frames warranty (regardless of weather you cut the frames seat tube), and is actually potently very harmful to your frame.


Just a quick rundown:

Case 1:
You run the wedge below the top tube, causing the seat tube to expand or ovalize. Weges are very powerful, they can easily ovalize 0.9mm tubing.

Case 2:
You run the wedge inside the toptube and seat stay junction area. Running the wedge here seems like a good idea, but in fact you are applying a huge amount of stress on the welds on this already highly stressed junction. There is a good chance that under load, you can crack the welds in this area. Having the seat this high also applies more stress to the frame since the seat tube does not penetrate low enough into the seat tube.

In both cases you are also canceling out the triangulation in your frame due to the location your are clamping your seat at. Basically your toptube junction has now become a fulcrum for your seat post, allowing your seat post to apply pressure within the main triangle of your frame.
racing bikes come like this and there tubbing is even thinner

[Busades]

racing bikes come like this and there tubbing is even thinner

You fail to realize the point, the application for that wedge in a fork sheer tube is very different from that in a seat tube. Its not that I am scared you may flair your seat tube, its the fact that you are bypassing the triangulation in your frame and putting a lot of stress on the upper junction. It does not necessary mean that your frame will brake, I am just pointing out that you are inherently creating the potential for that situation to be much more likely.

[HaroStreet]

You fail to realize the point, the application for that wedge in a fork sheer tube is very different from that in a seat tube. Its not that I am scared you may flair your seat tube, its the fact that you are bypassing the triangulation in your frame and putting a lot of stress on the upper junction. It does not necessary mean that your frame will brake, I am just pointing out that you are inherently creating the potential for that situation to be much more likely.
w/e i dont want to fight

[bmxmadness]

so my dad is old give the guy a break..and he is talking about the seat being like that..not just the fork...do some research...

[blkbike]

You fail to realize the point, the application for that wedge in a fork sheer tube is very different from that in a seat tube. Its not that I am scared you may flair your seat tube, its the fact that you are bypassing the triangulation in your frame and putting a lot of stress on the upper junction. It does not necessary mean that your frame will brake, I am just pointing out that you are inherently creating the potential for that situation to be much more likely.

its all good, thanks for clearing that up. if someone needs a translation he is saying that it does not necessarely mean the frame will break, only that it poses a small risk facter and that a normal setup would be "safer"

[jawn]

^^nope the wedge is 1 1/8"..

That's interesting, considering that wedge-style stems only existed for 1" threaded forks, and you mention using the wedge off an old stem... :>

[blkbike]

That's interesting, considering that wedge-style stems only existed for 1" threaded forks, and you mention using the wedge off an old stem... :>

that might be true but he works in a bike shop so he might have gotten ahold of one

[bmxmadness]

threaded quill style stems came in 1 inch and 1/18 inch..and i did you the wedge off of an old stem...im not going to lie about using a 1 1/8 inch wedge over a 1 inch one...that would be stupid

what else could a wedge like that be off of?...i cant think of anything but a stem...

[MrChikoStick]

pointless mod imo

[jawn]

They made 1 1/8" quill stems? I rode well before threadless came in, and I never saw one in BMX. In fact, the first threadless stuff for BMX was 1", simply because 1 1/8" head tube frames didn't exist. Perhaps it was a MTB thing? How does a 1 1/8" fork wedge fit in a 1" seat tube anyway?

P.S I never implied that you lied, I only thought that you were mistaken.

[blkbike]

I assume its from a road or mountain bike seeing as thats what the shop he works in specializes in.

[Odysseus]

yep im gonna assume its what he says it is. hes the one that took it off and then put it on. none of us can do anythign except say what we think, but bmxmadness knows the best out of any of us what it was. all i know is its working for him haha

[blkbike]

This thing is finally dying down lol. good im glad we can all act like immature kids again!

[dirkadirka]

i need a macneil set up now. ugh sigh

[jawn]

So, have we worked out where the 1 1/8" wedge came from then, so the readers can do this mod? Or is it just 1" after all, which case the readers can just get one of them?

[blkbike]

So, have we worked out where the 1 1/8" wedge came from then, so the readers can do this mod? Or is it just 1" after all, which case the readers can just get one of them?

We havent talked to bmxmadness, nor has he got online, so I think that is still up in the air

[bmxmadness]

ill bring it down from the air...i swear to you that the wedge is 1 1/8 inch..and it is off of an old mtb...im not sure how it fits but it does..if i can find a 1 inch wedge i will take a pic and you can be the judge of what mine is but thats the best i can do if you still dont believe me...

[jawn]

Yes, please do.

P.S So everyone with this mod gets the 1 1/8" wedge from an old MTB? I coulda sworn I read about some dude getting his from an old BMX quill stem (1"). Either way, I look forward to clearing this up. It must be confusing as hell for the readers.

[bmxmadness]

ok..i can do that..it may be a couple days..its been super busy at the shop so i havent had time to look for another wedge...most of the new cruiser bikes and 1 1/8 inch threaded quill stems...and im not sure on the bmx stem thing but your probably right about that

[fitbike61]

its funny how all this modification to the bike and work is all put in just to eliminated the look of a tiny piece of metal that is only a centimeter small. but u know those crazy bmxers that will do anything to their bike to make it different..