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Stem swap help

I'm looking to change my current stem to the TriRig Sigma and I need to see if it is doable with my current setup.

Currently running 100mm -6 stem and I want to change to the zero rise Sigma.

I have a 10mm spacer underneath the stem with a cable hanger that I will remove.
Ozero base bar with T4+ aerobars with 10mm pedestal spacer and I have another 5mm spacer set available. 

The math I was doing in my head seemed like I could get my same pad stack and reach by removing the spacer under the stem moving the pads forward on the bar 10mm and maybe adding the 5 mm spacer. 

Will this work or am I completely stupid? 


Nathan Kiser
Just FYI, you... are also less than mediocre. -TheActualPaulo

Comments

  • Options
    Doing what you propose will lower the stack a lot. If that is what your after it should work. I can check your math later but if you are aiming for same fit, you will need more spacers for sure.
    Zach Boring, Overly Average Looking Man
  • Options
    @zachboring nailed it. If you want the same exact fit, you'll need more spacers than what you are currently proposing. You'll be moving to a -17 stem, which effectively would lower stack approx. 10 mm worth *and* moves the bars further forward at...dammit, forgetting if its the sine or cosine of 73 degrees at that point. But it essentially creates more reach, meaning you'll need to move the bars backward to get the same reach, not forward.
    Resident Gear Guru
    Bike Crash Free Since August 4th, 2014
  • Options
    @nathankiser so hopefully I explained that ok on the Google call. If still confused by my crappy handwriting and inability to explain things coherently, play with this site.


    http://yojimg.net/bike/web_tools/stem.php

    If you plug in -6, 100 mm and 20 stack in #1 and the sigma stuff of 90 mm reach and 0 mm spaces, you see the difference of your proposed plan.

    With your plan you would be close to 40 mm lower on stack and almost spot on with reach.

    However, if you use 40 mm of spacer for the sigma input you are almost on with your stack, but your reach is short (you would move pads forward)

    Since you said you wanted to go lower (let's say 20 mm) you could experiment with this position using your current setup by taking out all the spacers and cable hangar. Using thsee inputs you would need 20 mm of spacers unser the sigma (20 mm) which is probably more aero and it would allow you to get lower later.

    Some notes: lowering front end, you will want to move the saddle forward and up to keep hip angles the same.

    Also, the sigma has a low clamp area, hence why experimenting before buying will be beneficial. Even if you put 40 mm of spacer under the stem, there would be some steerer left above the stem that would need to be cut to install the cover on the stem (or leave it off and put spacers above the stem until you are for sure) . The sigma clamping area is very short, thus why there would be steerer left above the stem.

    Again, hopefully this makes since, if not feel free to fire questios.
    Zach Boring, Overly Average Looking Man
  • Options
    thanks guys. I'll let you know how it turns out.
    Nathan Kiser
    Just FYI, you... are also less than mediocre. -TheActualPaulo
  • Options
    so does it matter where the spacers go?  below the stem or pedestal underneath the pads?
    Nathan Kiser
    Just FYI, you... are also less than mediocre. -TheActualPaulo
  • Options
    Below the stem would move the pads both vertically and horizontally back at either the sine or cosine of 73 degrees, whereas pedestal under the pads would move the pads in only the vertical plane.
    Resident Gear Guru
    Bike Crash Free Since August 4th, 2014
  • Options
    Alrighty.....my wife actually already bought me the sigma xf for Christmas.  Here's the idea after playing with that website, slammed stem, 30 mm pedestal risers which if I'm correct would give me 2mm less reach and would be 8mm lower. The reach is negligible right? and I can the ability to get lower I've just been working into it.  

    @zachboring, @rrheisler, Thoughts?


    Nathan Kiser
    Just FYI, you... are also less than mediocre. -TheActualPaulo
  • Options
    It will actually be about 18 mm short. Unless you meant add an additional 30 mm under the pads from what you currently have (10 mm)

    However, the thing to note is the baseball is going to be in a much different position than what you are used to. There is good and bad about thay, just be ready for it to feel pretty different.
    Zach Boring, Overly Average Looking Man
  • Options
    Ryan HeislerRyan Heisler Member
    edited December 2014
    ETA: Zach's got most of the math covered.

    As for the lower part, I'd be interested to know current saddle height and drop to aerobar pads as they exist. Would give an idea as to how much of a percentage that 8 mm would be and how easy that change will be.
    Resident Gear Guru
    Bike Crash Free Since August 4th, 2014
  • Options
    I went back and recalculate everything without pedestal risers and just the spacers under the stem. 

    Differences would be 5mm less reach and 29mm lower with the Sigma.

    Adding in the the pedestal spacer idea(10 mm on current setup and 30 in proposed setup) would make it 5mm less reach and 9mm lower? 

    But if I put a 10 under the Sigma, I should be 1mm higher and have 8mm less reach.  I could then move the pads and be essentially in the same position.

    My head hurts.....time to find the bourbon


    Nathan Kiser
    Just FYI, you... are also less than mediocre. -TheActualPaulo
  • Options
    I got the stem on. Ended up with zero rise, zero spacers under the stem and 15mm pedestal spacers. I've got to trim up the cabling to get them under the stem cover and I'll post some pics. It's pretty slick looking which is all that really matters, right?
    Nathan Kiser
    Just FYI, you... are also less than mediocre. -TheActualPaulo
  • Options
    Here's the before and after if you guys care.
    Before
    IMG_1048
    After
    IMG_1099
    TheoZach Boring
    Nathan Kiser
    Just FYI, you... are also less than mediocre. -TheActualPaulo

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