Results 1 to 22 of 22
  1. #1
    mtbr member
    Reputation:
    Join Date
    Feb 2016
    Posts
    290

    TMARS Dropper Cable replacement

    I have one of the newer TMARS with the "black box" cable entry.

    Two questions: History below...
    1/ Does anyone have a reliable technique or method for putting the black box back together ???
    2/ Where can I get a decent cable with the smaller cable end ???

    The cable is crap in every way (length (either too long or short), quality) and I have an internal front mech cable cable-outer I was hoping to use anyway... but I've got a 27.2 so choices are limited and I'm not ready to buy the Thomson $$$$

    First thing is the cable is normal gear cable diameter but pretty poor quality (as you might expect at the price point) ... but its also to long to go directly from the top tube and too short to take down via the BB

    I did get a gear cable in and then somehow got the bits back inside the black box (with a LOT of frustration and messing and when it did go in I'm not sure what I did differently to the preceeding 59 mins) but the seat wouldn't lock and it seemed the locking pin was actually fouling on the cable end... and I also messed up (kinked) the cable a bit getting the spring in ... (not totally but it wasn't ideal)

    So I pulled the lot out and took down the cable end on the grinder.
    Then spent another hour trying to get the damned mechanism back in the black box... I tried pulling .. but that pulls out the back so the pin won't go into the hole as its at an angle .. then pushing with a screwdriver ... and somehow it did go back in...

    At some point I'd planned to customise the old front mech shifter and then put it back on the iSPEC so I'm going to need to do all this again.... it's more or less working now... but I used a cable slightly too short and the result is its a bit stiff but works!

    Therre must be a technique to getting these things back together but I'm missing it!

  2. #2
    mtbr member
    Reputation: tk1971's Avatar
    Join Date
    Aug 2007
    Posts
    478
    Have you looked here for tips:

    REVIEW: TMARS Dropper Post

    https://www.youtube.com/watch?v=pdWLQ6lPakA

    The video looks like what you need.

    Good luck.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Feb 2016
    Posts
    290
    Thanks tk,
    The video shows how to disassemble including the black box then fits a new cable and black box. The bit I'm missing if anyone knows is getting the black box back together once the cable is in against the spring without the diamond shaped slider coming out ... Or do you reinert without the slider and then insert it? Or do you reinsert and then get the cable through?

    Messing about with the cable already in the spring and the diamond shaped slider in and trying to insert it just messes up the cable

  4. #4
    Armature speller
    Reputation:
    Join Date
    Sep 2004
    Posts
    1,861
    I've always ground the cable head down to the right size before trying to insert it and have never disassembled the mech.

    Black box assembled and then thread cable through.

  5. #5
    mtbr member
    Reputation:
    Join Date
    Feb 2016
    Posts
    290
    Ah, thanks Nordieboy.
    I hadn't tried much since the cable I was trying to replace it with was just starting to fray and didn't go in easily (taken off a barely used rear shifter) and I didn't want to make it any worse.

    I'm wondering is it the same size as a Campagnolo gear cable end or is it smaller again?

  6. #6
    mtbr member
    Reputation: tk1971's Avatar
    Join Date
    Aug 2007
    Posts
    478
    Most new shift cables come with two ends. One smaller than the other. Is the size you need smaller than the smallest one?

  7. #7
    ***** lurker
    Reputation: cfanto's Avatar
    Join Date
    Oct 2010
    Posts
    111
    Quote Originally Posted by tk1971 View Post
    Most new shift cables come with two ends. One smaller than the other. Is the size you need smaller than the smallest one?
    The T-Mars' OEM cable head is a lot smaller than a typical shift-cable's head (even the smallest one). When I frayed the hell out of my old one & couldn't feed it back thru, I went online to look for a replacement cable & realized they were nowhere to be had. So I just grabbed a spare shift-cable & grinded the cable head till it fit. I had to further sand it smooth as the head was kinda binding against some of the moving parts in the TMars. Greased it all & closed it up... it's been more than a year now & so far, so good.

    2017 Specialized Turbo Levo
    2016 Motobecane Lurch
    2015 Motobecane Sturgis Bullet

    2012 Canfield Jedi
    2011 Giant Reign
    2011 Raleigh Renevio


  8. #8
    mtbr member
    Reputation: tk1971's Avatar
    Join Date
    Aug 2007
    Posts
    478
    What about Brompton / Sturmy Archer shift cables?

    The following info swiped from:

    https://fernandoj.wordpress.com/tag/...on-gear-cable/



    From top to bottom: conventional stainless steel gear cable (Jagwire), Campagnolo and small headed Brompton cable (itís red!)

  9. #9
    ***** lurker
    Reputation: cfanto's Avatar
    Join Date
    Oct 2010
    Posts
    111
    The Brompton looks promising...

    2017 Specialized Turbo Levo
    2016 Motobecane Lurch
    2015 Motobecane Sturgis Bullet

    2012 Canfield Jedi
    2011 Giant Reign
    2011 Raleigh Renevio


  10. #10
    mtbr member
    Reputation:
    Join Date
    Feb 2016
    Posts
    290
    Quote Originally Posted by cfanto View Post
    The Brompton looks promising...
    Yep, that looks about right.

    Life cfanto I ground down a bigger one. (Shimano/SRRAM sized)

    This is pretty simple....
    The problem was initially threading the cable back through.

    (Its a pain for me taking out the seatpost.... my bike has an internal seatpost clamp... which is a lot more hassle than it sounds... the angle makes it easy to get the hex wrench at the wrong angle and you cant make a full turn or the frame is in the way... so the bolt head gets damaged easily, especially when you are on a trail - I'm already using a replacement bolt and that's already damaged so I don't like keep messing with it as the last thing I want is to round it off and not be able to get it out)


    I understand (read) there are also some variations in cable diameter (1.1 vs 1.2mm). I don't own a micrometer but there is definitely a difference between a Goodridge cable and Shimano I have. (The Goodridge is thinner)

    The reason I've not bought the dual ended type for ages is two fold:

    1) They seem to be the budget lines and these seem to then have no specific nominal width ... in other words manufacturing tolerance ...

    2) My bike is internally routed cables - changing the lot is a pain compared to changing the inner and when you cut the cable it already starts to fray so I don't want to scratch up the insides of the outers

    3) (Yep I said 2 but) - When you actually compare they difference is huge. I had a issue with the kids bike shifting and I swapped everything out except the cable (same shifters and mech as my bike and a pretty new cable) ... the cable by itself with no load felt fine ... but when I did change the cable and outer for a expensive one everything worked "like new".

    Anyway, I realise this is a budget dropper so it would be better to not spend half as much on a cable as the dropper itself...

    @cfanto ... Did you rewire the blackbox without taking it apart....?
    I wonder if the smaller cable diameter might be easier....

  11. #11
    ***** lurker
    Reputation: cfanto's Avatar
    Join Date
    Oct 2010
    Posts
    111
    Quote Originally Posted by Steve-XtC View Post
    @cfanto ... Did you rewire the blackbox without taking it apart....? I wonder if the smaller cable diameter might be easier....
    I actually took the blackbox apart before recabling just so I could regrease it all up. I don't seem to recall having any issues regarding feeding the cable thru but I would believe that a smaller diameter cable would be easier to work with as well as create less friction inside the cable housing during use.

    2017 Specialized Turbo Levo
    2016 Motobecane Lurch
    2015 Motobecane Sturgis Bullet

    2012 Canfield Jedi
    2011 Giant Reign
    2011 Raleigh Renevio


  12. #12
    mtbr member
    Reputation:
    Join Date
    Feb 2016
    Posts
    290
    Quote Originally Posted by cfanto View Post
    I actually took the blackbox apart before recabling just so I could regrease it all up. I don't seem to recall having any issues regarding feeding the cable thru but I would believe that a smaller diameter cable would be easier to work with as well as create less friction inside the cable housing during use.
    Sorry, I should have been more specific in the question....
    Did you take all the bits out of the blackbox (spring, sliding bit and the lozenge shaped bit with the pin)

    I think the difficulty I had was getting the whole lot back inside when I'd already put the cable through.... and I should have put it all back then the cable ???

    Since the present solution is "temporary" (in that I mean to make a lever from an old front mech) but its actually all back together and working I'm a bit loathe to pull it apart and check if I can get it easily back together ... (last time must have taken an hour of swearing and frustration)

  13. #13
    ***** lurker
    Reputation: cfanto's Avatar
    Join Date
    Oct 2010
    Posts
    111
    Yes, I did take the blackbox completely apart when regreased it. The first time, I did fumble around trying to figure out how it all went back together. The second time, I kinda already knew how all the pieces worked together so it wasn't difficult to reassemble. It's been a while since I've taken her apart, but the cable was definitely the last thing to install. In fact, you shouldn't need to disassemble the blackbox to remove/install the cable.

    In regards to the OEM lever, it was crap - just didn't quite fit well in the cockpit esp. if you have a front shifter. So when they came out with their revised version, I ordered it - still looks cheap & unrefined but has better leverage and meshes much better with all the other components on the bar.

    I also converted an old front shifter to a dropper lever for one of my other (non-T-Mars) dropper posts, but I didn't know how I could use it for the T-Mars since the barrel of the cable is on the other side at the post & not at the lever. I tried looking for knarps but most (at least the ones I could find) are too large to fit inside a front mech. Let me know if you found a way to use a front mech w/ the T-Mars.

    2017 Specialized Turbo Levo
    2016 Motobecane Lurch
    2015 Motobecane Sturgis Bullet

    2012 Canfield Jedi
    2011 Giant Reign
    2011 Raleigh Renevio


  14. #14
    Armature speller
    Reputation:
    Join Date
    Sep 2004
    Posts
    1,861
    Quote Originally Posted by cfanto View Post
    I also converted an old front shifter to a dropper lever for one of my other (non-T-Mars) dropper posts, but I didn't know how I could use it for the T-Mars since the barrel of the cable is on the other side at the post & not at the lever. I tried looking for knarps but most (at least the ones I could find) are too large to fit inside a front mech. Let me know if you found a way to use a front mech w/ the T-Mars.
    2 cables with a cable joiner. Just can't use a 1 piece outer though.

  15. #15
    mtbr member
    Reputation:
    Join Date
    Feb 2016
    Posts
    290
    Quote Originally Posted by NordieBoy View Post
    2 cables with a cable joiner. Just can't use a 1 piece outer though.
    Those were my thoughts partly as I already have an internal cable path for the now removed front mech but also thought I might be able to add an inline tension adjuster on the uptube whilst doing it ?

    Problem with both seems to be that most go back to the same issue in being designed to extend a cable with only one 'free' end


    Sent from my iPhone using Tapatalk

  16. #16
    mtbr member
    Reputation: watts888's Avatar
    Join Date
    Oct 2012
    Posts
    5,633
    There seems to be two different versions of the switch and cable housing inlet at the post. Any opinions on the black box vs. the straight out version? How about the lever? Problems with the multi-direction one? Does one wire up horribly?
    https://www.amazon.com/dp/B00XYDPZL4...CSY8DKBANST79T
    https://www.amazon.com/Tmars-Adjusta...8434793&sr=8-2
    "a hundred travel books isn't worth one real trip"

  17. #17
    ***** lurker
    Reputation: cfanto's Avatar
    Join Date
    Oct 2010
    Posts
    111
    Quote Originally Posted by watts888 View Post
    There seems to be two different versions of the switch and cable housing inlet at the post. Any opinions on the black box vs. the straight out version? How about the lever? Problems with the multi-direction one? Does one wire up horribly?
    https://www.amazon.com/dp/B00XYDPZL4...CSY8DKBANST79T
    https://www.amazon.com/Tmars-Adjusta...8434793&sr=8-2
    I hated the original multi-directional lever. I eventually bought the updated version replacement lever kit (first link). Slightly better ergonomics & meshed better with the brake & shift levers. Also, the multi-directional one is more 'messy' to work with - I usually end up with frayed ends - good luck if you need to remove & reinstall the lever.

    2017 Specialized Turbo Levo
    2016 Motobecane Lurch
    2015 Motobecane Sturgis Bullet

    2012 Canfield Jedi
    2011 Giant Reign
    2011 Raleigh Renevio


  18. #18
    mtbr member
    Reputation: watts888's Avatar
    Join Date
    Oct 2012
    Posts
    5,633
    More differences. Looking at the vendor's catalogue, the one with the red accents and multi-direction lever use a chromoly steel center post. The one with the black box uses an aluminum AL6066 for the center post. It looks like the outer post is AL6066 for both. Since it uses a metal rod to control the height, can't help but wonder if the steel center rod is better for strength. I could see the aluminum one getting ovalized or scratched up in time.

    For reference, I'm in the solid clyde territory, and material strength makes a huge difference to me. Weight, not so much.
    "a hundred travel books isn't worth one real trip"

  19. #19
    Armature speller
    Reputation:
    Join Date
    Sep 2004
    Posts
    1,861
    Mine has the multi-directional lever and the pin box on the seatpost is at the back and points straight down.

  20. #20
    mtbr member
    Reputation: watts888's Avatar
    Join Date
    Oct 2012
    Posts
    5,633
    Quote Originally Posted by NordieBoy View Post
    Mine has the multi-directional lever and the pin box on the seatpost is at the back and points straight down.
    Is this one of the recent versions, or older? I still need to check if I can even fit the 445mm version in my frame. Based on amazon's images, it needs about 110mm of seatpost sticking out with a regular seatpost, and I'm not sure I have that right now. It might be close.
    "a hundred travel books isn't worth one real trip"

  21. #21
    mtbr member
    Reputation: watts888's Avatar
    Join Date
    Oct 2012
    Posts
    5,633
    So I bought the newer t-mars, and I think I'm a dropper convert. It definitely helped on a lot of the technical sections and getting a little lower on the corners.

    However, at 240 lbs and one ride, I can't help but think those plastic bushings are going to fail quick. New out the box, zero play. it rotates some and has a little wobble going on now, after a single 2hr ride. Any aftermarket aluminum spacers and bushings, or did you just replace with the same plastic ones over and over? Concerned about the bushings and the top ring too. I think it's where I'm getting a lot of wobble.
    "a hundred travel books isn't worth one real trip"

  22. #22
    mtbr member
    Reputation: watts888's Avatar
    Join Date
    Oct 2012
    Posts
    5,633
    Just in case anybody comes across this link in the future, replacment bushings are available from Tmars.
    https://smile.amazon.com/Tmars-Repai.../dp/B01M0R054C
    https://smile.amazon.com/Tmars-Drop-.../dp/B014F8JMSS
    "a hundred travel books isn't worth one real trip"

Similar Threads

  1. Who uses a Tmars dropper?
    By traditiionalist in forum Components
    Replies: 11
    Last Post: 08-01-2016, 10:59 AM
  2. Budget dropper: KS eTen vs. TMARS/Gravity8 vs...?
    By MarcusBrody in forum Components
    Replies: 23
    Last Post: 07-10-2016, 01:27 PM
  3. TMARS 419s dropper won't lock in
    By SlowerThanYou in forum Components
    Replies: 3
    Last Post: 04-08-2016, 08:14 PM
  4. Best Way to Secure Dropper Cable?
    By magnato1 in forum 29er Components
    Replies: 10
    Last Post: 05-27-2015, 12:29 AM
  5. Broken dropper cable
    By Bigb2000 in forum Specialized
    Replies: 2
    Last Post: 11-15-2013, 05:14 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •