internal dropper-post routing

[sprout]

would anybody like to talk about internal routing for dropper posts?

i'm having a bit of a conundrum regarding down tube to seat tube routing for a thomson 'covert' dropper.
not totally fluent in internal routing, though i've given it a go.
i am confident that i can make the bend -- from the down tube to seat tube -- without significant increase in housing friction.
all of the 'extra' has been carved out of the bb shell as well as the dt/st junction.
how/where do i secure the guide tube inside of the seat tube?!?
current thought is to bend the guide tube, braze into the dt, test fit, then drill a hole in the back of the seat tube where the internal tube will contact and braze in through there.
i imagine some of you have done this in a more slick fashion.
yeah, you can weigh in on brass vs stainless but there's another strand for that. i'm using 5/16 .o32 brass.

thoughts?

best,
--edwin brown


i'm not good at internets. be nice. #firstpost

[Jake Rosenfeld]

Yo Edwin!

In my pea brained imagining of the condition inside the seat tube the routing tube would stop just a couple inches above the bb inside the seat tube and need no fastening.
It would exist in a vertical position and be too short to rattle.
The attachment at the other side of the bb in the dt would be plenty.
If you were worried about sharp edges you could braze a nipple of 3/8 rack tubing over the st end and deburr the edges so there was nothing to catch the housing as it slides thru.

Just shooting in the dark here, never done a dropper. Sounds clean though!

Later,
Jake

[zank]

I'm doing a Thomson Covert build for myself as well. I am throwing around two different attack plans. I'd like to machine a nice entry into the head tube and then into the DT and through the BB into the ST. I am also thinking the more traditional route of going external along the down tube and then into the seat tube through a hole in the seat tube. Either way though, the Covert does not require any guide tubes. It's fine for the housing to be free inside the tube and the housing meets up directly to the bottom of the post. Piece o' cake. If you are worried about the housing rattling around, you could come up with some creative solutions wrapping the housing in some foam or something like that.

Keep us posted on how it goes for you. Have fun!

[steve garro]

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I am also thinking the more traditional route of going external along the down tube and then into the seat tube through a hole in the seat tube.

Other then…….not sure why other then look……..why?

Not arguing, just want everyone's dos centavos.

With triple stops & no FD mech there's an empty hole…...
- Garro.

[zank]

Yeah man, that is super clean (love that color too!). Looks killer and is super functional. I just kinda dig the idea of having that cable run internally. Just being vane I guess :)

[steve garro]

IMG_6845.JPG

Yeah man, that is super clean (love that color too!). Looks killer and is super functional. I just kinda dig the idea of having that cable run internally. Just being vane I guess :)

That's all good.

The one thing is that the bottom curve is one hell of a gunk collector internally.
Not an issue in the short term, I'd just really try to think out the issue of sealing internally.

It has to be a full run of housing so you can raise & lower the seat to take it out, yeah?

One thing on the dropper posts is that extra vigilance will have to be taken against the SP seizing, there is ALLOT of post in the frames, and as they will not be removed often then you can see where that goes……why take it out……..just lower it & toss it in the trunk………imagine removing a seized dropper - much crying & gnashing of teeth.

Thanks on the scoot, here is a sun pic.
Dropper works ace, FYI - the Mrs has the same set up.
- Garro.

[VertigoCycles]

yo Steve, that's a sweet looking ride for sure.

On smaller bikes than that one, with the Thomson, the housing drops down and can interfere with the tire. I tend to build bikes with the post very nearly maxed out and the external routing can be a challenge to manage.

Edwin,

On the internal droppers I've done thus far, I've just routed them down the DT and into the side of the ST. I like the idea of the insertion being at the head tube and thought that milling a slot on top of the BB, essentially connecting the vent holes for the DT and ST, and then mitering both the ST and the DT at the overlap would probably give the smoothest housing run. I can't seem to get past the lack of a full weld on the BB though. I bet you could wrap some heavy duty zip ties around the housing and pull it back into the frame to help quiet the rattle...sort of like the Di2 internal method.

[steve garro]

That's some great beta!

- Garro.

[zank]

I think you guys have talked me into the external on the down tube option.

[steve garro]

I think you guys have talked me into the external on the down tube option.

Looking forward to your take on it.

- Garro.

[Will Neide]

I think you guys have talked me into the external on the down tube option.

Stupid question....are you going external on the downtube and then into the seat tube at the bottom for an internal routed post?

I came from a gravity dropper which I ran down the downtube and up the back side of the seat tube. I tried to do the same thing with my Thomson 27.2 externally routed post and due to the fact the cable attaches at the head I ran into issues with the cable either binding or looping near the bottom bracket when I lowered the saddle. I ended up switching to top tube routing only for externally routed Thomson droppers.

[zank]

Yes, that's the way I'm leaning now. I am still going to see if I can form a nice housing loop in the BB shell if I come out of the DT breather into the BB, under the BB plastic sheath, and take the long way around back into the ST breather. If it looks OK, I'd still like to go fully internal. We'll see, but I'll let you guys know either way.

[fortyfour]

@Zank:

I considered routing in the DT and then looping through that overlap and into the ST so basically hiding the whole thing. The only problem though is threading that needle and if should ever have to do any service on that sucker it's a royal PITA to thread that thing back and forth in addition to having to deal with grease on the post and inside the seat tube. What a mess...

What I ended up doing was doing a stealth routed dropper inside the seat tube, exit point low on the non-drive side of the seat tube and then run it up the non-drive side along the down tube. The client had me order a right handed version but runs it upside down on the left hand side of the bars to keep it kind of tucked down and out of the way. I found it much easier to actuate it that way too.

Controls:



Routing:



I would fashion a cover plate in hind sight for that slotted opening to help keep out gunk. The slot I felt worked out well though for passing the cable down and through. It was a bit of a juggling act however getting that stuff all run through and greased up..

From the side view, I placed the guides just off center so to hide the cable from view. Turned out ok I think:



I have a similar build coming up that I will do it like this and another very soon which will use PMW's triple stops along the underside of the TT as the client wants to swap between dropper and rigid post depending on racing/conditions/terrain.

[False Flats]

I'm just putting together a new mtb for myself that takes a similar approach as Kris has shown above, but I decided to go with internal routing for the down tube as well. I'm using a Reverb Stealth with a RH lever I flip upside down and run on the left side of the handlebar.

For the DT, I'm running 7mm brass tube. In the seat tube, I'm using a small length of the same brass tube that sits about 4cm below the max insertion point of the post.


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Cheers.

[Albert S]

Hey Guys, figured I might share my solution too...

We're using a standard diamond shaped reinforcing boss but drilling it out to 8mm (they're 6mm std) - works nicely with the Jagwire rubber grommets below to provide a nice tight seal. Running external along the DT sharing FD routing for the new Shimano side-swing. The Jagwire drawing is a bit misleading as it's a lazy cut-n-paste Di2 grommet drawing but I can assure it's a straight through 5mm port and angled for a nice cable run (i.e. not 90deg entry)

WATER BOTTLE BOSS REINFORCEMENT PLATE STAR SHAPE :: REINFORCEMENTS :: H2O BOSSES :: STEEL SMALL PARTS :: BRAZON/SMALL PARTS :: Nova Cycles Supply Inc.

Blanking grommet (#CCN009):
CCN009.jpg

W/ routing grommet (#CCN007NB-2):
CCN007NB-2.jpg

Royal PITA in terms of placement if you're factoring-in an FD. You sorta have to pledge allegiance to either T/S or D/S (or side-swing).

[zank]

@Zank:

I considered routing in the DT and then looping through that overlap and into the ST so basically hiding the whole thing. The only problem though is threading that needle and if should ever have to do any service on that sucker it's a royal PITA to thread that thing back and forth in addition to having to deal with grease on the post and inside the seat tube. What a mess...

Sold. Thanks for sharing, everyone! Awesome stuff all around.

Albert, do you have a source for those CCN009 grommets?

[steve garro]

How about good old "noodles?"

Exit the TT/SS/ST crotch with a noodle, shortening up the housing run so it won't rub the tire?

Just thinking out loud…….

- Garro.

[fortyfour]

@Albert: I'd be curious about a source for the CCN007NB-2 but have them the size of the brake cable (The only one's I've seen are specific to Di2).

@Zank: You can get a variety of sizes/dimensions for common Mil. Spec. Push In Grommets via McMaster and others. Here's the link to all the push-in grommets via McMaster.

Actually, something like this (which happens to be a Nuke Proof Part) would be ideal.

[zank]

Very nice. Thank you, sir!

[Albert S]

I'm sourcing direct from Jagwire Taiwan (little help to most of you, I know). They're a stock item in the OEM catalogue so I see little reason why Jagwire USA couldn't get hold of/offer them. Maybe give them a shout?...(info@jagwire.com)