MTB: downtube cable routing

David Bonnell said:

One of the MTB frames that I'm considering uses downtube cable
routing.

This seems a bit odd, given the amount of grit/grime/moisture that
frequents the downtube/bottom bracket. Does anyone have positive/
negative experience to share on the subject? My road bike has
downtube cabling, but I don't smash it over rocks or take it through
mud pits.

I've seen it done on some full-suspension frames, and it seems to work
well at least in dryish conditions. I'm not sure about serious amounts
of mud though. Does the frame use housing to run the cables under the
BB, or a road bike style cable guide?

As for rocks, I wouldn't be too worried. Your odds of bashing the
underside of the BB shell on a rock without destroying your chainrings
in the process are not terribly high.

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Quoted message said:

My full susser has that setup. I rode that bike through this past New

England winter, and it saw plenty of snow, muck & grime. Even after
hours of snow, including trudging through over the BB, the rear brakes
actuated. They didn't necessarily grab as I'd like, what with
everything covered in slush and/or frozen, but they actuated. I'll
have to check the rear brake cable though, that one may come down the
top tube. I'll try to remember to look tonight. It's a Marin, if you
want to check sooner.

My (potentilal) bicycles don't have problems with slush or snow...my
body shuts down long before my bicycle in those situations. I'm not
looking at FS...specifically looking for a XC hardtail.

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Mud has been a non-issue in regards to functionality, but I don't ride
in very muddy conditions, be nice to the trails and all that. It
definitely requires more attention than cables with a cleaner route.

I prefer riding in the dry, but it's pretty tough to avoid mud/
moisture on the trails here. I just don't see the positive in this
cable routing choice (for an XC hardtail, that is)...in other words,
why would a manufacturer decide to do this?

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Where are the bottle cages on this frame? Mine has one on the bottom
of the down tube with the cables (yuck!) and the other is on top of
the top tube, where it's crushed in any emergency dismount or crash.

Ugh...fortunately, this will be a large frame, and bottle cages will
be in standard positions on the seattube and downtube. Under the
downtube? Geez, that's nasty.

Thanks for the input.

David Bonnell said:

One of the MTB frames that I'm considering uses downtube cable
routing.

This seems a bit odd, given the amount of grit/grime/moisture that
frequents the downtube/bottom bracket. Does anyone have positive/
negative experience to share on the subject? My road bike has
downtube cabling, but I don't smash it over rocks or take it through
mud pits.

It does make a difference, but not that much. Put some oil on your cables
where they pass under the bottom bracket before every dirty ride, and they
should stay moving OK.

Matt O.