Front mech cable routing

[Pale Rider]

I've noticed the front mech cable on some bikes is routed under the bottom bracket, and on others it runs down the seat tube.

Presumably, both routings allow the front mech to do the desired job - shift the chain - so it doesn't really matter.

But I'm curious as to the reasoning behind routing the cable one way or the other.

 

[Milkfloat]

I've noticed the front mech cable on some bikes is routed under the bottom bracket, and on others it runs down the seat tube.

Presumably, both routings allow the front mech to do the desired job - shift the chain - so it doesn't really matter.

But I'm curious as to the reasoning behind routing the cable one way or the other.

On and MTB and presumably a cross bike - a top pull is used to try and keep the crud that hits underneath the bottom bracket away from the cables. I would assume that road bikes are following this trend as they are not totally immune to crud either.

 

[Pale Rider]

On and MTB and presumably a cross bike - a top pull is used to try and keep the crud that hits underneath the bottom bracket away from the cables. I would assume that road bikes are following this trend as they are not totally immune to crud either.

My Cannondale MTB has the cable routed under the bottom bracket, as is the cable for the rear mech.

I did wonder about crud, although I rarely venture off the cycle path.

Could be a problem for proper mountain bikers.

 

[KneesUp]

My bike (from 1990 - originally a mountain bike) also routes the cables under the bottom bracket. I expect along the top tube and down the seat tube would keep it cleaner, but it works.

I've converted the frame into an everyday/touring type bike though, and having both gear cables on the underside of the downtube does mean that I can't easily get a third bottle cage on the downtube, even though there is plenty of room, because the mount would foul the cables.

 

[winjim]

My bike (from 1990 - originally a mountain bike) also routes the cables under the bottom bracket. I expect along the top tube and down the seat tube would keep it cleaner, but it works.

I've converted the frame into an everyday/touring type bike though, and having both gear cables on the underside of the downtube does mean that I can't easily get a third bottle cage on the downtube, even though there is plenty of room, because the mount would foul the cables.

I had that problem when mounting a crudcatcher. I found that the locknuts from presta valves made ideal spacers and gave me just enough clearance for the cables.

 

[mjr]

On and MTB and presumably a cross bike - a top pull is used to try and keep the crud that hits underneath the bottom bracket away from the cables. I would assume that road bikes are following this trend as they are not totally immune to crud either.

I think my 1980s road bike has cable rings and an outer routing it past the top of the bottom bracket and then up into the front mech... so there's a third option.

 

[mythste]

On and MTB and presumably a cross bike - a top pull is used to try and keep the crud that hits underneath the bottom bracket away from the cables. I would assume that road bikes are following this trend as they are not totally immune to crud either.

Quite the opposite for cross bikes, down tube so you can shoulder the bike without having cables digging in.