Another Front Derailleur Question

[Sbloomer]

Hi all

 

I have another question around front derailleurs.

 

My builds frame is a top pull front derailleur,  But what confuses me is that the cable slot (whatever it is called - see picture) is angled slightly to the side of the frame away from the drivetrain, instead of directly downwards.  This means that the cable down to the front derailleur is not straight.  I would have thought this is suboptimal.  Or do I have the wrong derailleur?  I have an X0 Top-pull low mount that I bought from a hubber, but everything seems very stiff.

 

 

 

[MORNE]

most probably has to do with optimising this:

 

 

https://www.sheldonbrown.com/cables.html

 

same with the rear derailleur..there is an optimal length of cable/radius/ entry angle to minimise the amount the cable binds where it leaves the housing.

[dewaldsss]

This should do it

 

https://www.parktool.com/blog/repair-help/cutting-and-sizing-cable-housing

 

https://www.parktool.com/blog/repair-help/front-derailleur-advanced-troubleshooting

 

https://www.parktool.com/blog/repair-help/how-a-front-derailleur-works

 

https://www.parktool.com/blog/repair-help/front-derailleur-adjustment

[David Marshall]

Can you not route the housing on the far side of the frame?

[Headshot]

Another question: What is a front derailleur?

[ChrisF]

From this rebuild - https://community.bikehub.co.za/topic/181779-mongoose-rebuild-project/page-1

 

 

 

The cable is angled away from the tube, and also slightly sideways (not clear in this pic)

 

 

 

This is just how they built the bikes back then .....

 

 

Best solution is to re-cable it as follows ...

 

[madmarc]

From the OP pic, the cable is routed on the wrong side of the frame, it must sit on the non-drive side, this will line it up with the angle of the frame lug and intern line up at the correct angle where it connects to the FD. The way its mounted now will case a sharp angle at the seat tube lug resulting in hard pull to change

 

No need to make the extra loop like referred to for RD this is not required for FD as the cable outer does not move when changing like it does with RD. Only make sure the outer is cut to a length to accommodate a smooth corner transition from the top tube luge to the seat tube lug.

 

MorneS555 pics refer to a brake cable on MTB or road rim brakes, here there needs to be a bit of a loop as the cable also move when pulling brakes. Not relevent for FD cables

[Sbloomer]

From the OP pic, the cable is routed on the wrong side of the frame, it must sit on the non-drive side, this will line it up with the angle of the frame lug and intern line up at the correct angle where it connects to the FD. The way its mounted now will case a sharp angle at the seat tube lug resulting in hard pull to change

 

No need to make the extra loop like referred to for RD this is not required for FD as the cable outer does not move when changing like it does with RD. Only make sure the outer is cut to a length to accommodate a smooth corner transition from the top tube luge to the seat tube lug.

 

MorneS555 pics refer to a brake cable on MTB or road rim brakes, here there needs to be a bit of a loop as the cable also move when pulling brakes. Not relevent for FD cables

 

 

BOTH front and rear are routed under the top post on the drive side of the frame.  To loop it on the other side would make force the cable to be routed around the seatpost.  But my question is not really about the routing of the cable.  The lug itself is pointing the wrong way in my mind.  I noticed the same on my Trance, which I bought after a conversion. 

 

To change to a 1x will mean changing all my stuff, including crankset.  I can't afford to go that route as it was supposed to be a budget build.

[ChrisF]

I was helping a friend service a couple of bikes yesterday.  Two of the bikes were older, and also had some STRANGE cable routes !!

 

The one bike did have issues with shifting, so I unclipped the outer cable and loosened the full length.  Then cleaned the cable.  That outer cable had already set with its awkward multi-bends, and you could feel the friction to move it !!  Cleaned it with Shimano spray, and re-assembled.  The improvement in shifting was immediate and drastic.  YES, I know it will soon get dirty and sticky again ...

 

 

Sadly the older frame layouts were "less than ideal" ....

[madmarc]

BOTH front and rear are routed under the top post on the drive side of the frame.  To loop it on the other side would make force the cable to be routed around the seatpost.  But my question is not really about the routing of the cable.  The lug itself is pointing the wrong way in my mind.  I noticed the same on my Trance, which I bought after a conversion. 

 

To change to a 1x will mean changing all my stuff, including crankset.  I can't afford to go that route as it was supposed to be a budget build.

 

that's what i'm trying to explain, the lug is angled towards the non-drive side of the frame so the cable enters from the non-drive side.

 

[Sbloomer]

We’re not getting each other.

 

This is the lug in question. Taken from the non drive side.

 

 

I’ve just examined my daughter’s silverback (which I got from the hub yesterday). It has the same configuration.

 

 

Conclusion. I have the wrong front derailleur.

[Sbloomer]

Scouring the web it looks like I need one of these. 

[madmarc]

Ahah yep we not on the same page, i read your post as the lug being angled the opposite way.

 

My apologies i stand corrected

[Sbloomer]

So it seems the only compatible mechanisms are the Shimano M785 and the M675-B

 

Now to flog all the wrong stuff again

[ChrisF]

So it seems the only compatible mechanisms are the Shimano M785 and the M675-B

 

Now to flog all the wrong stuff again

 

This ???

 

[Sbloomer]

This ???

 

Indeed