SamJ

I am trying to design my first frame and I am curious about the decision criteria for locating cable stop braze ons.

I have seen them on top of the top tube, on bottom of the top tube and on bottom of the down tube. Is this purely asthetics or are there some design considerations to the location of the cable stops?

For reference I am designing a bike for touring and my preference would be to run all the cables down the bottom of the down tube so that I can strap a bag to the top of the top tube and use the bottom of the top tube to mount tent poles or possibly an extra water bottle.

I would appreciate any help with understanding the decision criteria for locating the cable stops.


Thanks in advance

unterhausen

as long as you can get a smooth cable run, it's personal preference. But there is nothing more exciting than the thought that the cable is going to hit a tube -- after the bike has gone to paint

lverhagen

I think in your circumstance, I would locate the stops on the side of the top tube as on some older mountain bikes and some cross bikes. This allows your tent pole/water bottle idea. The biggest problem with the bottom of the downtube is the difficulty in routing the cable to the rear brake unless you plan on using disks, drums, or a chainstay mount u-brake. Cablestops on the toptube allow most "normal" brake setups for touring - cantis, v-brakes, longreach calipers, etc.

Cheers

unterhausen

unless you are making your first frame at a class, I'm not sure I would go for a touring bike.

If you are getting someone else to make it, you might consider running the brake cable through the top tube

Chop61

Why wouldn't make your first bike a touring bike? Just curious.

unterhausen

go browse crazy guy on a bike for a few hours and see how many reports of broken frames there are on there. The static and dynamic loads on a touring bike are considerable.

pyeyo

I am onboard with Iverhagen, the side of the toptube is the place. I doubt you would be using a u-brake setup but the disc isn't really too bad an idea. Is this going to be a fully loaded touring bike or just more relaxed geometry?
The only time I vary the stops is if I'm installing travel couplings which require a little more thought at the transition point. Occasionally I'll braze cable guides to the head tube to keep the housing lined up to the shift cable adjusters and act as anti rub guides.
Post some photos as you go along.

SamJ

Thanks for the all the comments and sorry for my slow response (how do I set up my account so that I receive an email when someone replies to my posts?)


1. The bike will be for fully loaded touring.
2. I will not be fabricating the bike, I just want to do the design.
3. I am pretty sure I am going to use disc brakes. Any reason not to? Design considerations for disc brakes?

A follow up question:
What are the PROs and CONs of routing the cables inside the tube and how would I spec this on a drawing? Anyone have some pics of what this internal routing looks like (the entry and exit points)? I like the idea of internal routing, seems like that would keep the look of the bike very clean but I would be concerned with maintenance issues.

Thanks for the help

unterhausen

pros of internal brake cable routing are mostly that people like it; I think yours is the first case where there is any practical advantage. Cons are it is more work, so I'm sure there will be a charge for it. Some builders really hate doing it. It has never really been my style, but I'm about to do my first internal routing. Typically, the cable goes in at the rider's 7 o'clock and comes out at about 11 o'clock. Here is a photo sequence from Richard Sachs, link Many builders put a reinforcing plate at the ends

If you are having a framebuilder do this, he will want you to fill out a questionnaire that would spec internal routing. Most builders use bikecad, and that detail doesn't show up on the drawings, it's on a list of specs.

There are people that use internal routing for the derailleurs, but I would not do that myself due to the requirement to unnecessarily pierce the downtube. The top tube really isn't compromised by the internal routing. There have been corrosion problems when companies have taken shortcuts, but everyone uses a tube to fully sleeve the cable nowadays.

Disk brakes get close to tying you into straight fork blades and 135mm rear spacing. If that's ok, there is no real problem