Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

How to tell if a frame was made for crossed shift cables under downtube?

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

How to tell if a frame was made for crossed shift cables under downtube?

Old 02-21-24, 06:45 AM
  #1  
Senior Member
Thread Starter
 
soyabean's Avatar
 
Join Date: Feb 2022
Location: GMT-5
Posts: 879
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 490 Post(s)
Liked 395 Times in 263 Posts
How to tell if a frame was made for crossed shift cables under downtube?

This isn't a question about wheter crossing shift cables under the downtube is better or not, I believe any owner can do whatever they want.

I want to know if there are ways to tell if a frame was made for crossed cables from the factory.

I think if crossed cables touch the downtube then it's a sure no. Because that surely adds friction which impedes shifting.

If crossed cables to not touch the downtube, that does not necessarily imply it was made for it.

And what about crossed cables that are almost touching? I've done setups where I swear were like half-millimetre away from rubbing. Is there a standard acceptable distance? I can't find this data published anywhere.

I've also seen frames where the rear brake cable runs along the left of the top tube, opposite from the rear brake lever on the right. The rear brake housing benefits being loose and open in front of the headset, giving a tighter and responsive braking. However, that does not imply this frame's shift cables are to be crossed. They don't require nearly as much force as brakes.

Maybe this is manufacturer specific? Some bikes were designed with crossed shift cables, others not?
Attached Images
File Type: jpg
crossed cables.jpg (101.8 KB, 78 views)
soyabean is online now  
Old 02-21-24, 07:23 AM
  #2  
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 8,115
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 942 Post(s)
Liked 656 Times in 370 Posts
For me, the deciding factor is how cleanly and neatly the loop from the levers to the down tube can be made. This can be affected by the shape and length of the handlebar, the length of the stem,and the position of the stops on the frame.
If it all fits neatly on the same side of the frame as the lever, I don't cross them
Otherwise, I don't hesitate to cross them under the down tube as long as it can be done without the bare cable touching the frame.
Dan Burkhart is offline  
Likes For Dan Burkhart:
Old 02-21-24, 07:58 AM
  #3  
Senior Member
 
Kontact's Avatar
 
Join Date: Apr 2011
Posts: 6,952
Mentioned: 41 Post(s)
Tagged: 0 Thread(s)
Quoted: 4339 Post(s)
Liked 1,525 Times in 995 Posts
I don't think anyone is making bikes with crossed cables in mind. The ones where it works have the stops in the lower 90 degrees or so of the tube, but I have seen it work even higher up that that.

Generally, you can sight along the stop to the BB, and if you can see the opposite BB guide it will work fine.
Kontact is offline  
Likes For Kontact:
Old 02-21-24, 08:02 AM
  #4  
Senior Member
 
Join Date: Jan 2009
Location: San Diego, CA
Posts: 3,661
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 836 Post(s)
Liked 1,058 Times in 742 Posts
I'm not really sure any are specially designed to be crossed. IME routing depends on various combos of bars, bar height, stem lengths, type/model of brakes, etc., that make cross-routing function better.

Last edited by Crankycrank; 02-21-24 at 03:32 PM.
Crankycrank is offline  
Old 02-21-24, 08:31 AM
  #5  
Senior Member
 
Steel Charlie's Avatar
 
Join Date: Apr 2009
Posts: 923
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 369 Post(s)
Liked 526 Times in 278 Posts
Why is this a thing?
Steel Charlie is offline  
Old 02-21-24, 08:33 AM
  #6  
Senior Member
Thread Starter
 
soyabean's Avatar
 
Join Date: Feb 2022
Location: GMT-5
Posts: 879
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 490 Post(s)
Liked 395 Times in 263 Posts
I understand that even if the frame allows for it, a setup on the bar may not.

Here's an example of all cables entering at the other side, shift and rear brake.
Attached Images
File Type: jpg
crossed-cables.jpg (90.4 KB, 61 views)
soyabean is online now  
Old 02-21-24, 09:57 AM
  #7  
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 18,056

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4194 Post(s)
Liked 3,837 Times in 2,295 Posts
Originally Posted by Steel Charlie
Why is this a thing?
See post #2 for the answer. being a small guy (and making frames for other small riders) the amount of open casing between the handlebar tape exit to the frame stop is usually fairly short, less then on larger sized bikes for sure. I want a handle bar be able to swing fully from tup tube contact to top tube contact (or caliper to down tube) without the casing being stretched too far or having to be really droopy when steering ahead.

In my world there's no issues with cables touching each other at the mid point along the down tube. The cables are under low tensions and are not continuously moving. I'll thread them through a short piece of inner cable liner where they cross each other, to keep them neat and lessen any frame pinging.

I started doing this as I deemed better 30ish years ago. Had a friend that on unpacking their bike from my shipping it to them (after some service on it) couldn't figure out how to "untangle" the cables and ended up going to a shop My mistake was not telling them of this routing change I had made. Andy
__________________
AndrewRStewart
Andrew R Stewart is offline  
Old 02-21-24, 10:46 AM
  #8  
Senior Member
 
Join Date: Mar 2012
Posts: 978
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 504 Post(s)
Likes: 0
Liked 635 Times in 355 Posts
Originally Posted by soyabean
I think if crossed cables touch the downtube then it's a sure no. Because that surely adds friction which impedes shifting.
While you are surely correct that it adds friction compared to a cable that doesn't touch, the amount of friction it adds is surely negligible compared to all the other friction in the cable system. I cross cables under the down tube because it makes for better routing off the handlebars.
KerryIrons is offline  
Old 02-21-24, 10:58 AM
  #9  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,660

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5766 Post(s)
Liked 2,537 Times in 1,404 Posts
You are w-a-a-a-ay overthinking this.

It's very simple. Feel free to cross them as long as they don't touch or rub. This isn't horseshoes, so close doesn't count.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

Just because I'm tired of arguing, doesn't mean you're right.

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Old 02-21-24, 11:12 AM
  #10  
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 8,115
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 942 Post(s)
Liked 656 Times in 370 Posts
Originally Posted by FBinNY
You are w-a-a-a-ay overthinking this.

It's very simple. Feel free to cross them as long as they don't touch or rub. This isn't horseshoes, so close doesn't count.
I don’t worry if they touch or rub each other because the contact is very light. I prefer they don’t touch or rub the frame.
Dan Burkhart is offline  
Old 02-21-24, 12:28 PM
  #11  
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,800

Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1943 Post(s)
Liked 2,164 Times in 1,323 Posts
I use the rear derailleur cable loop as a guide. If my shifter to stop minimum radius is less than what I would use for an RD loop, I might consider cross cabling.

Of course this is at a minimum riding radius, not handlebars at 90*. That would indicate a whole lot of other catastrophic problems, especially if done at speed.

John
70sSanO is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.