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I've just picked myself up a Specialized Allez Sport 2014 road bike from Evans Cycles (UK).

I test rode the bike and I'm happy with the bike, but when I got home, and flipped the bike over to make a note of the serial number (for insurance) and I noticed that the derailleur cables cross over on the underside of the down tube.

Down tube derailleur cable cross over

The groupset on the bike is Shimano Sora, installed by the workshop at the Evans store, before I test rode it. Full specs can be found here: http://www.evanscycles.com/products/specialized/allez-sport-c2-2014-road-bike-ec052507

The is the first road bike I've owned with a Shimano groupset < 105 and I wanted to know if this is the normal way to route derailleur cables with Sora shifters?

I have owned a 105 groupset equipped bike in the past with externally routed cables and the cables weren't crossed over on that. My current race bike has internally routed cables, so I can't even check against that.

The potential issue I'm concerned about with the cables crossed over is that through rubbing against each other, they will wear more than they would normally. I'm also worried that the cables will be more likely to rub against the downtube, but I could just be being paranoid...

UPDATE: It looks like I'm not the only person to ask this question: http://forums.roadbikereview.com/components-wrenching/crossing-derailleur-cables-downtube-243700.html

It would seem (from the above discussion, at least) that this is not uncommon for Specialised bikes to cross over.

Still doesn't sit right with me though...

  • Nope, that's not normal, they should be parallel. It's a trivial problem to solve, though, just a case of rewiring the gear cables. If the bike is new, you have a good case for taking it back to the shop and asking them to do it - they'll have cables to hand and it'll only take someone half an hour. Unless maybe the shifters have been swapped around....but that would be strange and even then, the unshielded cables shouldn't cross. – PeteH Nov 11 '14 at 21:49
  • Indeed, the bike is new as I mentioned in the question. It's annoying that I have to make another journey back there for such a trivial issue. Can you think of any reason why they would do this? I can't help thinking they did it for a reason... – JoeNyland Nov 11 '14 at 21:52
  • Just to clarify...the left shifter is working the front derailleur, the right working the rear? I mean, that's convention. You sometimes get brakes swapped around ("British" vs "Continental" setup) but I haven't seen that with gears. – PeteH Nov 11 '14 at 21:55
  • I think someone started mis-routing the cables and then continued cause they had started that way. – Batman Nov 11 '14 at 21:56
  • @PeteH Yes, that's correct. The gear levers are in the usual "British" layout - rear derailleur controlled by the right lever and the front derailleur controlled by the left. – JoeNyland Nov 11 '14 at 21:58
18

This is one of those questions that can start arguments between bike mechanics--to cross or not to cross the derailer cables. Crossing appears to be becoming more common on new bikes, if the cables aren't internal, but it's also going to depend upon the bike. Smoother shifting is reported by some from crossed cables. I would talk to the mechanic at your LBS about it. There could be manufacturer recommendations or anecdotal experience driving the decision.

  • Agreed. The more I look into this, the more it seems to be a conscious decision to do it that way. There also seems to be specific mentions of cables being crossed like this on Specialized bikes too. – JoeNyland Nov 11 '14 at 22:36
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    +1, I stand corrected. I've not come across this before – PeteH Nov 11 '14 at 22:46
  • Most of the major manufacturers ship bike to shops with the cabling already routed. If your ride looks like this, check the rest of them in the shop, they probably all look like that because Specialized shipped them that way. – Deleted User Nov 12 '14 at 0:29
  • Note that routing this way keeps the cables more "inboard" and less likely to get hung up on something. – Daniel R Hicks Nov 12 '14 at 12:16
  • By what physical mechanism would crossing the cables make shifting smoother? – David Richerby Nov 12 '14 at 15:58
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I have seen this frequently and routed my cables this way. By routing the shifter cable from the right side of the handlebar around the stem to the cable boss on the left side of the frame (and visa versa) I create a more gentle bend in the in the cable housing. A gentler bend creates less internal friction on the cable. Another benefit is less stress on the cable ends where they insert at the shifter body and frame boss.

  • Crossing used to be more common on smaller frames which had shorter lengths of housing from the shifter to frame stop than larger frames. One reason, this is seen more frequently on newer bikes is because cables on road bikes are now usually routed under bar tape. So all sizes have shorter lengths of free housing. Before index shifting, the same type of housing was used for both brake and shift cables. Compression housing, aka SIS/index, now used for shift cables is stiffer than wound housing. And the plastic is also more brittle. Another reason you want less stress on the cable housing end. – vlieg Nov 17 '14 at 21:12
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This setup is used less for reduced friction (although many make this argument) and more to keep the cable housing off the head tube so that you don't damage the paint. For example, running the right shifter cable to the right down tube cable stop, this forces the cable housing to make a sharper bend forcing the cable housing to rub the head tube. If we run the right shifter to the left down tube cable stop, the bend is more gentle and the cable housing does not contact the head tube unless the handlebars are turned to extreme angles.

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