Subject: Brian... MANY THANKS! I'm off to work on the puppy, now! (nm) Posted by: Quip on December 20, 2002 at 13:38:29: In Reply to: Re: Shift/Brake Housings Dilemma posted by Brian on December 19, 2002 at 22:42:14:

Message: >>hey folks... hoping a few of you can help me out. >>i have a tri-bike set up with shimano aerobar-end shifters (indexed) and i need to replace the shifter housings. i've already swapped out the brake cables without an issue, but as i look at the existing shifter housings, they are as thick (diameter) as the brake housings. sort of looks like the previous owner used brake housings instead of the smaller shifter housings. >Using brake cable housing for shift cables usually results in a significant decrease in performace in indexed shifting systems. Shift cable housing does not significantly change length (compared to brake cable housing) with changes in cable tension. This was not an issue until indexed shifting systems becase the norm. Don't use shift housing for brake cables however as the loads exerted on the housing during braking could cause shift housing to rupture. >You can tell the difference between brake and shift housings by examining the orientation of the reinforcing wire in the cable housing. Shift housing has a set of parallel wires, brake housing has one larger wire formed in a helix. >>the new shift housings i ordered from shimano (SIS) are much thinner. now comparing this to my road bike set up (much newer bike) i see that my road bike has smaller cables for the shifters and larger for the brake. it also appears to only have a metal ferrule in one place: >> on the chainstay housing, only on the end that goes into the derailleur. everywhere else is just the plastic ferrule that came with the cables. >>so back to my tri bike. the shift housings are large and have a ferrule at every housing stop. i'm totally confused. do i have to replace the larger shift housing with a larger brake housing. or do i swap out the big housings for the small housings and if so, do i use only one metal ferrule in the rear derailleur? >Use the new shift cables and shift cable housings for shifters regardless of the diameter of the parts that are currently on the bike. Concerning the ferrules, both the metal and plastic parts will do the same job. Ferrules simply cover the cut ends of the housing and provide good contact for the housing onto the frame when the cable is under tension. The choice of ferrules is completely arbitrary and will have negligible effects on shifting performance. I typically use metal ferrules on the bikes I build as it has a classier appearance. >>one last note, the plastic ferrules are not as large as the existing metal ones... will there be excess room between the plastic housings and the cable stops? >I have found that if the diameter of the ferrule is significantly smaller that the diameter of the mount on the frame (as can be the case using plastic ferrules), a little electrical tape solves the problem nicely. >>many, many thanks! >>Quip >Enjoy the ride... >Brian