Bicycle Mechanics - Do i really need this part?

Just finished assembling my new road bike and found this part in the bag of random parts:

https://lh4.googleusercontent.com/-B7CvGXH5ozo/TmgrWInn3iI/AAAAAAAAG10/EpvjF4AK3U0/s800/2011-09-07_19-34-37_693.jpg

Shown here attached to a bike to house the front brake cable, fit right in the cable stop:

https://lh4.googleusercontent.com/-DNGKWYQLs-4/TmgrMaGig-I/AAAAAAAAG1w/_XJH8rjGJGg/cycblkbar.jpg

Not entirely sure why it's necessary but have some guesses. Can anybody make sense of this for me that's assembled one before?

Thanks

Oh yeah, I just realized that since I already trimmed the cable I probably couldn't fit it on now anyway. So unless someone tells me I'm going to be sorry if I don't install it i'll just do without. Lesson of the day- look at all the parts and know what they do before you start.

Nope, you'll be fine, it is just a cable guide. As long as the cable runs freely and smoothly in the way you have it set-up now don't worry about it.

Is it 100% necessary? No. But it does reduce friction on the front brake cable, which will improve brake performance. If you have a lot of spacers between your stem and the cable hanger you should be OK. If they are close, then you may want to add it. As long as you didn't trim the brake cable too short it should be pretty easy to take it apart add that piece (just trim the housing if there is too much left). A new brake cable is pretty cheap as well, might not be a bad idea to replace it and get it done right.

PS... If the bike has canti brakes and all the cables run down the top of the top tube, it's a cyclocross bike, not a road bike.

I guess I just can't see how this could possibly make any difference with friction as opposed to just running the housing. If anything it seems another part would just give more opportunity for friction to happen. ¿Qué sé yo?

I guess I just can't see how this could possibly make any difference with friction as opposed to just running the housing. If anything it seems another part would just give more opportunity for friction to happen. ¿Qué sé yo?

Housing isn't designed to bend so sharply, so this piece allows the sharp bend to get under the stem while avoiding the problem.

I'd take the trouble to install the part. It's asking a bit much of the housing.

Housing isn't designed to bend so sharply, so this piece allows the sharp bend to get under the stem while avoiding the problem.

+1, the friction may indeed be less of an issue than the stress placed on the housing itself, it will be more vulnerable in the event of a small wreck and the plastic coating on the housing will likely split, exposing the steel inner winding to the elements before the liner of the housing is past its useful life, a waste really.

But of course, if your housing does not experience any severe bends as it is set up now, there is no need to include the part in question. Good luck!

Cheers
lverhagen