Syncmaster

I just installed new shifter cables and I'm not sure if my RD housing should be shorter. I understand the principles of proper housing length (parallel exit and entry at the stop and the barrel adjuster), and I believe my housing meets these requirements, but my loop looks much larger than most examples I've seen on other people's bikes.

I based my setup on this image from Park Tool:


And here's my setup:




So what do you think? Too long? By the way, the bike does shift very nicely so far after a 30 min session on the rollers.

Thanks so much.

HillRider

If the shifting is good, the loop must be ok but it does look a bit long to me. I checked a couple of my own bikes, which also shift well, and I have a 4" between the far end of the loop and the center of the QR skewer nut on the drive side so see how your compares.

Andrew R Stewart 

Interesting, I cut my housing loops to look much more like the "short" one. Can't say that this length has ever been a problem for me or my customers. far more important then a small length difference is the condition of the cable and casing and whether there's any grime/rust inside them. Andy.

RoadTire 

Pictures of it in the highest gear and the lowest gear? Highest gear, with the derailleur most extended the cable should be going straight into the derailleur cable stop w/o straining or tending to kink, and in the lowest gear has a minimal 's' curve. Yours looks like it would have a bit too much 's' curve in the lowest gear. Note the Park Tool diagram is in the highest gear and you are in a middle gear.

Thumpic

I must be slow......the housing will be in the same relative position/shape irregardless of the gear position. Right?

RoadTire 

Now you made me go back and look a mine, twice. Heh. The housing does straighten some on the lower gears, but not as much as I thought. (2008 10 sp Ultegra FWIW) I suppose a little long is better than any too short. Some bikes I've worked on (older and cheap) seem to move a lot more.


(and your wheels cost more than all three of my bikes, so what do I know?) heh

RoadTire 

nm dbl post.

Thumpic

I think older bikes (especially friction shifted) have a larger "sweet spot" when it comes to shifter housing length. I prefer the smallest loop possible that provides correct shifting; just a personal preference.

cyclist2000

I prefer to have a little too much housing, that way if I need to trim some housing when putting in new cables.

ThermionicScott 

+1, the "good housing" pic looks wack. If the housing is too long, there is extra cable friction since the cable has to go further outward before it can bend around.

Syncmaster

Thanks for everyone's comments. I ended up trimming about 2 inches from the housing and the exit/entry from the cable stop and barrel adjuster still look good. Shifting still feels crisp. I could still probably trim a bit more but I'll see how this rides and then adjust from there.

veganpower

I think it looks fine, as long as the shifting is good then there is no problem. I'd rather be on the long side than the short side.

Looigi

Wrong, IMO. Sharp bend radii cause more friction than longer straighter runs. Erring on the side of longer adds very little friction whereas erring on the side of too short adds a lot. Between the two, I'd go with the long one, but since it is a bit beyond optimum IMO, I'd cut a cm or two out of it to get just right.

RoadTire 

2 inches is quite a bit. Can you post another picture, (or two) one in the same gears as your original and one in the highest gear? Curious to see how much difference it made. BTW: thanks for posting this - good thread.

Syncmaster

After an hour ride the indexing feels good so I'm going to stick with this length. It still even looks longer than a lot of setups I see in person and online but perhaps a lot of people end up cutting cables too short? Here are some more pics of what it looks like now.

In the same gearing as what I posted above:



In the highest gear:


And also in the smallest ring up front/largest in the rear just for fun:

Al1943

Short housings included in kits from Shimano are about 31 cm (12 inches) and from Campy about 33 cm (13 inches). I think this is the normal range for good shifting performance. But whatever works for you.

RoadTire 

Huh. You win. I don't see any real difference in the cable housing bend at the highest or lowest gear either. You are probably right in leaving it alone now - even if (that is a "if") it is long, it's 2 inches less long and looks good. What is odd is that I cannot really see any huge difference in the derailleur position between the before and after pictures. New to me.

Syncmaster

Another poster above measured the distance from the farthest part of the loop to the center of the QR nut and said his was around 4". I measured mine when I thought the loop was large and it was at 5". Now after trimming some excess length the loop is around 4.5"

I think I'm right in the sweet spot now. Interesting that Park Tool provides a reference picture that shows the loop so exaggerated but it also seems like it's a picture of a friction based shifter.

I'm glad I asked here though. I think I always err on the side of being too long when I first setup a rear derailleur but then I end up trimming a bit.

rccardr 

I would say...still too long. Try to make mine flat out of the cable stop, then a 180 bend into the RD. But no harm done unless you find your cable flapping around back there.

Kimmo 

BTW, that's not a real word, FYI.

Thumpic

Iz 2.

RoadTire 

That's funny. heh. I grew up with that word, so didn't catch it, but you are correct, Kimmo.

cycle_maven

It used to not be a real word, but it's now in the American English lexicon:

https://www.merriam-webster.com/dictionary/irregardless

Kinda like my pet peeve word: "entitled" being used in place of "titled", as in "The book was entitled The Grapes of Wrath". Which is more whack than a long cable loop, IMO.

Thumpic

Do you guys go to the grammar forum and talk about bikes? That must be a thrill for you too!!!

RoadTire 

uh, ya?