REAR DERAILLEUR CABLE ROUTING AND ADJUSTMENT

On Co-Motions having lateral tube shift cable runs, route the cable from the right shifter down the right side of the lateral tube.  Most tandems generally route the cable along the down tube hence the relaxed cable bend will have less friction hence the directions below assume the most common configuration.

1) As the cable and housing leave the left shifter, it should route over to the right side of the frame to the adjusting barrel or cable fitting located at the top of the down tube or on the head tube. The right lever cable and housing should conversely go to the left side of the frame. Routing the cable to the opposite side results in a long graceful bend and optimal smooth cable operation. By routing the cable in this fashion, the cable housing generally will not touch the paint thus preserving the finish.

2) Run the cables down to the captain bottom bracket with the cable from the left lever going through the right hole and the cable from the right lever going through the left cable guide. The cables should be parallel with each other along the down tube.

3) The cables actually cross and make an X underneath of the boom tube(s) as they head toward the next guide. The cable from the right lever threads through the far left guide below the captain's bottom bracket and then crosses over to the far right guide under the stoker bottom bracket.  It then progresses on to the rear derailleur. The cable from the left lever now crosses over to the middle hole and on up to the front derailleur.

4) Insure that all housings and fittings are properly seated in their respective fittings.

ADJUSTMENT PROCEDURES ASSUME PROPER DERAILLEUR HANGER ALIGNMENT AND LIMIT SCREW SETTINGS, SMOOTH, LUBRICATED AND NORMAL FUNCTIONING CABLES AND NO EXCESSIVELY WORN EQUIPMENT.

1) Test the gearing to insure proper function. It should work without readjustment if everything is installed the same way each time the unit is assembled and reassembled.

2) If shifting is less than satisfactory, look at the rear derailleur from behind and see if the two jockey pulleys form a line parallel to the side of the wheel. Everything should be in the same plane. Damage to the derailleur hanger usually will result in the rear derailleur being tipped in whereby it will be noticeably canted with the lower jockey pulley closer to the mid line of the bike than the upper one.  Removal of the rear derailleur during packing or shipping usually prevents this from happening.

You may skip this step for minor adjustment associated with cable stretch and a gradual loss of function. Include it if cable replacement has been made.

1) Shift to the smallest cog, turn the derailleur adjusting barrel clockwise which effectively lengthens the cable by shortening the housing. Run it in all the way and back it out 1/2 - 3/4 turn.  By backing the adjusting barrel out a bit, we have allowed for adjustment either way with the user friendly adjusting barrels but have left plenty of adjustment for future cable stretch.

2) Loosen the cable anchor bolt and pull the cable taut (remove the slack) with a pair of pliers and tighten the anchor bolt. Shift the unit a couple of times, return to the small cog and double check the cable to insure the slack is still absent.

Now proceed to the 'Minor Cable Adjustment Procedure'.

Start here for minor adjustment. Again, this assumes proper derailleur alignment, lubricated cables, proper limit screw settings and no excessively worn equipment.

CHECKING BASIC CABLE TENSION

1) Shift to the largest cog on the rear wheel while on the big chainring. The cable needs to be tight enough for the chain to climb onto the largest cog and stay there. If the cable is not tight enough for the chain to remain on the large cog, turn the adjusting barrel CCW to tighten the cable.

If it takes more than a twist or two, you may want to perform the Major Adjustment Procedure if you have not already done so to prevent using up the adjusting barrel travel. It is nice to have the convenience of the adjusting devices should you need to compensate for cable stretch while on the road.

2) Once the chain remains on the largest cog, shift to each smaller cog successively and observe whether it clunks down with little or no hesitation. Ignore any hesitation dropping off of the largest cog while on the big ring as this is often a normal characteristic.

If it hangs and hesitates dropping to one of the smaller cogs the cable is too tight hence you should skip to the the 'Optimizing' step below. 

MAKE THE CABLE TOO TIGHT

What we want to do now is make the cable too short or too tight and then reverse the procedure gradually for optimal fine tuning.

1) Shift to the big ring and the large cog combination. Turn the adjusting barrel on the rear derailleur two or three good twists counterclockwise to lengthen the housing which effectively shortens the cable. You may also use the barrel on the downtube should your bike be equipped with one.

2) Shift from the largest cog to the next smaller one. If it hangs and does not shift or shifts down but makes a rattling chain noise against the big cog, we have accomplished exactly what we want. Continue to tighten the cable until the chain hangs or does not shift far enough to the next cog for smooth operation.

At this point you should now have the chain hanging on the big cog or barely coming off with protesting noises evident after the shift or attempted shift.

OPTIMIZING THE CABLE ADJUSTMENT

1) Shift back to the big cog while on the big ring. Turn the adjusting barrel back in (CW) 1/8 turn and retest. Retest the shift from the big cog to the next smaller one, to the next smaller one, etc. through the entire range.  Ignore any hanging tendencies from the largest cog while on the large ring as this is not really a problem.

Continue to retest the shift with each 1/8 CW turn of the adjusting barrel until the chain drops off each and every cog to the next smaller one without hanging or undue hesitation.  It may work very well with very little hanging and chain noise except for one particular cog.  Again, if it hangs off the big cog to the next smaller one just ignore it. If you do have one shift hanging up somewhere in the middle of the cogs, turn the barrel in another 1/8 turn and retest. As soon as you have it adjusted to where it will drop off every cog with little or no hesitation and little or no chain noise, you likely have it set close to ideal.

2) Recheck while on the middle ring. You will generally find the shifting response to be faster while on the middle ring since the rear derailleur is positioned differently now that it is required to take up more of the chain. Any hanging experience dropping off of the largest cog should be gone while in the middle ring.