cango

I am in the process of updating my vintage Trek Multitrack. I picked up a Jones H Bar and I want to replace the SRAM SRT400 Gripshift with Shimano Deore DX thumbshifters (new in the box). Plus I want to swap out the cantilever brakes for Avids. I got new levers and brakes. Yes its not trivial but its better than $1500+ on another bike.

I also picked up a Pedro cable puller and Park cable cutter.

Over the weekend I started to disassemble it and was interupted by my wife and kids so I put it back together. There was no way in the time I had that I could finish the job of cutting the cables, etc...

Anyway after I reattached the cable to the rear derailleur it just would not shift. The bike was in the smallest gear. I played with it for a while and than finally after pulling the cable very tight it shifted. Rode it today and it shifted but not great. Seemed hard at times. Even before I started weorking on it, it shifted eh - I realize its old and the cables are probably stretched out.

I have watched a ton of videos on ths so I am not sure what I am doing wrong. I am very mechancally inclined and have rebuilt cars, renovated kitches and baths. So I know my way around tools.

I would have thought that considering its the same cable and I did not touch any settings on the derailler and shifter, just reattaching it would be good to go. There is more to this than I realized.

Are there any tips that I am missing?

I am now somewhat fearful of doing the whole enchilada - shifters, brake levers and brakes. This is my only bike and dont want to ruin it considering how long this pandemic may go.

ramzilla

Rear derailleurs are hard to remove because you have to break the chain to get at them. My advice would be to go ahead & break the chain off & remove the rear derailleur. Soak RD in penetrating oil & clean it up like new. Re-mount it & install a new chain with a "quick link" like a KMC x-8.93. With a little elbow grease & a new chain, I bet you won't have any more shifting problems.

cyclist2000

I don't break the chain to remove a rear derailleur, I remove the lower pulley on the RD then the chain pops out of the derailler.

Litespud

the rd cable has to be very tight - absolutely no slack, or half the shifter movement will be spent taking up cable slack before the derailleur starts to move. Start by screwing in all the cable adjusters (shifter and rd) almost all the way in. Pull the cable tight - if I’m installing a new cable, I wrap it around my fingers to get a good grip, if an old cable, I might use vise-grips to get some tension on it. Screw down the clamp. No matter how hard you pulled it, it won’t be enough. You’ll now need to back out one or both of the cable adjusters to get more cable tension. At this point, it should start to behave. I like my der cables to be “guitar string tight”, but it gets me good crisp shifting.

cango

Got it, thanks! Thats the kind of info that I was looking for. None of the videos I have watched have said anything about the tension like that.

As for degreasing the derailer, I think I can do that on the bike. This bike was always taken care from a cleaning standpoint but the grease is probably old and gummy at this point. I willl use wd40 or pblaster to clean it.

noimagination

You and Litespud have identified the most likely problem - cable tension.

Other things to consider:
- If the cable housing hasn't been replaced in a while, there could be gunk in there interfering with cable pull/release. If the shifting was good at one time and has deteriorated over time, along with the cable tension issue mentioned by you and Litespud, gunk in the housing is another possible issue. Presumably when you switch over to the thumb shifters and replace the cables you will also replace the cable housing.
- If the housing from the housing stop to the RD has too sharp a bend, it could kink the cable and interfere with cable pull/release. OTOH, if the bend is too big, the housing could flex too much when shifting causing missed shifts. If the shifting was good when the housing was new, though, this is probably not an issue.
- If you use electrolyte replacement (Gatorade or the like) in your bottle, then over time drips can gunk up the cable run under the bottom bracket. Rinse the BB area with water and let dry.

There are other possible causes of difficulties shifting (derailleur limit screws not set correctly; wheel put back in improperly - not seated in dropouts correctly; bent dropouts/misaligned frame; bent derailleur hanger; broken shifter internals; improper cable routing) that don't seem to apply, since you just disconnected and reconnected the cable without changing anything else.

ofajen

First a reminder to make sure the chain is on the small sprocket and the rear shifter is set for the small sprocket, turn the cable adjuster back in (loosened) and then try to install the cable with enough tension to take out the slack while you tighten the clamp on the cable.

But in my experience old rear derailleur cables can be cranky to re-install. They tend to get mangled by the clamp and may tend to fray. Sometimes I’ve had to replace the cable just because it would no longer cooperate and properly fit back in the way a new cable would.

How about you go ahead with the new shifter set up with new housings and cables ASAP? It will be a happier time working with new cables and housings!

Otto

cango

I think you are right about the new cables. When I examined the cables when I was working on the bike tye they are very oxidized - almost black. Anwyay when I started this project I bought new cable kits made by Jagwire for both the shifters and brakes. Has all the bits in them to recable the bikes.

Going to degrease everything over the weekend and take it from there.

SJX426 

cango When you install any cable, test for ease of movement through the housing. There should not be any resistance. Typically you find that the cable will have resistance after cutting the housing. If you insert a trimmed piece of cable in the housing before cutting, the liner will be less deformed. Use the sacrificial cable to expand the liner at the cut to eliminate the resistance. Test again after the housing is fully installed.

Likely the brake housing will collapse because it is a spiral housing. I use a Dremel tool to grind it flat and eliminate the bent part of the housing. Make sure the housing is cut square, otherwise it will feel mushy.

Some advise the shifter housing be cut with the final bend to make sure all the strands of the housing end up being square. This is really important as it may cause your cable tension to vary leading to crappy shifting. Park Tool has a good video

Retro Grouch 

Was it working before you "fixed" it? If so, forget about replacing parts.

Pretty much every bike mechanic in the world has an old cut off spoke that has been sharpened at one end. They use it for re-opening the cable housing after cutting it to length.

When sizing your rear cable housings, turn the handlebars all the way to the side. You'll never turn your handlebars that far while riding, but too short cable housings will cause the shift or brake cable to pull when you don't want it to.

When you go to replace the shift cable, make sure that the chain is on the smallest sprocket and that the gear shifter is in the appropriate matching position (H for the rear derailleur, L for the front derailleur). Pull all of the slack out of the shift cable as you tighten the cable anchor screw.

When you replace your candy brakes, make sure they don't rub the tire sidewall. If they rub the tire sidewall, your next task will be replacing your blown out tire.

ofajen

I use a punch with a fine point. It also works well for this.

Otto