Spritelover

Hi guys,

My bike stopped shifting a few months ago. I am a proud owner of a '74 Raleigh Sprite.
What happened is that my gear cable had snapped ( the inner cable).The outer cable is in mint condition. The gear mechanism is a Shimano Positron 400 5-speed btw.
I have ordered a new gear cable, took the old one out, and, to my surprise, there seems to be a bit where the gear cable seems to get stuck: When inserting the inner cable, the cable gets stuck at about 3/4 of the outer cable length. It is impossible to push it any further, but it can still be pulled out. Same story if you insert it from the derailleur side. It doesn't come out the other end, which leaves me worrying, because this bike is the only way for me to go to school nowadays, and it costs all my might to keep the bike moving ( stuck in top gear ). I cant remove the cable from the derailleur, it seems that the connector has been built around the cable. I have tried straightening the cable but again no result.

Could anyone please help me?

Thanks in advance,

Spritelover

randyjawa 

Cables, like brake pads, and chains are wear items. The best advice I can offer is to replace both the cable and the cable casing. Trying to smooth out an old, perhaps bent, or frayed, or oxidized cable and its similarly aged/used casing is not a very good idea.

The new cable and casing will dramatically improve the shifting action.

Spaghetti Legs 

That is a mystery if the original inner cable came out intact, but not one that should be agonized over. The outer cable is done for and you just need to replace it. Not an expensive fix.

Pars 

Do you mean you can't remove it from the shift lever? If so, it is a barrel end on the cable. You should be able to knock or pound it out. You will probably need to remove the lever from the band that holds it on (downtube? stem?). Keep track of any washers or hardware and their order and orientation.

Did the old cable break inside the housing or in an exposed section? At any rate, using new modern housing with a teflon liner (they come that way) will be a vast improvement. If it were mine, I'd probably just replace all cables/housing at the same time, with modern stainless steel cables and lined housing.

oddjob2

Buy this kit at Walmart, Ace Hardware or Dicks. Change all your cables and you will be happy.

Bell Sports 1002283 Basic Bicycle Tune-Up Cable Kit - Walmart.com

oddjob2

A heavy duty linesman's pliers will speed the install or go to your local coop.

Bianchigirll 

Actually I believe for the OPs Positron shifter she/he needs a special cable that is like a solid wire rather than a flexible multistrand cable. I also believe it comes with housing as unit.


OH my mistake you can get just the inner wire but they are pricey. Vintage Shimano Schwinn Positron Inner Gear Cable Bike Bicycle 5 6 10 12 Speed | eBay

$19.99

Spritelover

Hi,

Thanks for all the replies about my bike. I think I am going to see a specialist who is not so far away from my house tomorrow. He might give me some advice. The problem in removing the cable is that I find it hard to remove the clip which holds the outer cable into the derailleur ( don't want to use excessive force, cause I'm really concerned about doing something wrong). Positron outer cables aren't available here in the Netherlands, and I still need to see whether I can order the right cable. As for Bianchigirll, I already have an inner cable. Got it from an online store here for only $2,50!!! Such a steal! The only cables available are red, but mine is black. I really dont want a red cable, because that would ruin the look of the bike imo (My brake cables are black too, and the bike is white...). But i will consider purchasing a new outer cable. Thanks once again for all the advice!

Spritelover

Grand Bois

The "outer cable" is called cable housing.

zukahn1 

+1 The OP's bike likely has a first generation Positron which took specific parts which are hard to find, pricey and don't work real good. To repair one of these to use as a daily rider I would suggest that the OP replace the positron stuff with a standard friction derailleur and shifter it will likely be cheaper and well be easier and work better.

SJX426 

Don't know if this will help or not but you got me curious!
Shimano Positron 400 derailleur (DG-300)

CliffordK

Sometimes one can get a rust spot in the cable housing which can cause problems, especially if there is a low spot in the routing. Was the old cable badly rusted at some point? Little nicks in the plastic covering for the cable housing can also spell it's demise.

Grease can sometimes help.

Nonetheless, the replacement housing is cheap, as long as you can get a close enough match, and that is probably what I'd do.

Your mechanic will probably also recommend a new cable housing as he will also lack patience with trying to force cables through a housing that isn't good.

Spritelover

Hi guys,

Thanks for the advice. I have been to the bike specialist near my house, who knows a lot about classic bikes. He told me that it is better to replace the cable housing, but he also recommended to cut the piece of the housing off, route the cable through, and cover the open part with a transparent film. He recommended the latter because the housing for the particular part is not very cheap here, let alone available. I will try to find a cheaper housing, and see. CliffordK: I don't believe the cable is rusted, at least it doesn't look like it. From the exterior it looks new, but from the inside it could be rusted, because it was originally fitted by Raleigh, so for a 40-year-old cable it can't be excluded.
Thanks again,

Spritelover

wrk101

Very few bike experts know anything about positron cabling. It has been obsolete for well over 30 years

Bianchigirll 

I had a Positron bike a few years ago and was afraid to do much to it for fear of breaking something.

Homebrew01

I wouldn't be surprised if Positron housing has a larger inner diameter than regular housing. It might also be constructed differently. Regular housing is fairly cheap, so you could take the positron cable to a bike shop, see if it will fit inside, and if so, give it a try on your bike.