How to replace rear brake cable on 1990's GT Tequesta?

[Sham69]

Anyone know how to replace a rear brake cable on an old GT Tequesta? Advice and suggestions gratefully received.

I'd like to remove the brake cable to clean it up or replace - depending on what I find. Problem is, the sheathed brake cable disappears into the frame (top tube) at the front and the inner brake cable (wire) emerges through a very small hole at the rear end of the top tube. I've no idea what arrangement GT used to guide the cable inside the top tube, if anything, so I'm reluctant to pull out the cable until I better understand the arrangement because I may be unable to return it. And if I can't physically return or replace the cable, I'm looking at a whole new rear brake setup.

I have the same bike as this:
http://si6.mtb-news.de/fotos/data/16420/IMG_6546.JPG

Whilst you can't quite see the cable disappearing into the front end of the top tube, you can see the inner wire emerging at the rear end. Thanks for reading.

 

[Jameshow]

Fishing line tied to the old cable, pull it out and tie other end to new cable and pull through. Tiny bit of insulation tape to hold the cable close to the line.

 

[boydj]

Fishing line tied to the old cable, pull it out and tie other end to new cable and pull through. Tiny bit of insulation tape to hold the cable close to the line.

And pull gently so as not to lose your fishing line (or strong thread).

 

[Cycleops]

This is a useful hack using cable end cap, or you could use a ferrule:


View: https://youtube.com/shorts/B449ew43gus?si=ErWqOmHAyC51hqx9

I should replace both inner and outer.

 

[cyberknight]

when i did my boardman i literally glued sewing thread to the cable and pulled it through, then glued a new one on and pulled back

 

[Sham69]

Thanks for your responses - appreciated.

I get the gist, however, the hole in the rear end of the top tube (through which the rear brake cable wire emerges) is truly small - just large enough for the wire only. Certainly couldn't use a ferrule or cable end cap or tie fishing line to the wire at the rear end and pull it through from the front. Maybe sewing thread would be sufficiently fine - I'm amazed the glue held though. Will give it some thought.

I obviously can't see inside the top tube but I imagine the outer sheath continues inside, along the length of the top tube, and the tiny rear end hole holds the sheath back, just allowing the wire itself to pass through to the brakes.

I'll upload some photos tomorrow so you can see what I mean.

Does this type of arrangement get the award for design stupidity or are there even worse examples out there?

 

[Drago]

Leave inner in place, slide out the outer. Slide a new outer on over the old inner. May take some wiggling at the other end, but it will go.

With the new outer in place you can then release and replace the inner.

 

[Sham69]

Thanks Drago. My only concern about this method would be if the cut end of the new inner wire started to fray as I wiggled it along inside the sheath. I'm not sure how smooth the inner surface of the outer sheath is. Also, I'm assuming that the outer sheath travels all the way along inside to top tube until just before the point where the inner wire emerges at the rear end of the top tube. This is a job that will likely be required at some point, however...

I've discovered two more rear brake problems I didn't know I had.

I should have checked over the bike more thoroughly when I last had an accident on it (came off at a roundabout on black ice a few years back). Only just noticed uneven brake block wear on one side. Turns out the right side brake arm lever had taken a hit and whilst the brakes still worked OK, the mounting post to which the right side brake arm attaches is marginally out-of-true which means the brake block no longer sits flat on the rim (and cannot be adjusted to do so). Can't do much about this, I guess, without paying for an engineering repair - not worth it on this, my secondary bike. Will get through a few more brake blocks but as it's a low mileage bike, not a big deal.

Second problem frustrated me for hours. I didn't understand why I was unable to adjust the spring tension sufficiently in the back brake arms. Every time I raised the spring tension in the brake arms to keep the brake blocks well away from the rim, the arms began to jam up. Took ages for me to realise that the springs, one on each side, were not identical. The two springs were wound in opposite directions so each needed to be fitted to the correct side - and they weren't. I overhauled the bike last year and, because I thought the two springs were identical, must have returned each spring to the wrong side so instead of the spring "tightening up" when the brake arm tension was increased, the springs "opened up" to the point where they started to rub/jam against the inside of the brake arms.

The main reason I wanted to replace the rear brake cable was to minimise friction as I thought the cable had gummed up. Well, it may have a little but it seems the main problem was the resistance in both rear brake arms due to incorrect springs, which is now sorted. As the brakes work fine, I'll postpone replacing the rear brake cable but will bear in mind your helpful suggestions for when I need to do so.

Many thanks for your input.

 

[Tail End Charlie]

How strange, I have a GT Tequesta ( bought new in Nov `95) and the rear brake cable just runs under the top tube (which is contoured to accept it) so it's a doddle to replace. Wonder why they decided to make it more difficult?

 

[Cycleops]

You shouldn't worry about the cable fraying, new cables are treated at the end to stop them doing this.
I should try manipulating the damaged brake post to realign it. You can also replace the post mount.

 

[Sham69]

How strange, I have a GT Tequesta ( bought new in Nov `95) and the rear brake cable just runs under the top tube (which is contoured to accept it) so it's a doddle to replace.

I bought mine second hand in the early 1990's. Maybe GT received complaints so revised the design for the following Tequesta model.

You shouldn't worry about the cable fraying, new cables are treated at the end to stop them doing this.

Ah, OK. Thanks for that.

I should try manipulating the damaged brake post to realign it. You can also replace the post mount.

Truth be told, I did try to realign - with a stout piece of wood and a club hammer (wasn't going to admit to that!)! Unfortunately, it didn't change anything. Thing is, the right side rear brake arm post is only very, very slightly out of true so it's difficult to notice it by eye, but even being marginally out of true seems to have an amplified effect on the brake block alignment - with brakes applied, one end of the rear right side brake block sits about 2 to 3mm from the rim.

I gave thought to other methods of straightening the brake fixing post, such as some sort of leverage arrangement, but I'd need to strip down the rear end of the bike (rack, mudguards, wheel) to give myself enough space. Also, whatever method I use could break the post and that may well be the end of the bike - or a specialist repair job (£££!).

Yes, it looks like the rear brake fixing posts are screw-in but I'm not certain. I've tried unscrewing them but can't grip the posts securely enough without risk of chewing up the post's surface. And it may be the frame fitment (that the brake fixing post screws into) that is marginally out-of-true, I can't be certain either way. I should probably consult a relevant engineer as there may be other possible straightening methods I haven't considered.

For the time being though, the brakes are effective (in wet and dry conditions) so I'll leave as is. The blocks will wear down soon enough so that the entire brake block surface is in contact with the rim.

Many thanks again.

 

[Cycleops]

Yes, it looks like the rear brake fixing posts are screw-in but I'm not certain. I've tried unscrewing them but can't grip the posts securely enough without risk of chewing up the post's surface. And it may be the frame fitment (that the brake fixing post screws into) that is marginally out-of-true, I can't be certain either way. I should probably consult a relevant engineer as there may be other possible straightening methods I haven't considered.

The posts will be screwed in unless it's a very cheap frame, which yours isn't. Use a vice grip wrench to grab the post.

 

[Sham69]

The posts will be screwed in unless it's a very cheap frame, which yours isn't. Use a vice grip wrench to grab the post.

I have wrenches that should do the job but I think there's a moderate chance of damaging the post's surface, so I'd only attempt this if I had a replacement post to hand. I've searched for one but can't find any - maybe I'm looking in the wrong places? Any hints and tips on locating one of these posts will be gratefully received, thanks.

 

[Cycleops]

AliExpress offer them but your best best would be eBay.

 

[Sham69]

AliExpress offer them but your best best would be eBay.

Hadn't thought of AliExpress. Thanks. I'll keep an eye out for any on ebay.