TXsailor

We were given a Kuwahara tandem that I am guessing was made in the mid 80's It has a 7 speed freewheel and triple crank and came from the factory with downtube shifters. It has been changed over to Shimano brifters. The brakes are NGC982 cantilever's with new Cool Stop salmon pads. I have watched several U-tube videos and read articles from Sheldon Brown to try to find a adjustment method that will help braking. I have tried changing the length of the straddle cable and shoe adjustments to no avail. It just doesn't stop good enough to feel safe. I can't even lock the back wheel up when riding it single and the front is the same. I have new cables ordered but I don't expect them to help as the old ones seem free and don't have much friction. Unless I have missed something the only thing I can think of is that the rims are too smooth. I have even took a red scotch brite pad and alcohol to them but that didn't seem to change the very slick appearance and feel that they have. They are 27" aluminum that I assume it came with new. It does have the Arai drum brake that was disconnected when they changed the shifters. I have added a friction shifter for it and it works well now. Any ideas? can I take sandpaper or something to the rims to rough them up? My granddaughter & I really like riding the bike but I am afraid I am going to crash and hurt us both.

OneIsAllYouNeed

Those pads are good, and aluminum rims should be good. Those brakes were fairly reputable in there day. Try these, roughly in this order:
There aren't any pulleys or cable travel adjusters in the system, are there?
Lube (grease, silicone, etc) the brake pivots.
Make sure the housing and cables aren't dirty or rusted together. Lube (light oil, chain lube, silicone, etc) the cables where they are inside housing.
Make sure the cable housing ends are cut cleanly and that the ferrules (housing ends) are snug.
Make sure there aren't sharp bends in the cable housing.
Lower the straddle cable as much as possible.
Scuff the pads with sand paper.
Adjust the pads such that they're parallel/flush with the braking surface of the rim when the lever is pulled. 0.5mm of toe-in can help with squealing, but otherwise the pads should be parallel.
If you want to spend $20 for better brakes, Tekro RX5 or Tektro 926 linear pull ("Mini-V") brakes should drop right in.
Another upgrade would be "compressionless" brake housing.

JanMM

I wonder if a large part of the problem is the brifters? Are they supposed to be compatible with canti's? Kool Stop salmon are the go-to pads for most situations.
I haven't dealt with canti's for a long time - I find V-brakes much easier to deal with and are usually easy replacements.

Alcanbrad

Also check the amount of slack in the brake cable (rear). When you squeeze the brake handle, does the handle move before the canti's start to move and once the pads contact the rim, does continued squeezing not add much pressure and just removes more slack from the cable run? If this is the case, you need to figure a way to eliminate the slack

I had this slack issue with my Spyre disc brakes and was only able to resolve by fashioning and installing a compression spring to take slack out of the line. Different brake setup for sure, but similar likely cause as most of the components in the system are designed for shorter cable runs.

TXsailor

New cables & housings on the way. I'll check everything mentioned when I install them. The pads are hitting squarely and pivots cleaned and lubed. I am not against swiching to different brakes in fact I tried a set of caliper brakes that I had from my road bike and they are way too short. I will research the above mentioned brakes when I get home to my computer.

scycheng

I don't think the Shimano brifters will pull enough cable for cantilever brakes when there is long cable run.

I use old 8 speed Ergopower lever with old Shimano cantilever (unknown vintage) on the front and it works fine but the rear never worked well because of insufficient cable pull + long cable run.

We've switch to disk for the rear which has different set of issues.

For brifters, if you have the appropriate mounting holes, long reach side pulls might work better. Rivendell sells at least one long reach sidepull which might work with brifters.

https://www.rivbike.com/collections/...tro-r559-allen

TXsailor

The bike does have holes for caliper brakes. They would need to be long reach.

Alcanbrad

I am not familiar with your bike but make sure that the holes are for brakes and not just for fenders. If they are intended for fenders, there might not be enough strength to withstand braking forces.

OneIsAllYouNeed

TXsailor

How do I tell? The holes are centered in the fork and the bridge between the seat stays just like they are on my Centurion road bike. The top of the fork looks to be a very solid casting with lugs for the forks.

TXsailor

Will the Shimano 7 speed brifters work with them? I am not even sure they are right for the cantilever's that are on there but the lever does move about 1/2 - 2/3 of the way to the bars when I have the pads adjusted about 1/8" from the wheel. They just feel like the old bikes we rode as kids with chrome steel wheels and little brake pads.

OneIsAllYouNeed

TXsailor

I don't remember where I bought the brake pads from but I ordered them from one of the major online bike shops Jensen, Performance etc, a couple of years ago. I installed them then but haven't had anyone to ride the bike with until lately. The bike has been in my garage ever since we got it. I don't know what model the shifters are I don't see a number but they are not like the 105 5700 I have on my road bike. They have the brake cable under the bar tape and the shifter coming out the side. They just say Shimano triple and Shimano 7 speed on them. They use a little vertical lever to shift down and the brake to shift up. They are a blue/grey color. I really like riding this bike with my granddaughter . My wife is having both knees replaced (first one done today) and wants to ride it too. Overall its in good shape and has been well cared for. I just replaced the seat posts with some that adjust, added some bottle cages and the new cables came in today. I don't mind spending some money on it I just want it to stop safely.

Alcanbrad

xlbs

Your pull ratio is probably the problem.

https://problemsolversbike.com/produ..._agents_-_6416

TXsailor

According to the link to the travel agents I have short pull levers and brakes so I don't think they would help. I did replace the back cable and housing today and shortened the housing from the lever to the first cable stop by several inches. I made sure all the ends were square and had ferules. The lever feels firmer and it seems to stop a little better but that may just be wishful thinking. I still can't lock up the back wheel when solo. The lever doesn't touch the bars. I understand that the NGC 982 brakes are well thought of and these seem to be in excellent condition. I am back to wondering about the braking surface on the rims. They are very smooth and look like they have some kind of a grey coating on the entire wheel, its shiny where the brakes run but you can still see the grey. Has anyone ran into wheels that were too slick other than chrome steel wheels?

OneIsAllYouNeed

TXsailor

The rear wheel says UAKI 27 X 1/18 W/O LA MADE IN JAPAN no other markings. I googled them but didn't find much but I am not a expert googler. Is that a word googler? I wonder what a LA is. Whatever it is I guess I don't have one.

OneIsAllYouNeed

"W/O" = wired-on, meaning clincher tires (as opposed to tubular or sew-on)
"LA" supposedly means "light alloy"
Those rims are not likely coated in anything beyond natural oxidation at this point.

TXsailor

Maybe I am just being a wimp and this thing is just plain hard to stop. Since I consider my most likely stoker "precious cargo" I really want to be as safe as possible. I do feel a little better since I got the arai drum brake hooked up to a friction shifter but its not very handy for quick stops. Its more like a drag brake for descents

Alcanbrad

There is nothing wrong with feeling uncomfortable with the way your bike is handling. You need to feel secure in the bikes braking ability.

Our first Tandem has cantilever brakes and when we purchased it we had is upgraded from bar end shifters to STI brifters. We never rode the bike with the original brake set up (other than one test ride around the block) when we purchased it so I had nothing to compare to. We lived in a flat area and I just thought stopping took longer. We subsequently moved to a very hilly areas and I quickly became very uncomfortable with the bikes braking ability on the hills so I added a drum brake. Fast forward 10 years and we buy our current bike with disc brakes and I was very uncomfortable at first not having the drum brake as I did not know how disc brakes performed. Now that I am used to the disc brakes, I would never consider going back to rim brakes, but there are a lot of bikes with them that people ride everyday without problem.

Looking back on it, I probably experienced the same thing you have, namely, changing to STI levels which do not have sufficient pull for the cantilever brakes. (I did have to improve the rear braking of the disc brake with a compression spring as I mentioned above, but with this thread it seems reasonable to assume we did experience the same behavior.)

That said, we never had an issue stopping with just cantilevers, it just took longer to stop. Once we starting riding the hills, we spent a few teeth grinding death grip on the brakes descents that was resolved with the drum.

I have never locked up the rear wheel, nor have I tried. I would suggest you go somewhere flat and without traffic, like a large empty parking lot, and with the stoker, get the bike up to speed and perform hard braking and take measurements of distance to full stop and see how it really is behaving. (For downhill stopping you will always have time to apply the drag brake). If the stopping distance is not to bad, perhaps you can just adjust your riding style to pre-anticpate the scenarios where you might have to come to a quick stop or you might also consider and setting your stoker up with a hand brake lever that controls the drum and work a communication protocol for the stoker to apply the drum brake while you are working both hand brakes. I have heard mentioned several times that on some teams, the stoker controls the drag brake.

reburns

Paul J

I would think about converting the "V" brakes (Shimano's branded name but what most people call them) and use the above Travel Agents to get the correct cable pull ratio with your integrated shift/brake lever set-up. It is what most manufactures were using before the disc option became the standard. We have the "V" brakes along with the drag brake and never feel at risk in our very hilly area.

rm -rf

If your brake levers don't bottom out against the bars, then the cable pull sounds okay.

You have cantilevers, not V-brakes, correct? V-brakes need more cable pull than newer shifter brake levers allow, so the levers bottom out. Mini-V brakes have the correct pull. The downside is mini-Vs have very little travel, so the pads need to be very close to the rims, and accurately aligned. It's fussy to set up correctly.

Are the pads pressing against the rims over their whole surface? Take off the front wheel and check the pad's wear patterns. EDIT -- you mentioned: " The pads are hitting squarely and pivots cleaned and lubed." I guess you could check anyway.

I don't think you need to roughen the rims. Factory roughened rims get completely smoothed out from pad wear, anyway.

xlbs

Over years of playing around with cantilevers and road levers of various types, converting to V brakes with travel agents has always proven to be the best way to increase braking power (and modulation too) for us.

I took the time to get out my tape measure on several sets of brakes; the mechanical advantage of most good V brakes is immediately obvious.

Even if your brifters are not approaching the bars, if you are having trouble with full power you really owe it to your stoker (as above) to consider travel agents etc. I've challenged myself to find the most powerful pulling position on my brifters, and it's best with minimal pull where my hand/fingers are at maximum closing power just at the start of the action. Whenever my fingers are close to the bar I know that I have missed the best pulling position because my hand is weaker there.

Recently I have also experimented with setting my right brifter to the front brake that my stronger hand controls the most important brake on the bike.

Finally, caliper brakes are just not as powerful as V brakes with travel agents.

Drum brakes are great for setting some resistance on long descents, but they are a poor third cousin for stopping power.