jefnvk

I need to replace the rear canti brake on my MTB. Right now it is the Altus CT90, that had issues with the plastic collar cracking, it is finally cracking after 20 years. The market for inexpensive cantis seems to be very limited, so I'm down to these two. I replaced the front with a CT91 a few years back, when it broke and I was less knowledgeable about upgrading. The new one works as well as it ever did, mostly just meh though.

Is there any advantage to going to the CR720 over the CT91? I'd replace front and back if I went Tektro, otherwise I'd just swap out the rear with the CT91 and call it a day. Regardless of which I go with, they will be matched up with new Kool Stops. Never used a set of the wide cantis, dunno if they are any better or not.

Andrew R Stewart 

The two cantis are rather different in geometry as you can see. The Shimanos will have a narrower window of adjustment range, especially if the link wire is used. They will also need a smooth shaft pad and some find this harder to set up. Their lesser profile can make a difference with rear loads on a rack. The Tektros have greater straddle cable length choice. Use a threaded with orbital washer mount. They stick out more.


Given the range of set up geometry either brake will be nice or suck. I generally suggest to stay with what has worked for, how long, oh 20 years.


But I have dealt with many hundreds of the Shimanos and prefer the geometry of the Tektros. Andy.

wschruba

The CR720s are fine brakes, but like using the CT91s with the link wire, you are missing a degree of adjustment (being able to slide the pads towards the rim). In practice, it's not a problem, but you should at least be aware of it.

IMO, the least expensive cantilevers for someone who likes to tinker are CT91s with a separate straddle cable/carrier. I've found no lack of power with them, if they are setup with a link wire and the pads set to strike the rim when the arms are parallel with the braking track. As mentioned, using a separate straddle cable provides another degree of adjustability.

jefnvk

OK, by separate straddle cable, you mean skipping the link that came with the Shimanos, running a wire between the two, and connecting it to a carrier?

That was my next question anyhow, if I stayed with the Shimano, if the link or a homemade straddle was better.

wschruba

The link wire solves some theoretical problems (straddle cable wear, system "stiffness"), and some real ones (main cable breakage, ease of setup).

A properly set up straddle works fine, though. The type with set screws to keep the transverse cable from wandering are good, the roller type (for brakes with adjustable springs) are good as well, but even the old Dia-Compe style ones work fine, when you pay attention to the setup of the brake.

You have to weigh the benefits of using a straddle carrier versus a link wire. The "right" link wire provides a good amount of power vs. modulation, but if you want that little bit of extra control, a straddle carrier is necessary.

Andrew R Stewart 

I'll add to this thread that some of Shimano's designs are to facilitate assembly and consistent results, not always the best performance. Their link wires (and remember those plastic set up block guides?) are to minimize the variables. I agree that the CT91s are a very good bang for the low cost. Just not what I use on my personal bikes. Andy.

bradtx

Jefnvk, My touring bikes have brakes similar to your C90/91 brake. One has the original Shimano link wire while the other uses a Diacomp straddle cable and hanger. The latter works just a little better because I was able to set the brake arm to cable angle better. The bike with the link wire would be just as good if I substituted it for the next size longer link wire.

Brad

dsbrantjr

My default cantilever brake setup is CR720s with a straddle cable and Problem Solvers Wide cable carriers. Good clearance for fenders and basically infinite adjustability. You do need to provide a means to catch the straddle cable from fouling the tire and locking it up if the main brake wire parts (if you do not have a fender) but that can be as simple as a reflector bracket under it.

jefnvk

OK, thanks all for the advice. I'm sticking with the CR91, and as carriers are cheap enough I'll give the straddle cable a try. Worst case, I have the link arms to go on anyhow. I'm assuming brake cable works just fine for making the straddle cable? I always have saved my tag ends, I've got a bunch of 1-2 foot MTB ended ones lying around.

@dsbrantjr - Yeah, I still have reflector brackets on.

Andrew R Stewart 

Yes, although you loose the little tab on the cable end which makes grabbing the cable end easier. Andy.

bradtx

This may help: https://www.google.com/webhp?sourcei...raddle%20cable

Brad

jefnvk

Yep, it does, there is a big order going to Niagara for this bike anyhow, might as well toss on the right parts for the job considering the package costs only slightly more than the carriers!