rustmyrtle

My husband as a Masi Special CX. We bought it new a year ago.

The brakes have been giving him grief lately, so I looked at them last night, replaced the brake pads; removed, cleaned, and reinstalled the brake arms; adjusted the cable travel; balanced the arms; and trued the wheel. The rear wheel stops perfectly in the bike stand.

However, it still won't stop when it's being ridden, at least not over an acceptable distance. Any ideas what could be wrong?

Wanderer

Clean the pads, and rims, with rubbing alcohol. Do it until the rag stays clean. Make sure the pads are close enuf to the rims, when relaxed, so they have good purchase when engaged.

If that doesn't work, try Kool Stop Salmon Pads.

cyclist2000

If you are just using the rear brake for stopping, that would be the problem. A rear brake does not have much stopping power in comparison to the front.

Just because the brakes stop the wheel on the repair stand doesn't mean the brakes will work that well with a load on a moving bike. On a stand the brake is stopping a couple of pounds of mass, when on the road the brake is trying to stop 250 pounds of mass (in my case).

What type of brake pads are you now using? Are the pads compatible with the rim surface? I had a similar problem with some brakes and replaced the pads with Kool Stops and now I can feel the rear wheel lift off the ground during hard braking. The old pads were glazed over and hard.

bikeman715

Try rubbing the brake pads with some sandpaper and clean again with alcohol , if this doesn't yes replace the pads.

jsharr

As it is a CX, I assume he is riding cross, so using the rear brake is best here in many instance. If however he is using the bike on the road or on smooth surfaces, I would say he needs to use the front much more.

Here is what the gone but not forgotten Sheldon Browne would have us know about braking technique.

https://www.sheldonbrown.com/brakturn.html

I too will say to invest in better pads. I went from Tektro stock pads to Dura Ace pads and I see much better braking performance with the new pads.

powers2b

When adjusting the brakes, squeeze the handle hard, the brake handle should not travel more than 50% and should never touch the handlebar.
Enjoy

m4ximusprim3

how heavy is your husband? If you don't mind me asking.

DannoXYZ 

Depending up on the course and actual braking-requirements, front-brake in CX is still where majority of braking-power comes from. Trailing the rear is common for adjusting line and steering-aim, but it's really not for slowing down.

rustmyrtle, do a controlled test on flat-level ground. Set up a cone or pencil on the road as a starting point and do several full-effort stops:

1. Some with rear-brake only
2. some with front-brake only
3. some with both front+rear brakes.

Measure the stopping distances. Your hubby will have to practice straightening his arms and pushing his body off the back and resting his belly on the saddle to get the most out of #2 & #3. Notice any trends?

conspiratemus1

Sorry, I couldn't resist, but the title of this thread makes me think of, "The operation was a success but the patient died..."

rustmyrtle

Sorry for the delay in replying.

My husband is about 210lbs. I just replaced the brake pads, and the travel at the lever is perfect, wheel centered and trued, etc.

We haven't tried cleaning the rim yet--we'll give that a go.

5b00

The brakes are Tektro Oryx cantilevers, right? If so, there are a few things to try that will increase the mechanical advantage:

1. Lowering the yoke
2. Rearranging pad mounting spacers to make the brake arms farther apart (put the thick spacers on the inside face of the mount)

Doing either or both of these will have the effect of reducing the amount of brake arm movement for a given amount of movement at the brake lever. Instead you get more power over a shorter travel. This means your brake pads will need to be set closer to the rim, or else your brake levers will bottom out before the pads touch the rim. This adjustment will also make the brake levers feel "mushier", instead of the crisp feel you get with low mechanical advantage. Don't worry though, because the mushiness actually reflects the greater power as you squash the pads against the rim.

I have the same brakes, and applying these leverage changes resulted in at least as much improvement in braking ability as changing from the stock pads to Kool Stop Salmon pads. I see that you've already changed pads, but any others struggling with cantilever power might want to try changing their leverage before shelling out for new pads. I must say, though, that the grippy material in the Kool Stop pad can let you get away with a sub-optimal brake setup.

Source: Sheldon's article on cantilever brake adjustment

5b00

Oops, one more thing I forgot to mention. Don't worry about toeing-in unless you really do have problems with chatter. Putting all of the pad against the rim at once seems to result in better braking power than putting it on in stages, as would happen when the pads are toed-in.

TurbineBlade

Bingo, my guess is you have cantilever brakes and probably too low mechanical advantage. This is remedied by lowering the straddle yoke (if it's a link wire you really can't) and making sure the brake pads are extended fairly far toward the rims when the brakes are at rest.

This is done either by clamping each pad post further (on the old style pads) or putting the bigger spacers on the inside of the brake arms (newer style, like tektro oryx, etc.). This gives more leverage.

DannoXYZ 

Yeah, I prefer to have the yoke cable about 1/2" off the top of the tyre. Much closer than this picture:

He was actually talking about reducing braking power by raising the yoke, but we want to lower it.

There was a post about a year ago where someone put up equations to analyze leverage based upon various variables of angle of yoke and angle of the cable-attachments relative to pivot. Can't find it now, anyone have a link?