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-   -   Canti brake issues (https://www.bikeforums.net/cyclocross-gravelbiking-recreational/610477-canti-brake-issues.html)

moralleper 12-22-09 12:32 PM

Canti brake issues
 
On my wife's bike, 2009 JTS, the brakes are setup motocross style, reversed with cross top levers. The left hand rear brake is pretty hard to pull and does not seem to have much leverage for stopping. I have changed the pads, cable, and housing. I have also pulled off the brakes and clean and greased the post. The lever it self seems fine as it move fine when the brake is not attached. The action on return seems slow and the cross top lever moves when you squeeze the sti lever. If anybody has some ideas on what else to check please let me know, my next step is to replace the brake. The brakes are a dia-compe with no number on them so I cannot give you the model. the sti levers are DA 7800.

thanks in advance,

flargle 12-22-09 01:45 PM

I'd be curious to see a photo of the brakes.

If the crosstop lever moves when you squeeze the STI, it probably means the crosstops aren't completely returned to their open position. Some models have a reach adjustment, you might want to mess with that. Also maybe the housing between the STI and crosstop has some slack, that would make the braking mushy. It should be strongly wedged into the stops on both sides and pushing into the bars in between.

Might want to mess with the straddle cable, probably shorten it. This will change how much mechanical advantage the brake has.

Fun reading:
http://www.sheldonbrown.com/canti-trad.html

moralleper 12-22-09 08:00 PM

There is no reach adjustment on the levers. here are some pics.

http://i36.photobucket.com/albums/e3...is/brake-1.jpg

http://i36.photobucket.com/albums/e3...e_routing1.jpg

Andy_K 12-22-09 08:22 PM

I'd definitely lower the yoke on the rear brake and shorten the straddle cable accordingly.

It also looks like the cable turns up at the seat post. Shortening the cable housing there might help.

Should I ask how you ended up with Dura-Ace brifters paired with those brakes?

moralleper 12-22-09 08:43 PM

we bought the bike used and that is what it was setup with. I to thought that was a bit odd. I will give that a try thanks, here is a pic of the rear

http://i36.photobucket.com/albums/e3...e_routing2.jpg

pacificaslim 12-22-09 08:50 PM


Originally Posted by moralleper (Post 10177474)
The action on return seems slow and the cross top lever moves when you squeeze the sti lever. ,

This should not happen. When you pull the sti lever, the cable should simply move right through the cross top lever. If you pull the cross top lever and hold it, when you pull the sti lever it should force the cross top lever to return to normal position.

I'd check the installation of the cross top levers. If you post one more picture showing the cable run from the sti lever to the cross top, maybe we'd see something that's not quite right.

Also, I think you need to shorten those cable housings quite a bit so they are just a smooth arc from the cross top lever to the next housing stop.

moralleper 12-22-09 10:03 PM

Okay so I have now shorten the front housing by 2-3 inches and the seat tube house by half an inch. I also lowered the straddle cable down. This all helped the slow return and the crosstop lever moving when using the STI lever. I still have little or now power though which seems strange.

wesmamyke 12-23-09 03:16 AM

It can be pretty tricky to get it perfect. It's hard to tell from the pictures how the spacers are setup. Try putting the larger brake pad spacer inside if it's not already.

It can a problem with the housing under the bartape. Check to see if the ends of the housing are seated into both levers fully and really open up and de-bur the housing.

The other thing that can make a huge difference is how much tape you did or didn't use to hold the housing to the bar. Use tons of it....a good test is to pull the brake lever while holding the other hand tight around the bend of that same side of the bar. Can you feel the housing flex or creep when you do this? If so it probably needs to be held down better.

Post pictures of the secondary levers and the new position of the straddle cable if you can.

meanwhile 12-23-09 05:07 AM


Originally Posted by Andy_K (Post 10179404)
I'd definitely lower the yoke on the rear brake and shorten the straddle cable accordingly.

Yes, read the Sheldon Brown link above.


It also looks like the cable turns up at the seat post. Shortening the cable housing there might help.
There's no "might" about it! I wondered if there was a path problem when you mentioned the poor return. Again read the appropriate SB article.

Given the odd mixture of components on that bike I might change the brake pads as well - Kool Stop Salmons if the bike will be ridden in the wet.

Andy_K 12-23-09 10:45 AM

Here's another good Sheldon Brown link:

http://www.sheldonbrown.com/cables.html#routing

Also, someone above mentioned brake pad spacing. A really good tip someone here gave me was to set it up so that the brake arms are parallel to the rim when the pads make contact. That may be mentioned on the Sheldon Brown site too.

And speaking of the Sheldon Brown brake adjustment article, I know first hand that it can be really hard to get your brain wrapped around what he's saying, but it's definitely worth the effort. I probably went through half a dozen cycles of reading it, trying to adjust my brakes according to what I thought he was saying, not being happy with the results and going back to re-read the article.

moralleper 12-23-09 10:51 AM

last night I shortened the straddle cable so the when pulled the angle stayed at 90 degrees or more. The helped quite a bit but still was a little weak. This morning I switched the CVS washers around so the large washer is on the inside and I think that all the changes might have resolved the issue. I will test this out when the temp goes above freezing today since our road is covered in frozen fog, got to love winter in the PNW.

meanwhile 12-23-09 02:23 PM


Originally Posted by Andy_K (Post 10181175)
Here's another good Sheldon Brown link:

http://www.sheldonbrown.com/cables.html#routing

Also, someone above mentioned brake pad spacing. A really good tip someone here gave me was to set it up so that the brake arms are parallel to the rim when the pads make contact. That may be mentioned on the Sheldon Brown site too.

And speaking of the Sheldon Brown brake adjustment article, I know first hand that it can be really hard to get your brain wrapped around what he's saying, but it's definitely worth the effort. I probably went through half a dozen cycles of reading it, trying to adjust my brakes according to what I thought he was saying, not being happy with the results and going back to re-read the article.

There's a Keith Bontrager article that's much easier to follow. I've given the link here before, it should be an easy search.

gfactor 12-31-09 02:05 PM

What I got from the Sheldown brown article is that it is all about your yoke angle and you are trading off mechanical advantage vs. travel by adjusting the yoke angle. Lowering your yoke will increase the mechanical advantage but allow less clearance.


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