Recreational Cyclocross and Gravelbiking - Tektro CR720 problems, brand new out of the box.
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09-17-11, 12:37 PM
Just going to to say up front, that this is on an old bike, an 85 Schwinn Sierra that I am building up as a light offroad and/or touring bike. The mounting posts have no noticeable wear despite the age of the bike, which is in excellent condition. It's probably never been offroad once since new, it's that clean.
Anyway, just got the CR720's in this week and installed them. I tried a baseline setting with the pads set flat against the rims. On the first ride I noticed no real noise except for the front. There was a slight squeal, but not horrible. What did bother me was the shudder I experienced from the front fork. Kind of spooky, glad I wasn't trying my first 30+mph pavement descent!
So, I say what the heck, and toed them in like I would on any canti to stop the howling/squealing. It actually got much worse. Both wheels are making an awful noise now:rolleyes::twitchy:... Sort of a low pitched groan..
I am going to check the headset bearings to hopefully eliminate that as the cause of the front shudder. But? I guess I should go back to the flat adjustment? Change to Koolstops? I am an experienced mechanic and I have never seen toeing brake shoes inward at the front do anything other than quiet down a canti brake. What would/could help this, other than what I am already going to try, or have tried?,,,,BD
09-17-11, 12:43 PM
you will want to run them with a good deal of toe in. i also found that running a long straddle cable helped. if you are used to low profile cantilevers your straddle cable is probably too short.
09-17-11, 12:59 PM
How far above the brake pivot bolts should the straddle be? Is there a good rule of thumb? Or does it go by the length of cable between the ends of the brake arms and the straddle pinch bolts? As it is right now, the main binder for the lever cable(IE: top allen bolt of the straddle) is even with the bottom cup of the headset. The middle of the allen bolt on the straddle is 3.5 inches above the outer edge of the rim. Maybe I should hook up my camera, hehe.,,,,BD
09-17-11, 01:05 PM
your straddle cable is really low. you will want the cable to come off of the brake arm as close to 90 degrees as you can. let me get you a link.
09-17-11, 01:11 PM
here is a picture of my setup. check your pms for further info:
09-17-11, 01:33 PM
I redid the front now, and the angle looks very similar to yours. I also have a LOT of fork clearance. To the tune of 1.5 or slightly more between the tire and the bottom of the fork crown.,,,,BD
09-17-11, 02:10 PM
Make sure you get me a ride report :-)
09-18-11, 07:39 AM
At first I had used a dime for the toe in measurement, and on the second try I used a quarter. That and the lengthened straddle cable seemed to do the trick. They feel a little weaker than before, but then again they were insanely powerful on the first setup. They have a little more modulation now, which is a good thing. I still may get some koolstops in a few weeks. Do they make inserts for these? On second thought I didn't like the threaded posts being loose in the shoes. Who thought was a good idea? It makes the toe in procedure a little vague, and you really have to pay attention during the adjustment. You have to be sure you're moving the whole shoe, and not just the post. All around I am satisfied with them though, and they were a nice value(EP bought:-),,,,BD
09-18-11, 11:24 AM
am i correct in thinking you have the long "v brake" style pads as apposed to the modern road bike pads? (they have sold them both ways)
ive got the v brake style pads and currently have a pair of jagwire red inserts in mine. i wanted koolstops but these were in stock locally and the LBS about gave them away ($4). any shimano style pad insert will fit fine and should be better than the ones in there now. my stock pads were almost worthless the first time they got wet.
09-18-11, 05:45 PM
Maybe this seems odd, but my tektro 710 stop better than my other cross bike with bb7's. The solution to stopping the shudder and squeal was toe out. Different, but maybe worth a shot
09-18-11, 06:01 PM
i may try that. mine are quiet toe in but i still get some shudder depending on the conditions.
09-20-11, 06:48 AM
Yep, they're the long pads. I am having an issue now. I got SKS commuter fenders, and they fit so high off of the tires that it caused a three way pile up. The brake wants to higher like we talked about, but the rack mount is getting in the way. Then the straddle cables seem to want to ride on the edges of the fender as well. I will get it figured out though. I have a strong downward bend in the front rack mount, since the slots in the supports aren't long enough. Some shorter "straps" would do the trick.,,,,BD
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