RubeRad

Almost done with my Surly crosscheck build, got the last (and very important!) part in the mail, Tektro CR720 cantis from eBay; but look at the springs:



They need to be 2+2, not 1+3!!

It's midnight on the West Coast, I've already messaged the seller and contacted Tektro and searched the internets for whether I can buy an individual spring -- or even a matched pair. Hopefully I'll hear back tomorrow, but since I can't sleep, I thought I'd turn to BF -- help!

Are these common-enough canti coil springs that I could find some in a bucket at my LUVBS?

If I get really desperate, would I be able to plier a spring into the other orientation? (and it still be usable and of comparable power to its mate)?

Anybody got a spring they can spare to mail to me? I'd gladly send a few bucks

xenologer

I'd wait for the seller to respond
unless he bought a bad batch and was trying to shuffle them off; chances are good that he's either got the other spring; or has another buyer sending him an identical complaint.

no, these springs are specific to this brake arm and aren't common in junk bins (unlike shimano canti springs)

no, you cannot use pliers to bend them- they're springs, they'll just spring back ; a bend sharp enough to be permanent will weaken them



cr720s are pretty weak; unless you're seriously prioritizing mud clearance, get Avid Shortys instead

RubeRad

Hmm thx for advice, even though it's mostly bad news. Yes, my hopes are still set on the seller, see the original image, it sure looks like two of each spring in the picture.



The ad also says new/take-off, so I would be surprised if he has more than one set, but maybe he's dealing with taking these off multiple bikes? Does everybody hate these brakes? I read plenty enough other good things about them, since I have them now I'll give them a run before I ditch them for something else.

RubeRad

Also, I don't understand why there are two long and two short mounting bolts. I got the long ones into my front bosses just fine though, and I expect the short ones to work in the rear some day.

Also, I decided to mount the yoke "backwards", at least compared to how I've seen it in pictures; I'd rather have access to the 11mm nut and phillips screw for adjustment

fietsbob

Another Pyrrhic 'bargain' that a walk into LBS , in person purchase, would have avoided.

good luck

RubeRad

This is true, but at an auction price of $25.50/pr delivered vs. MSRP (? rivendell sells for $52/pr), I'll go half price every time.

Chris Chicago

It would be nice to have a good lbs to visit when I want to make sure I get the right thing but I went to my lbs for straddle cables and they tried to sell me ones that wouldn't work. another lbs sold me the wrong size axle, and I had brought the old one with me to be sure of size.

nhluhr

Was a $25 savings worth the useless product and additional hassle you received?

fuzz2050

That's the first I've heard that claim. Most people I've talked to have said the CR720s are strong and easy to set up, while I've head more than a few complaints about the Shorties, (especially the 4's).

RubeRad

(a) yes, I am a cheapskate, and (b) it is a more fair question to ask, over all of the items I have ever purchased online, is the total savings worth the cumulative hassle from a few problematic cases? For me, absolutely, no question. I realize others have different pain tolerance than me (and more money), so they would judge differently.

(And I do like to support LBS in my own way, I have a favorite used/vintage shop that has very competitive prices for labor and some new parts -- and almost free used parts! -- I try to always go there first)

FWIW, due to my immediate emails to the seller and Tektro, both of them are now sending me a replacement spring -- we'll see which gets here first!

Good on the seller for following through on his sale (he just had multiple sets and grabbed a wrong spring), and good on Tektro for just sending me a spring! I searched high and low, but it appears this is not a part that is individually purchasable; I offered to pay, but Tektro customer support just asked "which spring, what's your address?"

I will be sending one spring back to the seller so he will have a complete set for his next buyer, but eventually I expect to have one surplus spring, which if anybody needs it I will freely pass it on.

RubeRad

I researched online a fair bit, and that was my impression as well, with the caveat that some people didn't like the CR720s until they switched to Koolstop pads, which I will do someday when the original pads wear out. For now, the front brake is installed and working great, I expect good things from the complete system!

Al Criner

CR-720s are fine, the Velo-Orange soft brake pads are a good pad for those also.

Don't flame me about the V-O reference, I use them and like them, along with a V-O bb, stem, seat post. I use them, they do what they are supposed to do quite well IME.

RubeRad

No flames here, thanks for the recommendation. I'll look into it more when the time comes to change pads.

xenologer

the discrepancy probably comes from brake adjustment

cr720s are relatively straightforward to setup, since their wide arm design doesn't really leave much room for variance, thus on average they work for most people

shortys i find are very sensitive to straddle wire angle and are difficult to setup, but once set perefectly they are stronger. To do this though, I throw out the precut link wires they come with and substitute yoke carrier type straddle wires. (this allows a much shallower straddle angle for max mechanical advantage*) Seeing as how most people probably don't do that... it makes sense that there'd be poor reviews

*since the cr720 has wide and low arms, straddle angle is necesaraially high to clear the tire; the shorty's dont have this limitation since the arms angle upwards, thus they can be made stronger (if you substitute the link wire hardware)



see sheldon's page on cantilever brake geometry for more in-depth explanation of wire angle vs mechanical advantage

3alarmer

Reminds me of the joke:

Q:What's the difference between a duck ?
A: One leg's the same as the other isn't..............

RubeRad

Yes, I read SB's stuff, and some other stuff, I can't find the quote again right now, but I noted at one point that the recommendation for wide-profile cantis (which CR720s seem to be) is to basically install the yoke as low as practically possible to still clear the tire and/or fender, so that's what I was going to do -- with the caveat that I am going want easy wheel removal. I expect to install them with the barrel adjusters all the way tight, and need to screw them all the way loose to be able to get the straddle wire quick release out.

tanguy frame

one of his feet is both the same ...
...is how I heard that jole