SvenSurly

Apologies for the all-caps. It's just the angle of this toe-in only conjures up one thing: the image of Macho Man Randy Savage yelling "extreeeeeeeeme" while eating jerky.

Up front, the question is this: is the amount of toe-in I'm about to describe normal in anyone's opinion, or is there any reason why you would want to toe the brakes so aggressively? The bike is a Surly Cross Check, and the brakes are Tektro Oryx with threaded posts (the ones that are adjustable in all directions, not the Shimano-style ones). Levers are Tiagra brifters. The root cause of this whole deal was that the Kool Stop Thinline pads with the regular compound that I recently installed wouldn't stop shrieking under braking, no matter what I did to adjust them.

Anyway, so my LBS sucks. On the recommendation of a friend, I decided to try another shop about a 15 mi ride away. I figured I'd get my exercise and then, hopefully, deal with the horrible shriek from my brakes.

So I get to the shop, and it seems really legit: folks seem to know what they're talking about, the wrenches are battle-scarred and greasy, etc. I hand the bike over to one of them, explain the issue, and watch him re-toe the brake pads. I take it out for a test-ride, and everything works great--no shriek, no noise, and the bike stops great.

But then I get back into the shop, and I see the pads are at this ridiculous angle to the rim--like maybe 6 or 8 degrees. In fact, the angle is so extreme that even under the heaviest possible braking pressure, the rear 2/3 of the pad makes no contact whatsoever with the rim! (See the pics: one with no pressure, and one during light braking.)

I had always heard you're supposed to have about a business-card's worth of clearance between the rear of the pad and the rim when you first apply the brakes. But this mechanic is one that my friend, who knows her stuff, recommended by name; he's a custom frame-builder, has loads of experience, etc. That plus the fact that I've been looking for a shop for some time, and this was the first shop where people talked to me like a human being of some worth, even though my bike isn't the most expensive, high-tech machine out there, made me not want to second-guess the guy.

So again, has anyone ever seen or heard about this degree of toe-in? I really, really want to trust this mechanic and his non-jerky, laid-back-but-legit-seeming shop, but if it turns out that the man can't do a simple brake alignment, should I bother giving him something more complex next time around? My instinct is to trust this guy and his work, so I suppose a secondary question would be, why on earth would you only want 1/3 of the pad touching the rim, even under the heaviest of braking?

Just FYI, I was able to control speed and stop with no issues at all on my ride home.

Thanks, all. Happy Thanksgiving!

reptilezs

it doesn't squeak anymore right? you can also do a toe out, yea it works

dsbrantjr

Your headset-mounted brake cable hanger is likely the root cause of the shudder. I use Specialized fork crown mounted cable hangers and never have any problems.

Google "cantilever brake shudder" and "fork mounted cable hangers" for tons of discussions regarding this issue.

SvenSurly

Nope, the squeak is gone. But I'm just wondering what the other 2/3 of the pad is for if I can stop the bike with the first third. Oh well.

Andrew R Stewart 

Having used Mathouser pads since the 1970s I have a lot of experience with pad squeal. I like to run my pads as flat as possible to get the greatest contact/grip. I've also mounted hundreds of the KS Thinline pads on repair bikes over the last 15, or so, years. The first thing i do, with Thinlines, is to grind off the wegde/scraper bit on the pads leading end. In fact i will slightly bevel this end of the pad to create a small bit ot toe in at the leading edge. I install the pads with a slight toe in, maybe a dime's thickness amount. If there's squeal on the after service test ride i bevel each og the pad's segments, like I did the leading edge, creating a few mini toe ins for each section. The next step is to clean off the rims and pads with a REALLY good solvent that leaves no residue, like Clean streak. If squeal persists I'll toe out. I'll look for a puddle, wet grass, leaves on the ground and ride through/coat the rims/trap between the rims and pads the vegitation. I've even used mulch bark and mud for this.

It would seem counter intutive that a dirty pad/rim will run quiet but that's what actually happens in real life. Any cleaning done at home or the shop will only last for a short time. The rims are very close to the road which is quite dirty. Since this is not what customers expect (and will think that I am BSing them into my not cleaning their bike) I will do the cleaning thing, but will turn away from this sooner then not. Any cleaning done should be with a solvent that won't leave a skim of stuff behind. Most soaps, most all cleaners/waxes do leave a residue. Sometimes i'll do a multy step cleaning with a soap like wash first then a alcohol or Clean Streak to finish up. Don't forget to lightly sand the pads if you run then with a skuzzy rim. But again the cleaning can make the squeal worse. At the shop and in the end if nothing else works I use a different brand of pads. Andy

SvenSurly

Not so sure about that: this is the second or third set of pads I've used on this bike, and the first time I've ever noticed an issue. I'm guessing it's pad-related.

But the real question is whether this mechanic is a genius or a quack.

coupster

Other than the fact that mine are DiaCompe's that looks a pic of my touring bike. For what ever reason, you want quiet brakes, toe until you get it. The rotation of the wheel will drag the rest of the brake pad into contact with the rim, but front will wear more than the rear. Be thankful you've got the adjustment technology; try doing it with smooth posts and pinch bolts.

HillRider

Well, you say the brakes don't squeal any more and the bike stops fine so apparently your mechanic did the right thing.

dsbrandtjr's comment about the long run of bare cable causing vibration and squealing can be correct but is probably not the cause here. That "problem" is pretty much is limited to large frames with carbon steerer tubes where the bending and flexing of the steerer under brake loads causes erratic braking. It was first reported on cyclocross bikes as carbon steerers got to be common. Your Surly's steel steerer isn't as prone to this.

I have a Cross Check that also had a terrible squeal problem, first with Shimano Canti's and then with Avid SD7 V-brakes using both the OEM pads and KS Salmons. What finally cured it was substituting road brake pad holders and pads for the longer "MTB" style pads and holders. The shorter road pads must be stiffer and they do run quietly. Brake performance did not suffer.

DaveSSS 

Since brake pad toe-in is so easy to change, why not experiment with a much smaller amount and see how that works. Learn to work on your bike, so you don't need the LBS.

Shimagnolo

I disagree. My all-steel Soma Double Cross was shuddering, and locking the front wheel, until I got rid of the stem-mounted cable stop and went to a fork-crown-mounted cable stop.

HillRider

1-1/8" steel steerer? BIG frame? Hmmm, that's unusual. Anyway, shuddering and erratic braking have a dfferent cause than squeal and you implemented the cure for your problem. For my Cross Check the squeal continued even after the change to V-brakes which totally eliminated the long cable run beween the cable stop and the straddle cable on the cantis.

fietsbob

Kool Stop's 'Eagle Claw' pads have a rear [leading edge of rotation] tip It seems to help clean off the rim
and when installed New provide just the right amount of Toe in on the trailing edge contact of the whole pad.

Shimagnolo

Before and after photos. Note the length of the headtube. I only removed about 1cm from the steerer when I cut it to fit.

HillRider

OK, BIG frame! My Cross Check is a 56cm so the expanse of brake cable wasn't nearly as long.

jyl

That is not an extreme amount of toe in. Looks fine.

When you set toe-in, you don't start with a business card as shim under the brake pad's leading edge ("leading" is toward the rear of the bike, since that is the end of the pad that "leads" as the pad sweeps the rim). You start with a dime or a quarter. Long pads like that require a thicker shim.

If the brake stops you effectively and without squealing, then it is working.

You cannot stay that 2/3 of the pad does not contact the rim under "the heaviest possible braking", because you have not looked at it under the heaviest possible braking. You have looked at it while squeezing the brake lever hard on a stationary bike. Applying brakes on a stationary bike does not cause the brake arms to twist from the braking force. If you get the bike up to 20+ mph, bend down with your head under the handlebar so you can look very closely at the brake pads, and then slam on a big handful of brake to just short of locking up the front tire or flipping over, then you are looking at it under the heaviest possible braking . . . :-)

Now, suppose the toe in really is too much. Then under heavy braking, the brake arms will not twist enough to lay the brake pad flat on the rim. In a fairly short time (weeks), the trailing half of the pad (toward the front of the bike) will wear down faster, and the braking surface of the pad will become angled until the pad does lay flat under heavy braking. Think of using a pencil eraser while holding the pencil at an angle. In effect the toe in will self correct.

SJX426 

The new LBS mechanic fixed what was broke and knew how to do it. I think you answered your own quesitons. Sometimes we put limitations that do not appear to be reasonable. It is a self imposed limitations. What counts is that it works and well. If you want to understand why, then take some engineering courses and execute a DOE (design of experiment) and realize it only applies to the subject of the experiment.

Burton

Agree - no way you'll see brake post twist just by pulling the brakes. Its the rotation of thecwheel that causes it. Guess I was expecting something more EXTREME from your title.

And some things aren't always intuative. Brand new bikes often have a problem with brake squeal because ..... the rims are squeaky clean. The owner at one shop had a little trick he used when customers complained about that issue - he'd rub a candle around the rim. Personally I thought he was nuts - thats gotta make things slippery -right? Nope - he insisted I test drive the bike and it didn't affect braking a bit - just killed the squeal. And as the rim and pads pick up road dirt - that probably has the same effect .

Anyway - your shop is probably OK. Any mechanic with battles scars and grease on them obviously does more than assemble new bikes - and he was recommended.

gyozadude

I have had issues with similar brake shoe compounds from Tektro on both V-brake and cantis and it's primarily with the front fork and some combination of rim wall finishes. Not every rim type will set off the squeal. And for me, it was primarily the front only. It always looked like the wheel rotational direction will cause inward push on the brake posts on the rear with primary touch point near where the seat stays are, providing better rigidity against vibrations. On the front fork, however, the primary contact is fore of the posts and the stress is more cantilevered. So you'll get unconstrained vibrations if you can hit a harmonic, and oh that sound was great joy, NOT!

I had to toe-in the stock black pads considerably to avoid any grabbing on a welded/pinned seam joint that will set off the micro-vibrations. And even if I did extreme toe-in now, I was likely to get some vibration once the pads wore and if the rim surface wasn't ever worn into a grooved state that probably changed the nature of the pad to rim surface contact. At least that's what I thought did plague me for a while.

My solution was experimenting with various brake pads. The Koolstop half-n-half pink/salmon and black compound shoes ended up being the most quiet, so they're up front and it wasn't a perfect solution. I then had to ride through a mud-pit, squeezing the front brake until the grit wore many small grooves into the front did the final trick to keep it all permanently quiet.

Hope that helps. YMMV.

peterw_diy

I agree that the toe-in seems OK.

But as for self-correction, you've got that half wrong -- the surface will tend to wear until the pad lays flat under their typical usage. The front of the pads may in fact wear more quickly, especially if the rider tends to brake gently. The effect of such uneven wear is to reduce the toe-in, so the brakes will start squealing again, first under heavy braking, then with more routine braking, etc. If/when that happens, it'll be time to toe them in again.

+1 on the notion of learning to do this yourself. As coupster notes, those Tektros are far easier to adjust than the old smooth post cantis of years past. The main concerns are 1) adjusting the pads to strike safely and 2) watching the wear line. If the front of the pads wears more quickly than the rear, you'll need to replace them when the front gets thin even if the rear is still nice and thick. C'est la vie.

GV27

I've had to adjust brakes like that before. It's fine.

As mentioned, seems like you found a good guy. Fixed your problem and made you feel good about the transaction at the same time. Really all you can ask.

jyl

If the pads are initially toed in too much (angle too large, only part of the pad contacts rim while braking), they will wear until they are toed in just right (angle smaller, entire pad contacts rim while braking). Eventually they may wear until they are toed in not enough (squeals).