just installed some dual pivot brakes on old trek. thought i had measured and had enough reach but oddly I cannot get the pads low enough on the drive side of the rim. while the other side seams ok. is this weird or am I doing something wrong...or did I just need to get a set with more reach?

here are a couple pics

Does anything change when you close the quick release?

If not, then you need a caliper with a longer reach.

sadly, no. qr changes nothing

This is common when dual pivot brakes are mounted off center. Loosen the mounting nut to allow it to pivot freely, and use the turn the balancing screw on top until the brake looks more symmetrical. Once both arms have the same reach center the brake, tighten the mounting bolt and fine tune with the balancing screw.

is the balance screw the silver one visible near the top right corner in the 2nd pic above?

if so, and I'm viewing it correctly, it did manage to make the reach symmetrical. unfortunately it adjusts the reach on the side that doesnt need adjusting so i can make them even, but only if both are too high on the rim.

Good news, bad news.

the good is that even is the right adjustment, so now the brake is as designed.

Bad news is that it's too short. You can't grow the brake, so you need one with longer reach.

If you only need 1-2mm more reach, you might get it by using a rat-tail file to lengthen the slot a bit. You can also use a razor knife to shave the tops of the shoes so they don't overhang the top of the rim and wear through the tire. So maybe you can find 3mm but otherwise you're SOL.

at first I thought 2mm would be enough, but looking at it again it could be more. plus I'm not sure I could get more than 1.5mm filing. the reach on back is fine so hopefully I can pick up a front brake somewhere cheap and easy.

thanks for the help

QR position won't matter w/o a cable connected.

It looks like you've tried to use a modern short reach caliper on an older frame designed for the old standard reach (or modern "long" 47-57mm reach) calipers. The good news is your rear caliper will work, and you should find a suitable front easily.

The tread on your tires is interesting. I see they're 27". Can you tell me what they are and what you think of them?

Left side looks OK. Right side is also OK (per picture) because the rubber pad does not touch the tire when you apply the brake. I could see the outline of the rim just above the right brake pad. The pad will definitely clear the tire if you grind about 1mm off the bottom of the right brake arm mounting slot. It's normal for the left side to provide a little more reach than the right.

I prefer to keep my pads high (closer to the tire like your top picture)...no more than 0.5mm from the outermost edge of the rim. Close the quick release lever and take a 3rd picture with the pads firmly clamped to the rim. Focus on the right-side pad, where the pad makes contact with the top of the rim.

I believe they are conti pro tour, but I will double check when I get home. I have not ridden them. this bike is new to me and has been a bit of a tar baby. It shouldnt be long now and I will let you know what I think, though my experience with tires is the opposite of vast.

Furballi, I think it may be the camera angle that makes the rim visible but I will give it a go later and post some pictures.

However, I think in the end it might be moot bc if I get a longer reach front brake, I can move this one to the back and wont have to drill out the bridge to install it. since this saves me from drilling, filing, and acquiring the appropriate file it could be the strategy I take.

Tektro R536 or R538 is good up to 57mm drop. If you're lazy and don't want to file the brake arm, then cut off about 1mm off the top of the rubber pad. You're not going to notice any drop in performance, because the calipers will still be able to lock the front wheel. Zero in on the area around the letter "FORWARD" on the brake shoes when you take the picture. External lighting will help with the contrast.

Maybe a dumb question but why didn`t you look up some vintage Weinmann or DiaCompe brakes designed for a 27in wheel/frame installation instead of trying to adapt a brake intended for a 622 wheel/frame configuration?

700c or 27" is irrelevant. Reach is reach, and is set by the maker based on tire section and/or fender clearance considerations. The only time the wheel size makes a difference is if you change from one to the other in the same fork, in which case the reach will change by 4mm in either direction (shorter going from 700c to 27") If the OP has a 27" wheel he already has the shorter possibility, so it's simply a matter of buying the right brake, modern or vintage.

Don`t disagree with the theory FB, but since almost all modern road brakes are even shorter reach tha what he`s trying to fit, and since reach is obviously the problem, looked to me that the only options were to buy a specialty long reach brake or `retro` reproduction (either of which would be hellishly expensive) or to pick up some vintage brakes from an era that that kind of reach was pretty common. And since those vintage brakes mentioned typically go for $10 to $25 I figured it was a valid question.

Point taken, but brakes have actually gotten better in the last 25 years, and good quality vintage long reach brakes can often cost more than modern brakes. I feel for the OP, since he already paid for brakes and it would be a shame to have to buy anew.

Looking at the photos, I suspect that the existing caliper can me made to work, but if not there's one other solution that I didn't post earlier because it requires more skill and isn't reversible.

If you can't raise the bridge, lower the river

Warning, this requires care, but if done right will solve your problems with a front brake. Since the shoes won't go lower, consider raising the rim. There are two ways to do this.

1- if there's sufficient meat on the dropout (check where QR and axle faces engage) you could file the top of the slot. This requires care because both sides must be done equally to keep the wheel square.

2- if the fork is steel with curved blades, you can change the curvature to bring the tips higher. This is a skill job, and best done with a fork raking fixture (many old builders of steel frames have these), but can be done freehand if you have good hands. If you decide to go this route, find someone qualified to either do it for you, or walk you through it. It's critical that it be done right otherwise the wheel will end up off-plane with bike handling consequences.

Uh, dude, looks like you haven't installed the cable and your brakes are wide open there. Try the same thing with the calipers closed using your hands or a third hand tool.

But if that doesn't make a diff then it looks like you have a long reach frame.

Here is my story
I got the new brakes bc I had read good things about dual pivots and wanted to try them out. But I should have been more careful measuring and purchased some with more reach. I also didnt realize that the frame would not accept recessed bolt brakes until this 30 dollar set I found on ebay arrived. At that point I did a little reading and learned I could make them fit by drilling the fork. Seemed kind of harsh so I decided to go with the dia comps it came with. Then the original fork turned out to have a crack in the steerer tube. I judged it easier to replace the fork than fix it and I hunted for a used fork for about a month unsuccessfully. Decided to go with the black replacement fork most lbs sell new. Then when I hooked up the old diacomps there was a lot of flex and they were giving me problems. It probably was just the shoes but when I asked here I was reminded that I could install the dual pivots by drilling the hole bigger in the fork, so I did. It was then that I discovered this reach issue.

As it stands I have 2 hurdles, this reach issue and the rear brake bridge not accepting the recessed bolt rear brake. So if I rig these current brakes by filing, trimming the pad, or bending the fork, I still have to do some other rigging on the rear. But, if I grab a new front brake with more reach for 20 bucks off ebay, I can move this one to the rear with no big issue (I hope/think). if my thinking is incorrect please let me know.

Excellent idea FB! In fact probably the best solution to date! And we`re only talking a few mm so IMO ist perfectly do-able, just the slot angles have to be well aligned.

All you need to do is to drill out the REAR hole of the brake bridge. Do not drill the front hole. The hex recessed nut will go thru this 5/16" hole. Be sure to use the two half-moon washers to clamp against the brake bridge. I would also add a star washer between the brake assembly and the half-moon washer to keep the brake assembly from rotating. Worst case is that the hex recessed nut is too short. You can buy a longer hex recessed nut and cut to length...about $1.50.

FYI, I have a bike with 0.51" thick brake bridge. I use the same hex recessed nut found on the rear R530. Perfect fit. No rigging. Just drill the 5/16" hole. Wiggle the drill bit a little so that the hex recessed nut will drop thru the rear hole. Position the brake to face the front of the bike.

A safety razor blade will cut thru the rubber pad in 30 seconds. Make a cut from the metal pad holder down toward the braking surface. No need to file the brake arm or mess around with the fork.

Total cost of mod is less than $3.

I see and appreciate what youre saying Furballi and maybe i'm being anal but I think aesthetically to me it might be worth the 20bucks to have the brake on the rear side of the bridge.

Then you'll need to change the brake bolt, or buy another front brake. I prefer the cleaner look of the brake bridge area with the forward-facing rear brake. More exposed paint...almost as clean as a fixie.

interesting. I guess i can put it on and have a gander before the final decision

You can drill the front of the brake bridge. I just did my 87 Trek yesterday. Held the 5/16" drill in a vise grip and had at it by hand. It took about 15 min with some interuptions. Recessed nut dropped right in. Not as fast as with a drill but certainly doable.

Now that's perseverance. I personally prefer to drill from the back to achieve a cleaner look, plus the brake will be closer to the rim for a tad bit more mechanical advantage.

impressive. I'd read about that method but it took me around 25min do do the back of the fork, with a drill. i figured the rear sans drill would be at least an hour affair. does your rear brake bridge have a sort of round block where the bolt goes? looking at mine, i'd have to drill out the length of the recessed nut.