tfmorris

A friend has an old Panasonic road bike which I'm guessing is a mid-1980s Sport xxx (not sure which exact model). She bent the front caliper in a crash, so needs a new front caliper. The LBS sold her a Tektro 539 dual pivot brake as a replacement, but the geometry of the dual pivot brake doesn't provide enough clearance to the top of the tire. The bike has 27" wheels and she's running a Specialized Armadillo 27" x 1.25" in the front which leaves very little clearance to the top of the fork - perhaps 0.25".

The shop recommended switching to a 700c wheel, but a wheel + tire + tube on top of the $40 brake seems like a huge amount of money to sink into a beater. (This isn't a vintage restoration project).

I'm going to fiddle with it a bit more, but figured I'd solicit opinions on the best approach. Some possibilities which come to mind include

1. Take the shop's advice and switch to 700c wheel + tire + tube
2. Look for a lower profile tire than the Armadillo. It seems pretty tall which I suspect is part of the problem.
3. Look for a single pivot brake instead of the dual pivot replacement on the assumption that the geometry will be a relatively close match to the original

Recommendations? Other ideas? Parts suggestions for 2 or 3?

Any and all advice gratefully received!

Tom

dedhed

I'd return the caliper they sold her and go to one of the Boston area bike coops and find a caliper that works. Bring the old one with you or at least know the brand. Likely you'll find an exact match dirt cheap.
My other issue would be with a shop that sold you something that doesn't work in your application. Please, replace your wheel to fit the part we sold you???

CommonWheels - Home

https://somervillebikekitchen.org/

tfmorris

@dedhed - Thanks very much for the suggestion! She'll, of course, return the part, but I'd never have known about the Somerville Bike Kitchen which is literally blocks from where I work. It took a bit of rummaging through their parts drawer and there was really only one brake that worked, but she got a vintage Modelo Equipe brake and new brake cable fully installed for less than the cost of the previous replacement brake. Cables are $2. Suggested donation for the brake was $5-10. Suggested donation for shop time is $10/hr. My tally would have nominally been $22, but I gave the a good bit more -- still coming in under the price of the replacement brake (uninstalled). Of course, she was lucky to get free labor too. :-)

p.s. Folks at the Somerville Bike Kitchen said that CommonWheels is defunct.

Jon T

27x1.25 is NOT the same as 27x1 1/4. Mathematically it is, but in the cycling world of tires, they are very different, hence the fit problem.
Jon

Andrew R Stewart 

While you are correct WRT tire sizing the Specialized Armadillos were made in an ISO of 630 (27" x either 1/18 or 1 1/4). So it stands to reason that the bike is running 27x1 1/4 tires. Since this bike likely came with the slightly smaller 27x1 1/8 tire no wonder the fit is tight with a larger tire. BTW my Sutherland's Manual doesn't list a 27x1.25. What's it's ISO diameter?

My questions- Did the shop where the brake was bought from actually see the bike before purchase? If so then I hope they confirmed the fit first.

My suggestions- First I would try to straighten the OEM caliper. The typical caliper from Asia of that era have fairly easy to bend AL. I've straightened a lot over the years. Usually just leave it on the bike and work away with an adjustable wrench. Of the many dozens I've fixed a few have cracked right then. I don't remember a customer coming back with a broken caliper after I have aligned it.
Next would be to replace the caliper with one that fits correctly. If that means modern dual pivot offerings are excluded then so be it. Shops that have been around for years and have a service reputation might have a used caliper. The last thing I would do is to change the tire size or the wheel/tire size. Last because this is expensive. Now if the wheels were in poor shape and they would be likely to be replaced soon anyway doing it now isn't wrong. Andy

dedhed

That's why I have one of these now obsolete Park brake benders.

Andrew R Stewart 

Yes, I've used that tool a lot too. But I find a 6" adjustable far more useable. Some calipers have more or less thick arms and an adjustable jaw allows for a better fit. That same adjustable wrench also works on the caliper's arm that extends upward and has the casing stop/barrel adjuster on it. This upper arm is often bent by the fork swinging around and the arm hitting the down tube. Andy

tfmorris

As I mentioned, we've got a solution, but just to follow up on a couple of things:

• The 1.25" thing is my fault. I'm an engineer and in my world 1 1/4" vs 1.25" is purely a notational difference. If 1.25" means 1 1/8" or some other measure in cycling tires, mea culpa. I always thought the critical measure was the 27" (which I know is different than the 700c that I run).
• The bent brake was the Dia-Compe that was the original OEM part. I wouldn't have felt comfortable with the strength of the part after straightening the (cast?) aluminum. She had already snapped a crank (yes, I crank!) by stomping on it (it was cracked halfway through from metal fatigue) so wasn't really keen on introducing additional failure-prone parts.

Like I said above, I was in and out of the Somerville Bike Kitchen in under an hour, including time rummaging through their used parts bin for the perfect brake, grabbing a brand new brake cable from their stock, as well as fitting, centering and adjusting the new (old) brake. The Modelo Equipe matches the Dia-Compe that it replaces in vintage and fit, if not exact appearance.

Thanks for everyone's help!

Tom