Andy_K 

I recently decided to jump on the 650B bandwagon. I wanted to convert my 1982 Specialized Sequoia and had read accounts of several people doing so successfully, but to my surprise when I put the rear wheel on the bike my Tektro R559 brakes didn't reach the rim. They were close, but not quite there. I fit the wheels on a different bike, but wasn't quite satisfied. I pieced together a ghetto drop bolt for the Sequoia, which worked but didn't leave as much fender clearance as I wanted.

I did like the ride of the 650B wheels on the Sequoia, so I decided to invest in what I thought was a perfect solution: offset brake pad holders from BDop Cycling.



These holders take a standard Shimano-compatible road pad, bolt on to standard caliper brakes and provide an extra 7 mm of reach. I guessed that I only needed about 5 mm more reach, so I was certain this would solve my problem fairly cleanly. The holders arrived yesterday morning, and I was very excited. Last night, I made my way to the garage to install them. Easy-peasy, right?

Actually....



I'm not sure how well you can see it from that picture, but the problem I quickly ran into is that when I squeezed the brakes the top of the holder made contact with the tire. This is with a 38mm tire on a 23mm wide rim. Obviously it would only get worse with a wider tire or a narrow rim.

But I'm a man with power tools and no common sense, so I wasn't going to let a few millimeters of only possibly structurally important aluminum get in the way of completing my project. After all, it was only the rear brake. What's the worst that could happen? A few minutes later, I took this pic to document the modification.



A little more grinding and Bob's your uncle.



Yeah, that looks a lot like the "before" picture, but trust me, even with the brakes fully applied there's a gap between holder and tire. I'll need to keep an eye on it as the pads wear down, but today it works.

I suppose I've now officially doubled down on the goofiness of how these brakes look.





I'm very happy with the bike though.



Anyway, I thought I'd share my experience in case anyone else is considering the BDop brake pad holders. I think they'd be perfect with more traditional road tires (say, 700x28 or so) on a frame where the brakes you wanted to use just didn't quite reach. I think they can be made to work with 650x38 tires (as @gugie says, "We shall see...."). I wouldn't recommend them for use with 42s.

corrado33

So what happens when the brake pads wear down?

Andy_K 

More grinding? I think it'll be OK.

dweenk 

"But I'm a man with power tools and no common sense,"

Say 10 Hail Sheldons and donate something to the co-op.

dweenk 

Oops! Double post.

bikemig 

The Dia Compe 810s would have done the job but they're nowhere near as nice as the Tektros and you wouldn't have had the pleasure of taking out your power tools to make this work, : )

The Dia Compe 750s would have come very close to working.

ironwood

Or, you could have used Weinmann or Dia-Comp 750 centerpulls.

ThermionicScott 

But what's the fun in that?

Seriously, though, I appreciate threads like this since there are times I wonder if my 650B conversion would be nicer to ride with some modern long-reach dual-pivots rather than its Weinmann 750s.

Andy_K 

Yeah, I could have used the super long reach center pulls, and that's still out there as an option. Honestly, I've been looking for an excuse to try the BDop holders for a while now because I've had a number of problems that I thought they might solve. You'll notice I bought two sets even though I only needed one for this project.

My improvised drop bolt also solved the problem and I could probably have refactored it to work with the fenders. @gorillagirl has told me that she made 650B wheels work on her '82 Sequoia by mounting the brake in front of the rear bridge. I just wanted to try something different.

To answer the question that I'm sure someone will eventually wonder about, I didn't notice any difference in braking performance with the offset holders. It's only the rear brake and the reach was already really long, so I guess you need to take that with a grain of salt, but it feels solid.

Andy_K 

The other thing I considered was these beasts that can be found on eBay.



They claim 76.5 mm of reach, but I haven't been able to find any reviews.

nlerner

I bought a set of those for a 650B project and have to say they really are crap. Spongy as all get out, cheaply made, not particularly good stoppers. You get what you pay for with those brakes.

Andy_K 

That's kind of what I was afraid of. Thanks for the feedback!

corrado33

Do you think any of that had to do with the fact that you're trying to brake using a lever that's almost twice as long as originally intended? I'd imagine brake performance drops consistently the further down you put the pads...

nlerner

Sure, I think that's part of the issue, but have Tektro 559 calipers w/ 73mm of reach on one 650B conversion, and they're excellent stoppers. The Alhonga brakes have just 3mm more reach, but a lot less performance!

Andy_K 

Dual pivot calipers are a bit more complicated than that. You can't just compare the reach of two brakes and assume that the mechanical advantage drops off proportionately. A brake like the R559 has a long reach to the pads, but it also has a long lever arm coming from the pivots. The Alhonga brakes don't look obviously worse in this regard, so I'd guess that the problem is that they have more flex.

gugie 

All I can add is that using power tools is always a good thing.

Makes you feel powerful.

A torch, now...

nashvillebill

Other than having the bolts torqued tight, what's to prevent the offset pads from rotating when they are applied?

HTupolev

Hope.

Andy_K 

Andy_K 

I'm not sure I understand the question. Which way do you see them rotating?

nashvillebill

Around the pad mounting bolt. With the original pads, the pads are on the same plane as their mounting bolt, so there's no torque induced about the bolt. But with the pads lower than the mounting bolt, that offset creates a torque--the pad will attempt to twist about the bolt if the bolt is poorly tightened.

HTupolev

nashvillebill

Thanks for drawing what I was attempting to describe.

Andy_K 

OK, I see now. I guess it's just having the bolts torqued tight. I'll report back if I have any problems with that.

RiddleOfSteel

I think, as rear brakes, they will be fine. Just like a car, the fronts do the majority of the work. I have had to do 'proportional braking' (right up there with 'speed dents') on my Raleigh as the short reach Campy brakes at full max will reach in front but run shy about 1.5mm in the rear. Soft rubber, meet bastard file. Chamfering the pads solves the problem...for a long while until they wear down. But hey, less chance of skidding in panic braking = safer right? They stop just fine. Glad you were able to find a solution. Always a bit anxious when staring down the rabbit hole of 'I just gotta make this work--I'm so close!'