ryanlath

Has anyone used Kaisai Curved Chainstays from Rene Herse? Or have a technical drawing or specs of the curve? I can't find any info on their site and they don't seem to have a way to contact them anymore...

Thanks,
Ryan

unterhausen

I suspect they haven't changed their policy about answering emails.

I thought they used to bend their own, but these look to be factory bent.

What aspect of them are you wondering about? I think they are really only needed for 50mm+ tires, you can clear 44mm with ROR stays.

Doug Fattic 

Ryan, here is a picture of those chain stays and BB shell I used on my wife's bike. The tires are 650B X 42 Rene Herse Baby Shoe Pass tires. I'm not where I can do any measurements.

ryanlath

So, I'm trying for 650Bx47 with 415mm round chainstays. I'm trying to see if anything off-the-shelf will get me there... Or close. I'm probably going to have to go oval... And bend.

Doug Fattic 

I can't imagine any round/oval/round straight chain stays only 415mm long can work with 47mm tires. However I'm going only from instinct so the only way to know for sure is to draw them out if you don't have the materials on hand. Are you using a socketed BB shell or going to fillet braze or tig them to a blank shell?

guy153

I put those numbers into my "CAD" and it doesn't look good. This is assuming CS that are 22.2mm/18mm at the oval part. The green line is at 18mm. But if you use CS with a bend in them there will be oodles of room and probably the Kaisei ones will be OK but idk what they're like.

unterhausen

Sometimes you have to just pay the supplier tax and buy the parts. Although I admit $120 for a bb and stays is a lot if it isn't going to work. OTOH, I think that's a smaller tire than what they are made for. But Jan doesn't believe in short stays.

True temper used to make a bent stay. I have one set, I'm waiting for the right application.

ryanlath

Lugs all around is what I'm going for... Yeah, I've been drawing them out... but without some specs, like the Kaisei chainstays, I'm sort of stuck (the clearances will be tight, if doable). I've also only found two good technical drawings of lugged bottom brackets... the Rene Herse (10deg/22 round) and Spectrum's Pacenti (8deg/22round) that have enough info, e.g. chainstay spacing.

ryanlath

I think a 8deg chainstay with Oval stays with a slight bend would work... but I don't think the bottom bracket exists...

unterhausen

I bend them out all the time. I use a stay to bend the outside of the socket out, then a hammer and a piece of wood to close the gap on the inside. Don't use a lightweight stay or one you really want to use because it gets a little dimpled.
It's a lot easier to do this with an oval socket than a round socket. I have had trouble bending the main part of the shell with a round socket. Probably requires some cutting to get it to work.

unterhausen

Process pics: 1st is where I have bent the socket out. There is a pretty big gap between the socket and stay on the inside. If you are using a typical bench vise with metal jaws, I would use soft jaws. I have a couple of pieces of aluminum with magnets to secure it to my vise for that. If you want to be really cool, you can try to find some copper jaw covers, but they are expensive. Second picture is the tools I use. Hammer and a couple of small pieces of wood. It's probably best to do the actual closing of the socket without the stay in the socket. It's easier to form the socket and the stay might get dimples. Third picture is the finished socket.

ryanlath

Thanks! This is the route I'm going!

Andrew R Stewart 

And Eric's socket manipulations and gap closing is a big reason why I use brass/bronze filler a lot on lugged sockets. I've "adjusted" main frame lugs as much as 6* before and the gaps never really close up unless you do a lot of work (like cutting a dart out of the socket base and filling in with weld or braze then resizing the ID). This is also why I've played with making my own lugs. Andy

unterhausen

I don't think you need to use brass for my technique. It's not obvious, but I have closed up the socket all the way around. It takes some work. Even though they are castings, bb shells are pretty malleable.

I did this example because of someone getting bad answers about doing this on facebook, so I wanted to show it is possible. I actually bent it back a little after, so I didn't finish it fully.

Doug Fattic 

I've modified the oval sockets on a BB shell to fit double bent chain stays. I used a punch I hit with a light hammer to bend them to my will. It wasn't overly difficult. A number of my framebuilding class students have also done this in one of my classes because they were building a randonneuring type of frame using wide tires. Nobody had a hard time doing this. Just work slowly and carefully. Everybody used 56% silver. The only thing is that all of those frames were made with chain stays much longer than 415mm.

A punch is an excellent way to shape sockets to fit tubes. They can be placed exactly where the wall should be modified before the punch is struck with a small hammer. Of course before I starting hitting the socket wall with a punch, I bent them with thin pliers. Clean shorelines are really important to me and one of the steps in getting that result is having the socket walls be touching the tube everywhere. No gaps. The method is not to hit hard a few places but gently many places close together. Anyplace there might be just a small gap gets the punch treatment. The BB shells I'm familiar with bend pretty easily.

Doug Fattic 

Here is a picture of a frame I made for my nephew where I used double bend oval chain stays that required I modify the angles of the CS sockets so they fit the bend of the stays. I used this punch set after rough bending the sockets when thin nosed pliers. I kept tapping the socket wall in a thousand places so there was no gaps between the socket wall and stay when I was finished. I can't imagine building a frame with clean shorelines without using this punch set a lot. The materials I use are never a perfect fit and have to be blacksmithed into submission. My students do this all the time. At 1st it seems like it is impossible to close giant gaps but they keep working at it after I show them how it is done and they get it done. it isn't accomplished with big wallops but rather with consistent taps barely moving the punch each time it is struck as it moves around the socket.

ryanlath

Nice! My wife's a jeweler, so I've got a lot of tools to play with (if she let's me...). Also, if I loose my patience, I'll have her do it!

I've got some BBs and oval chainstays coming in the mail to play with. The ovals look like they're pressed/crimped, too... so perhaps just a little bending...

I can't post pix yet, but my latest mockup is in my profile album and looks promising...

unterhausen

I can't find your album or I would post it here for you

Doug Fattic 

Well, well, well, if your wife is a jeweler, she already has the tools to cut designs out of blank lugs. Carved lugs isn't to everyone's taste (or ability) but I bet if you were making her a frame, she would prefer something distinctive she created rather than just something ordinary. She might be more tolerant of you using the kitchen countertop as an alignment table if she was part of the process.

I've got templates that are twice life size to draw a design. They are reduced down to life size on a xerox machine. The design is cut out with jeweler's saws and files. Foredom or Dremel tools ca speed up some of the process. I can email you the instructions and templates if you/her are interested. Here is some student examples. These are some of the more complicated versions but some like to keep it simple just different than what you can buy. The student that made the Smitten frame (he's from Michigan - get it?) also used the same process to cut out the stainless seat tube badge.

Andrew R Stewart 

Using punches and needle nose pliers are just a couple of the tools to manipulate sockets with. Other methods include grinding (die or Dremel) the inside portion of the socket, 4" and 6" adjustable wrenches, bending bars ( Oasis Custom Cycles | Handmade Bicycles and Custom Wheels ) and in the extreme hack saws and your torch.

I completely agree with Doug and others about the need for a no gap socket edge to tube fit to improve after brazing shore lines. However when bending cast sockets (like most current offerings are) the inner most portion won't bend as it's well supported by the rest of the casting. This is where some grinding can help to allow the tube to exit at the desired angle. Even without removal of this inner material a large angle change often results in a gap inside the joint, where the tube end and the base of the socket are. This is (one reason) why I might use brass/bronze instead of silver. Andy

ryanlath

She's way into it. I'm buying her some blanks. I've also tried to discourage her from looking at other lugs... I'm curious what she does. I did bias her a little by saying: nothing that appears on a playing card! Although, I'll probably get a set of the Sachs...

And obviously, she'll get a bike...

I built those countertops, so, no, we'll keep the bikes in the basement!

Doug Fattic 

Like Andy says, it is often necessary to grind some of the socket to get a better fit. In fact oval chain stays and oval sockets have variances that have to be altered to make them fit together. So the problem can be both shape and angle. And again like Andy says, there can be a gap inside the CS socket. I usually fill this gap with 48% silver heating from the inside. It is a little less runny than 56%. They have always held up long term. It is too difficult for most of my students with limited brazing experience to try and braze a socket with brass right after working with silver. It is difficult for them to make the switch. I've never had any trouble myself filling any resulting gaps with silver.

The Smitten frame is an example of a student using double bend oval chain stays.

Doug Fattic 

I've got detailed instructions on how to design and carve lugs if you want to email me for them. How to do this has always been a passion of mine ever since I got my fairly plain Hetchins in 1969. They are very well tested procedures.

ryanlath

Ok, I tried creating an album called "Drawings" and put it there... Thanks!

unterhausen

et voila