Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 12-16-11, 12:06 AM   #1
greaper007
Senior Member
Thread Starter
 
Join Date: Feb 2004
Location: Denver, CO
Bikes:
Posts: 51
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Semi-horizontal dropout for first frame.

First, I'd like to thank all the contributors on this forum. I've lurked on here for awhile and have enjoyed and learned much from all the threads. I've been researching frame building for about a year now and I'm about to get started on my first frame (after the requisite practice brazing of course).

Here's my dilemma, I'd really like to build an English style internal geared commuter for my first frame, but every source I've come across dissuades first time builders from using anything but vertical dropouts. I realize I could go the vertical route and make do with a half link for the chain or eccentric bottom bracket, but I'd love to just use a semi-horizontal dropout and be done with it.

Is there any sort of homemade jig that I could construct that would easily allow this? Or should I just suck it up and make a road bike frame?

Thanks

Scott
greaper007 is offline   Reply With Quote
Old 12-16-11, 12:12 AM   #2
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Bikes:
Posts: 14,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
go with horizontal dropouts. What is the rationale for recommending against it? Seems to me that a first time builder is going to make many mistakes that are going to be more problematic than misaligned drops
unterhausen is offline   Reply With Quote
Old 12-16-11, 12:22 PM   #3
Doug Fattic 
framebuilder
 
Join Date: Dec 2009
Location: Niles, Michigan
Bikes:
Posts: 162
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
You do want to use horizontal and not vertical dropouts when making your first frame. No competent advice would suggest it is better to start with verticals because it is much more difficult to get the chainstays to be exactly the same length so a wheel centers. That is one of the most challenging tasks to get right. I discourage my framebuilding class students from using verticals for that reason. An English style frame that uses a wheel with internal gears is a great place to begin.

There are lots of different philosophies on how to fixture (or not fixture) frame assembly. It is difficult to make an accurate rear triangle without an accurately built fixture. It is possible get it right with just a true wheel and a long straight edge with an adjustable screw. That method requires you to spot braze, check, adjust and fully braze each joint one at a time.
Doug Fattic is offline   Reply With Quote
Old 12-16-11, 05:46 PM   #4
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Bikes:
Posts: 14,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Doug, thanks for your viewpoint. It is amazing how many production bikes are made with dropouts out of alignment. The OP made me wonder if I was missing something for a minute there.
unterhausen is offline   Reply With Quote
Old 12-16-11, 09:19 PM   #5
greaper007
Senior Member
Thread Starter
 
Join Date: Feb 2004
Location: Denver, CO
Bikes:
Posts: 51
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for all the replies. I was basing most of my knowledge on this book.



Which I've found to be a decent reference so far but the author discourages anything but vertical socket style dropouts for the first frame.

Doug, do you have a picture of a rear triangle jig like the one you described? I have an image in my head and just want to see if it's the same as what you're describing.

Thanks
greaper007 is offline   Reply With Quote
Old 12-17-11, 12:52 PM   #6
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Bikes:
Posts: 14,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
I suppose that I should keep quiet about that book, not having read it. But I don't see why anyone that doesn't know how to build would waste any amount of money getting anything other than Paterek.

T-tool (hopefully Herbie Helm doesn't mind)

unterhausen is offline   Reply With Quote
Old 12-19-11, 10:11 AM   #7
rodar y rodar
weirdo
 
Join Date: Jan 2008
Location: Reno, NV
Bikes:
Posts: 1,962
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
^That tool looks like a god idea, but what does it clamp to? I would guess the DT, but it doesn`t appear to have a way of splitting the clamp to get it around any tube that`s already brazed into a closed triangle.
rodar y rodar is offline   Reply With Quote
Old 12-19-11, 10:41 AM   #8
erik c
Senior Member
 
Join Date: Feb 2010
Bikes:
Posts: 114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by unterhausen View Post
I suppose that I should keep quiet about that book, not having read it. But I don't see why anyone that doesn't know how to build would waste any amount of money getting anything other than Paterek.

T-tool (hopefully Herbie Helm doesn't mind)

Your feelings about that book are absolutely correct, or at least they were about the edition I looked at. :2cents:

Quote:
Originally Posted by rodar y rodar View Post
^That tool looks like a god idea, but what does it clamp to? I would guess the DT, but it doesn`t appear to have a way of splitting the clamp to get it around any tube that`s already brazed into a closed triangle.
The Berry T-tool upper "clamp" attaches at the seatpost clamping bolt hole found in most seattube lugs not around a tube itself. Upper clamps in appropriate diameters could be added easily enough but that isn't how it was designed to attach.
erik c is offline   Reply With Quote
Old 12-19-11, 10:47 AM   #9
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Bikes:
Posts: 14,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
looks like Herbie's version is meant to attach to a seat post. This avoids the problem of crooked seat lugs for the most part.

I got a couple of diameters of used seat posts from my LBS. They occasionally come in handy
unterhausen is offline   Reply With Quote
Old 12-19-11, 11:27 AM   #10
tuz
Senior Member
 
Join Date: Dec 2006
Location: Toronto/Montréal
Bikes: Homemade mixte, track, commuter and road, Ryffranck road
Posts: 1,180
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think it attaches to the stub of seat tube that extends passed the lug. I made mine with a hinge just in case.
tuz is offline   Reply With Quote
Old 12-19-11, 11:48 AM   #11
tuz
Senior Member
 
Join Date: Dec 2006
Location: Toronto/Montréal
Bikes: Homemade mixte, track, commuter and road, Ryffranck road
Posts: 1,180
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
To the OP. I think horizontal dropouts would be better. A discrepancy in chainstay length is multiplied by about 2.5 at the end of the rim. I.e. a chainstay shorter by 0.5 mm moves the rim off-centre by 1+ mm. The other thing to worry about is matching the dropout heights, but you can set that right before brazing the seatstays.

Last edited by tuz; 12-19-11 at 01:23 PM. Reason: bad maths
tuz is offline   Reply With Quote
Old 12-19-11, 12:54 PM   #12
Doug Fattic 
framebuilder
 
Join Date: Dec 2009
Location: Niles, Michigan
Bikes:
Posts: 162
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Herbie Helm made that T-tool for use in our framebuilding classes. It was based off of a method that was/is commonly used in England. I got mine from the estate/shop of Johnny Berry a Manchester, England builder in 1975. That is why we call it a Berry T-tool. The top can attach itself to the frame in a couple of ways. The first is that it clamps to the seat tube stub above the seat lug. The second way is that the top piece can be removed and the lower part attaches to the seat lug binder. Its primary purpose is to hold the chain stays at the correct angle to the bb while they are being brazed.

Getting a rear wheel to center exactly requires more precision than any other detail in a frame's construction. This is because small differences in chain stay length are magnified more than 3 times by the ratio of the axle length to rim radius. In other words one mm of difference in CS length becomes 3mm+ that the tire is off center. This is why most classic European framebuilders (from before the 80's) with their simple building tools used horizontal dropouts with screw adjusters. It actually takes a very well made fixture to get that part of the build just right if one is using verticals. Most homemade fixtures can't do it. I've heard of the book Scott references but have never read it and and don't know the author. However if he believes a rookie builder should start with verticals, he must not understand the difficulty they present and I wouldn't trust anything else he writes. Perhaps he is talking about the advantages of a frame with verticals (the wheel won't pull to the side under effort and the clearance between the fender and tire can be constant throughout its radius) without mentioning the problems they present building with them?

It is possible to build a very accurate rear triangle right without a fixture but the trick is that each joint has to be brazed one at a time with checks and correcting adjustments made between each braze. If one doesn't want to be bothered making Herbie's tool, an axle between the dropouts (after they have been brazed to the chainstays) with a wire pulling them into the wheelbase line can be your fixture. A true wheel and a straight edge can check that they are in the right position so the next joint can be spot brazed, rechecked and brazed. All the specifics take several pages of instruction in my framebuilding class manual so a complete explanation of that process is way too much to type here but here but I'll provide a general outline of how to braze chainstays to the bb shell (after the dropouts have been brazed to the chainstays) so one can get the idea.
1. Assemble the chainstays into the bb sockets with your miter matching the inside of the shell and an axle holding the dropouts a couple of mm wider than their final width (I.e. 132 if your internal hub is 130mm wide). Some shrinkage always occurs after brazing.
2. Adjust the T-tool or pull the wire around the axle until the axle nut center is on the wheelbase line. For example lay your frame against your full scale drawing so that the bb and seat tube match positions and tighten your wire (that goes from the axle to the seat binder) so that the axle in the rear dropout also lines up on the wheelbase line.
3.Check that your dropouts are equidistant on the centerline with a Park Frame Alignment Gauge. This is the side to side adjustment. Spot braze the non derailleur side to help hold that position. Check alignment again after spotting.
4. Braze only the non derailleur chain stay.
5. After it has cooled, check again with the Park tool that the dropouts (still being held with an axle) are still equidistant from the frame's centerline. If it isn't, bend it until it is.
6. Take out the axle and slide the derailleur side chain stay in and out until a true wheel exactly centers (there are several ways to do this). Spot braze it to the bottom bracket shell in that position. If it isn't still centered after it has cooled, melt the spot again and tap the chainstay in or out until it does (or take it out and start again). When it is correct:
7. Braze the right chainstay in place. Realign the stays (by bending them) so that the inside of the dropouts are the exact width required and still on the wheels centerline. Check again that a wheel still centers.

After that you can braze on your seatstays to the seat lug and finally braze the seatstays to the dropouts one at a time (using the same techniques as you did with the chainstays) to get them the same length so a wheel centers. It is easier to get seat stays the right length because more joints have been brazed that make the rear triangle more stable to work with.
Doug Fattic is offline   Reply With Quote
Old 12-19-11, 08:03 PM   #13
erik c
Senior Member
 
Join Date: Feb 2010
Bikes:
Posts: 114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by unterhausen View Post
looks like Herbie's version is meant to attach to a seat post. This avoids the problem of crooked seat lugs for the most part.

I got a couple of diameters of used seat posts from my LBS. They occasionally come in handy
A case where being able to actually see the picture is a much better solution than knowing what Doug's original looked like.:rofl: (work doesn't like Flickr)
erik c is offline   Reply With Quote
Old 12-22-11, 11:29 PM   #14
greaper007
Senior Member
Thread Starter
 
Join Date: Feb 2004
Location: Denver, CO
Bikes:
Posts: 51
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for all the replies, I'll take everyone's advice and pony up the $75 for the Paterek manual. I'm glad horizontals are the way to go. That opens up a lot of possibilities for me.
greaper007 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 06:48 PM.