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how long should the main-spine be? Note: Tanner W uses the longest piehe could find

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how long should the main-spine be? Note: Tanner W uses the longest piehe could find

Old 03-22-21, 09:11 AM
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apollodriver
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main-spine how long? 2000 mm - longest piece, we could find?

good day dear community.


i am currently creating my own bike-frame-jig. - according the plans of Tanner W


the question is: how long should the main-spine be? Note: Tanner W uses the longest that he could find came in a 1220 length



question; should i go up to 2000 mm or is it enough if i choose any smaller size? look forward to hear from you


see the quotes for more infos:


https://www.instructables.com/Bicycl...-Building-Jig/

see what tanner writes
As I mentioned in the introduction, I wanted to keep the main spine long enough for long chain stays. The longer the main spine the longer chain stays you can make.The length of the main spine is very roughly the max chain stay length plus the max effective top tube length you want to make. (this simple approximation does not account for BB drop, HT and ST angle or the width of the vertical spine piece but it is adequate). A size large Surly Big Dummy has chain stays that are 827mm long and an effective top tube length of 614mm. With my simple formula that gives a spine length of 1441mm. The longest pre-cut piece of 80 - 160 extrusion that I could find came in a 1220 length. I bought this piece and left it uncut. The vertical spine is made of 80 - 80 extrusion. It needs to be long enough to allow the head tube to be held at various heights. Head tube height is not a primary measurement from frame design. However, with the Arctos design it is used to set up the jig for a particular frame.

I decided on 700mm for the vertical spine. This should allow me to build bikes as large as I will need to. Because head tube height is a measurement used for setting up the jig, I wanted to inlay a measuring device. I ordered adhesive backed metric measuring tape from McMaster Carr. I used the Bridgeport mill to mill a grove of the same width as the tape up the majority of the vertical spine. Alignment of this tape is based on the Head tube assembly, I will discuss it further in that section.

see some ressources with image - Here we might get some frehs ideas

Kristofer Henry https://www.flickr.com/photos/blackc...7623797632479/
note: Kristover surely has got 2000 mm - what do you think?

https://www.pinterest.dk/pin/788270740998752173/


https://www.flickr.com/photos/kolb-r...u/50397572342/


https://www.flickr.com/photos/kolb-r...u/50188855773/


https://www.instructables.com/Bicycl...-Building-Jig/


https://www.instructables.com/Bicycl...g/#The%20Spine


https://amhoov.org/2019/08/06/bicycl...lding-the-jig/


see all the links - well i lookward to hear from you


see the thin spine

https://www.mtbr.com/threads/80-20-f...thread.991932/

besonders https://www.mtbr.com/threads/80-20-f.../post-12255152

https://www.mtbr.com/threads/80-20-f...991932&slide=0


question; should i go up to 2000 mm with the lenght for the main spine: or is it enough if i choose any smaller size? look forward to hear from you


look forward to hear from you

regards

Last edited by apollodriver; 03-24-21 at 10:41 AM.
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Old 03-22-21, 10:35 AM
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Go as long as you can. It's not just CS length you have to worry about. If you ever make a "long low slack" MTB even in a medium-ish size you can end up with a DT 750mm long (as opposed to about 620mm for a road frame for a similar-sized person).
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Old 03-22-21, 06:46 PM
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I agree that longer keeps future options open. And that's a good guiding principle. Open options. Andy
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Old 03-23-21, 03:11 AM
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dear Andrew - dear guy,

many many thanks for the quick reply and for all your hints. I will do accordingly.

Originally Posted by Andrew R Stewart View Post
I agree that longer keeps future options open. And that's a good guiding principle. Open options. Andy

many thanks - have a great day

regards
apollo
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Old 03-24-21, 12:12 AM
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I don't disagree with the idea of going as long as you can but generally with the long slack geometry, the rear end is quite short. I haven't done anything that didn't comfortably fit on 1220mm long beam. Doing some rough calculations, the wheelbase would need to be upwards of 1300mm before 1220 wouldn't be enough. The front of the beam sits roughly inline with the HT bottom edge, not the axle. I know another 5-6inches of length on my beam would be annoying to as it would make it that much harder to get around it in the shop.

Here's an example of a long slack and if you're building a fixture based on the Arctos design, some of the front center is excluded. I'm not saying the below is perfectly measured out but by my calcs, even the below would fit on a 1220 with 200mm (8in) of extra length.

Anyway, if you have the room, why not have the extra length - you can add hangers for common fixture tools and what have you. I don't think you'll be limited by going with 1220 or even 1000mm and that saves a fair bit of shop space. Post up pictures as you go!
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Old 03-24-21, 02:50 AM
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The one I made had a longer CS (450) but a shorter front-centre (776). Total wheelbase 1218. So not far off your limit! You're right people often do go with a short CS. I think that's why the design you've shown has a curved ST. With mine there isn't that much rear tyre clearance even with a 450CS:
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Old 03-24-21, 10:39 AM
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hello dear Guy hello dear duanedr

many thanks for your new replies and for all your ideas and thoughts that you share here.

Well - the (shop-) space here is not too much - so there are quite some general limits - but as you force me to go up to 2000 mm i will do so

at the moment i am in the mid of planning stages .. i keep you posted


look forward to hear form you again
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Old 03-24-21, 06:46 PM
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Originally Posted by guy153 View Post
The one I made had a longer CS (450) but a shorter front-centre (776). Total wheelbase 1218. So not far off your limit! You're right people often do go with a short CS. I think that's why the design you've shown has a curved ST. With mine there isn't that much rear tyre clearance even with a 450CS:
You are including the triangle under the headtube and forward to the front axle. That wouldn't be within the fixture length. This probably frees up 200mm or so...I don't think anyone would ever build a standard single that wouldn't fit on a 1220 beam. As I mention, if you start doing long tails or something like that, perhaps then it might be an issue .
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Old 03-25-21, 03:00 AM
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hi there - many many thanks for the quick reply and for this fruitful discussion .


i am new to this topic i appreciate every comment - every answer here. This is all very very important to me.


Originally Posted by duanedr View Post
You are including the triangle under the headtube and forward to the front axle. That wouldn't be within the fixture length. This probably frees up 200mm or so...I don't think anyone would ever build a standard single that wouldn't fit on a 1220 beam. As I mention, if you start doing long tails or something like that, perhaps then it might be an issue .
great - well as said above

i really appreciate all your ideas, thoughts and i love this thread.

so you are arguing for using up to 1220 mm beam - or max 1500 but 2000 is quite tooo much !?
this would have some benefits - the shop-space here is not tooo large - in other words - the 1220 beam is quite smaller and would fit into my rooms even more - than the 2000 beam would..


love to hear from you all -- and look forward to the discussion here

greetings from good old Europe
yours Apollodriver


btw: as duanedr mentioned:
Doing some rough calculations, the wheelbase would need to be upwards of 1300mm before 1220 wouldn't be enough. The front of the beam sits roughly inline with the HT bottom edge, not the axle. I know another 5-6inches of length on my beam would be annoying to as it would make it that much harder to get around it in the shop.
But if i get more options with a taller beam (up to 2000 mm) i will go the hard way ...


As allways - i look forward to hear from you


Last edited by apollodriver; 03-25-21 at 09:44 AM.
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Old 03-25-21, 10:18 AM
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Originally Posted by apollodriver View Post

so you are arguing for using up to 1220 mm beam - or max 1500 but 2000 is quite tooo much !?

I can't imagine a single bike that would require more than a 1220. If you've never built a bike before, don't waste your money on a longer beam to start with - many of us would argue that you shouldn't waste your time/money on a fixture at all until you have a few completed bikes under your belt. A new, longer beam will be the smallest tooling $$ outlay you make if you get to that point of making long tails or tandems regularly.

Remember that a fixture is one more part of the process that requires fiddling. adjusting, maintenance and additions for new standards. The more time you spend on that, the less time you spending building bikes and perfecting those skills. The value of that information won't hit you until you're into the craft 5+ years and you have a deadline, 2 machines that need work, your shop is a mess with tooling. half-completed projects and a bunch of crap that your wife/GF/roommate decided didn't belong in the house any longer!

For your fixture, focus on mobility. The ability to rotate it and tilt it are MUCH more useful than 500-800mm of wasted space at the end. My spine is 1220 and if I had a bandsaw that cut straight (one of the machines needing work) or a mill big enough, I would cut off 200 mm to gain more space in the shop.

Have fun and post up progress and pictures!!
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Old 03-25-21, 10:40 AM
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My fixture includes the front axle position, copying the idea directly from Bill Grove who probably didn't come up with the idea himself either. I'm not sure what I would do if I were going to build a tandem. I was thinking about building a long tail utility bike, and I probably would build the rear triangle separately and tack it on without having full fixturing.
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Old 03-25-21, 02:39 PM
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hello dear Unterhausen hello dear duaneder

many thanks for all these ideas & thoughts and your shared experience. I am convinced - that the first steps in creating a jig should not take tooo much "extra"-considerations in extra-extra options

i will go with the short solution - you have convinced me.
(as my shop spaces is limited too a bit ) and my GF (is probably as you described ) dear duaneder.

our wife/GF/roommate decided didn't belong in the house any longer!
so - keeping it short is a wise decision ...(anyway)


many many thanks for all your thoughts -and for this great thread. I love it!
have a great day

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Old 03-25-21, 06:20 PM
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Originally Posted by unterhausen View Post
My fixture includes the front axle position, .
Yes, that's a whole different thing. I should have stated that my primary assumption is the Tanner/Arctos type of fixture where the bottom of the headtube is near even with one of the main spine. Mine actually sites a couple inches in front of one end. There is also an assumption of the arrangement of the rear axle holder and how much of the spine is needed for that.
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