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Thread: GBB #2 - Squishy
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07-18-2014, 03:23 PM #1Registered User
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GBB #2 - Squishy
Garage Built Bike
The first bike I built didn't collapse or crumble so it's time to start a squishy bike.
Sweeeeet new bike. Some assembly required.
In the pic above you see, bb, head tube, seat tube, down tube, top tube, vertical spars, chain stays, and lastly seat stays. The bb, head tube, and seat tube are all bike specific tubes. The BB is pre-threaded, head tube is 44mm so I can run a tapered fork, and the seat tube is one that Chromag has TrueTemper custom drawn for them. It's 31.6 id so it accepts any dropper post.
Hand drawing for a hand made bike.
No fancy Solidworks or AutoCAD here, just good old fashion pencil and paper. A full scale drawing is done to translate the numbers in my head into a 2d space. One of the most common questions I've had on my first bike is how did I design it, did I copy a set of plans. I kinda assumed that most riders understand bike geometry and dimension, but maybe more don't than I expected. I've been riding since the early 90's and geeking out on that stuff for years so it wasn't a stretch to figure most of it out.
Hacked into rough lengths.
Started the process of cut n file.
Info on the frame
650B
66 HA
75 SA
420mm chainstays
595mm stack
449mm reach
10mm bb drop
155mm of travel
160mm fork (old Fox 36)
...more to come
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07-18-2014, 03:32 PM #2
subscribed...!
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07-18-2014, 03:42 PM #3
Badass!!!
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07-19-2014, 11:22 AM #4
nice, so fun to make exactly what you want (or think you want)
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07-19-2014, 07:57 PM #5
Bonus pts if you incorporate Switch Infinity in the pivot
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07-19-2014, 09:40 PM #6
How many antisquats are your putting in the frame?
Besides the comet that killed the dinosaurs nothing has destroyed a species faster than entitled white people.-ajp
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07-19-2014, 10:50 PM #7spook Guest
i guess if you're into that kind of shit
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07-20-2014, 07:22 AM #8
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07-21-2014, 11:16 AM #9Registered User
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There will be Infinity anti-squats.
Didn't get to work on it over the weekend as I was away.
Fitting timing for Pinkbike to post up a review of the Xprezzo Ad-Hoc. My current bike is an Xprezzo Super-D and I've pulled liberally from the Ad-Hoc in the design of my bike. The reach and stack are lifted directly off their geo.
For the head angle I went to a round 66 instead of 66.6, the front centre will end up a touch longer than their medium but I plan to run a shorter chain stay length. My main pivot location is pretty close to theirs and if I've fiddle just right with the shock I should be able to get it to be pretty linear and will feel similar in the mid-zone of the travel.
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07-21-2014, 12:16 PM #10Registered User
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sounding rad, more intricate details and random design issues stumbled upon are always welcome
whats the end game goal in feel and use?
got a shock in mind you are building based on?
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07-21-2014, 12:29 PM #11spook Guest
make sure and have neighbor's kid ride it first
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07-21-2014, 02:35 PM #12Registered User
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End goal is "enduro" bike. I want it to excel in the steeps at DH speed.
Shock will likely be a Monarch Plus RC3 7.875x2.25. I have a Fox RP3 that might also see time in there and a friends Roco Air TST R to borrow and try.
The main pivot is one of the big design hurdles to over come. I'll be using a 44mm head tube as the main pivot housing. Two upper cups from a headset will be the bearings, then a steer tube as the pivot axle. Rear swing arm will then bolt onto the pivot axle. This means that it won't need any special machining. Standard bike shop tools to get it done.
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07-21-2014, 04:10 PM #13
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07-21-2014, 04:25 PM #14Registered User
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http://www.henryjames.com/
http://www.cycle-frames.com/bicycle-frame-tubing/
http://www.aircraftspruce.com/catalo...tubing_un1.php
http://www.paragonmachineworks.com/
Those four links hold anything and everything you need for materials.
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07-21-2014, 05:50 PM #15
Super cool. Put some sliding dropouts on it ;-)
Waste your time, read my crap, at:
One Gear, Two Planks
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07-30-2014, 03:35 PM #16Registered User
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Progress is a bit slower than I'd like but it's moving along. Front triangle is mitred out. The little templates save some time, but still final fit by looking for gaps in the fit up.
This is the fiddley spot. Getting the notch for the pivot housing cut in my hand was tricky. To get everything in phase I used a scribe line and aligned the templates, but something still was off once I tack brazed the headtube onto the downtube, so it was just cleaned up by eye mostly.
Notch for downtube to nest into the seattube.
#closeenough for me.
zomg no $500 welding boots.
Downtube ready to mate up with the bb/seattube polo mallet.
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07-30-2014, 03:45 PM #17Registered User
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Weight. I've been asked by more than a few people "Steel? Is it going to weight 50lbs?"
Current weight of trimmed tubes including the main pivot axle is 2.81 kg (6.19 freedom units). This doesn't include the dropouts or the front shock mount. There is some trimming to be done on the rear triangle tubes, so that will balance out maybe the shock mount.
My goal is about 3.6kg with shock and rear axle.
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07-30-2014, 03:47 PM #18Banned
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07-30-2014, 03:58 PM #19Registered User
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Wing and a prayer.
I scribed a line down the length of the tube. The mitre templates were then all lined up according to that scribe. This got things close.
Once I tacked the headtube in place I then laid the sub-assembly on my little chunk of granite (old countertop section left in the garage by previous owner) and used the square side of the pivot housing to see how square it nested. Some adjustment filing to get it close.
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07-30-2014, 04:05 PM #20Banned
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I forget how you're cutting miters. All filing? Some snip/nibble? Grinding? Not holesaw?
Anyway, I think that's pretty adventurous compared to having a fixture that does all the squaring for you. More like the old Italian dudes and their eyeball/hole/pin technique.
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07-30-2014, 04:11 PM #21
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07-30-2014, 04:24 PM #22Registered User
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Using the one off the Nova site.
Creak, just hand cutting it all with hacksaw and files. Yep this is all old tech style. Eyeball it. A bike doesn't need to be square to 0.05mm to ride well. Hell especially for a mountain bike. I've been reading lots and the old dudes say you really should cut your teeth this way before getting any real equipment.
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07-30-2014, 05:17 PM #23Banned
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I would agree, learning and practicing precision and the patience it requires is better. Maybe a good analogy is riding a rigid 26 bike for a while rather than starting with a fancy FS bike. You can go the quick-gratification route but you don't learn the little things that way.
If your miters are solid, the squaring should take care of itself. I wonder about that 0.05mm notion's acceptance across the population of older longer-term builders. I remember about 10 yrs back talking on the Framebuilder Forum that existed then (a standalone place not the subforum at MTBR and not related to MTBR in any way) and asking about surface plates, how necessary they were, how much tolerance one had before a frame rode wonky. As a practical matter it probably depends most on your own attentiveness to detail and your own patience. For some people working with hand tools is almost foreign, for others a natural thing. Some people can visualize how miters need to look and can see asymmetry or non-true joints, while others need external guidance/assurance provided by fixtures and even then, impatience can render a miter time-consuming. Hurried draws of a file can mean more filing than you needed.
Your success on the first frame must've made hopping to FS easier. Some people wouldn't cross that barrier. I wouldn't 10 years ago, for sure. As with the last one, I'm humbled at your work and eager to see the finished frame here.
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07-30-2014, 06:15 PM #24
Worksafe approved welding crocks ! Nice work.
What if "Alternative" energy wasn't so alternative ?
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07-30-2014, 08:52 PM #25
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