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Old 10-31-05, 05:08 AM   #1
LittlePixel
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I don't want to take much of your time but as you may know my frame bolt was stolen last week and I'm finding these things are *hard* to replace....

So anyway - I managed to get hold of a new 3/8" bolt that basically fits fine apart from the fact the frame still flexes because it doesn't have an 'thread gap' (for want of a better description) in the threads halfway up the shaft like the original one did. This gap (I think) gives enough space for the two threaded surfaces to be properly drawn together before it is properly tightened.

Basically - What I'm asking is if any of you that have a proper bolt could have a look at my diagram below (drawn from memory) and help me out (as accurate as possible) with my missing dimensions:

a = full height of bolt
b = height of threaded area above thread gap
c = height of thread gap
d = height of thread below thread gap

If I know these I can machine (aka dremel/file) the thread off in the appropiate area and get the bike feeling solid again. As apposed to the feeling of riding a bowl of Jello.
Maybe even a hi-res pic posted here would be helpful too..!?!?



My sincere thanks in advance to anyone that can help!
Best regards
Huw

Last edited by LittlePixel; 10-31-05 at 05:14 AM.
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Old 10-31-05, 11:31 AM   #2
andy_is_me
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a: 29mm
b: hmmm, mine doesn't have a threaded part above the gap.
c: 17mm
d: 12mm

wierd that mine is different than yours. i don't know if this helps, hope so.
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Old 10-31-05, 11:41 AM   #3
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Looks like that will be a lot of help. Mine is from memory so in fact mine might not have had the thread at the top that I alleged. I'll set to with a file tonight and will report back with any success. Thanks for your help!
Huw
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Old 10-31-05, 12:05 PM   #4
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Quote:
Originally Posted by LittlePixel
Looks like that will be a lot of help. Mine is from memory so in fact mine might not have had the thread at the top that I alleged. I'll set to with a file tonight and will report back with any success. Thanks for your help!
Huw
Hello there, I wouldn't attack with file yet. From the looks of the picture and descriptions, you just need a 'shouldered' 3/8" bolt... the shoulder (part without threads) will be a larger diameter than the 'threaded' part. If you file the threads at the top, you'll be in worse shape. If indeed your 3/8" bolt is the correct thread pitch for your application, just go down to the hardware store and get a 'shouldered bolt' of the same pitch, if it is too long, than just hack some threads off to get close. Also, it looks like the handle of the original provides quite a bit of leverage, so, you'll need to be able to excert considerable force tightening the bolt. Maybe a 'hex head' bolt would be better in this application until you can find the proper fastener.

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Old 10-31-05, 12:14 PM   #5
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Thanks for your input. I see what you're saying but in fact it's a pretty strange setup in that there is a threaded bit at the top which a shouldered bolt would not be able to pass through so a shouldered bolt - like the first one I bought - is not the way ahead. I've worked out that this top threaded bit is purely to keep hold of the bolt when folded and has no effect on the assembled strength. So I need to make that part thinner than the inner diameter of the thread for it to work which I'm sure I can do by putting the bolt in a drill chuck and filing it away. I will be utilising a hex head for aesthethics as much as strength though of course - who wants a stripped bolt head looking all ugly out of the frame...
Ta for your help though. This forum is great for being helped out in your hour of need...!

huw
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Old 10-31-05, 04:35 PM   #6
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Hang on there. Mine looks like your drawing. Let me go measure.

Last edited by icithecat; 10-31-05 at 04:50 PM.
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Old 10-31-05, 04:43 PM   #7
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a=43mm
b=13mm
c=18mm
d=12mm

'b' has two thinnish nuts on it tightened together to create a 'stop' and one loose washer.
So, 'd' are the threads to tighten the frame and 'b' is used to fix how far into the frame the bolt goes.

Edit. I should clarify. The 'b' threads do not even go into the frame. The narrower threadless 'c' and the threaded 'd' parts do.

Last edited by icithecat; 10-31-05 at 05:00 PM.
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Old 10-31-05, 06:17 PM   #8
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Quote:
Originally Posted by icithecat
a=43mm
b=13mm
c=18mm
d=12mm

'b' has two thinnish nuts on it tightened together to create a 'stop' and one loose washer.
So, 'd' are the threads to tighten the frame and 'b' is used to fix how far into the frame the bolt goes.

Edit. I should clarify. The 'b' threads do not even go into the frame. The narrower threadless 'c' and the threaded 'd' parts do.
after reading this i popped that black rubber dust cover thing off mine, and there it was. same as above.
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Old 10-31-05, 06:18 PM   #9
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Thanks ici - You've proved my suspicions. Now I just need to spend some time with that dremel. Should have a lovely tight fix when I'm done though...
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Old 10-31-05, 06:21 PM   #10
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Quote:
Originally Posted by andy_is_me
after reading this i popped that black rubber dust cover thing off mine, and there it was. same as above.
You have a rubber dust cover? Damn. I must be on the hunt. I bet I can modify a sparkplug boot.
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Old 11-01-05, 08:49 AM   #11
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Quote:
Originally Posted by icithecat
. . . 'b' has two thinnish nuts on it tightened together to create a 'stop' and one loose washer. . .
If you care to replace them, the thin nuts are known as jam nuts.

When the frame is bolted in its riding position, is it the upper or lower threads that hold it closed?
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Old 11-01-05, 09:10 AM   #12
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I think the upper threading in the frame (front half) is merely there so that the key doesn't fall off when the bolt is clear of the lower threading and hinged around. The problem with a normal bolt is the thread tightens both and hence locks the top and bottom parts of the frame at a non movable distance from each other so it doesn't really tighten the two plates properly; Having no thread in the top part means they can draw together when tightened and as such achieve a fast and strong join. I think
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Old 11-01-05, 03:14 PM   #13
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BTW, your technical illustrations ROCK!
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Old 11-01-05, 03:20 PM   #14
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Ta! You can't beat the smell of Adobe Illustrator in the morning!

So I've gone mad with the dremel (every home should have one) and ground off about 17mm of thread from the top half of the bolt. Would have taken hours with a hobby file but the 'mel got it sweet in about 10 minutes. Now it is as they say here - 'as tight as a gnat's chuff'.

So I suppose this thread is closed now. Thanks for all the help everyone. Nice to have my ride back to normal. Actually better than normal - no handle threatening to knock my knees and new TT bars making it about a ton lighter and sportier to boot. I may post a pic on the sticky thread when I get a moment.

Huw
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Old 11-01-05, 10:58 PM   #15
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Did you happen to luck out and have a bolt head the same as the axle nuts?
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Old 11-02-05, 04:17 AM   #16
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No but it has an Allen head that fits the biggest key on my swiss army-style multi-tool which I carry about all the time... Just rode into work - solid as a rock - Yay!
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Old 11-04-05, 05:45 AM   #17
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@ Pixel

I've been away too long from these boards, i missed your thread untill now otherwise i would def. have measured mine! Any chance you could please post a picture of your finished product?! This could be really handy if someone else gets the same problem (i have always been paranoid about some joker messing with my bolt too!)

That technical drawing is indeed the Muts Nuts! Nice... i'd like to be able to do that, as i am in process of designing my future home. How long did it take you to learn to use that program like that?
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Old 11-04-05, 06:11 AM   #18
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Of course I'll post up a picture; I'll sort one over the weekend. I'll premiere my new TT bars and generally stripped back to basics look too!. (apart from ugly rear mudguard the london weather is warranting right now).

I've been using Illustrator for about 12 years now so it's hard to be accurate but it's pretty easy to pick up - especially if you do the tutorials or get a 'how to book'.

It's not a 3d CAD system - so maybe not exactly what you'd need for a house design but it's very accurate so it depends what you are doing (sounds like an interesting project!). I mostly use it for my graphic design work...
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Old 11-04-05, 06:40 AM   #19
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Well Pixel, what i am actually planning to do is to build a Ecological Autartic/autonomous (makes own solar elec, filters own water do you can drink it, has geothermic heat retention so no heating needed) Earthship/Cob Hybrid.

Now this my sound very complex but the beauty is that it is actuallty rather simple, dirtcheap and bulletproof (kinda like the twenty).

If you got no idea what the heck i am on about just check 'Earthships' and 'Cob Cottage' in google. The thing is that Cob is so easy/free form/soft and forgiving a way to build walls that i envision elderly/women/high school fieldtrippers everyone coming to help for a few days and sorting the walls. The excavation of the earth sunk earthship type thing would take a day with a Caterpillar backhoe. All that is left to do after these steps is a simple roof and installing the south facing glass as well as interior systems which i would like to take my time for, couple of months. In theory you end up with a very cheap house that has almost no running costs and outperforms all modern housing. Of course building costs and especially codes in EU are prohobitive so i also plan to emmigrate to either Australia or New Zealand (have taken quite some steps in that direction) and do it there. I fancy a change, decent climate and space anyway..

Anywwwwaaaayy (you are still following me ha ha?) i think having a real good floor plan and other drawings would make it even easier to envision and to get others to help. Hence one day i will need to make them... Maybe i could retain your services hmm....
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Old 11-04-05, 07:21 AM   #20
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Sounds like a brilliant (and ambitious) plan. My girlfriend and I covet thoughts of trying to build something a bit less impactive one day but it does seem so daunting. I wish you well!
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Old 11-04-05, 09:46 AM   #21
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Yea, v1nce, best wishes on that undertaking. I would be interested in following your progress on that housing project. You ought post a blog or something on the steps - lots of interest out there, I'll bet.
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Old 11-04-05, 10:55 AM   #22
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I definately will post my progress when it is in the somewhat later stages.
If you guys would like more info now check my page (articles ->)

http://www.rhizomes.nl/sustainable%2...iscussion.html

http://www.rhizomes.nl/beyond%20squa...20housing.html

Or even better, you guys could have a look at the existing earthship in Brighton or the dozens in Taos New Mexico.

Cool that people are interested, i figured i might post something here some day as many cyclist are eco/freedom minded...
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Old 11-13-05, 08:02 AM   #23
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Thanks to everyone that helped me out on this - as promised a few pix and a final sizing guide just in case this happens to any other proud Twenty owners...

First up - sizing
What you need is a 3/8" bolt; I went for one with an allen head in stainless steel so I don't get rust stains all over the paintjob. The length of the bolt you see here was 1" but any length up to 1 1/2" will seemingly fit.

The hard bit was stripping the thread off the top end so the frame would pull together rigidly when the bolt was tightened. Ideally I would have done this on a lathe for a nice clean finish, but I don't have a lathe and as you can see from the pic a good going-over with a stone-bit on the Dremmel did a satisfactory if not madly elegant job. I stripped off about 17mm of thread though any amount between about 15mm and 20mm would do it. You just need strip off enough so that no threaded part of the bolt is locked into the thread of the top plate in the frame as this 'locks' a fixed-height gap between the two plates and means the bolt is tight but the frame plates are not.

With an allen head it's a bit less prone to theft though of course now I've been stung I'm sure I'll probably be a bit more careful about removing it when leaving it outside anyway.


Red stuff is grease


Easy to remove with pocket bike multitool


And it fits!
And I don't bang my knee on the handle!
Yay!

Secondly - seeing as it's had a new saddle, carbon post, 56t chainring, fixed gear and new stem/TT Bullhorn bars /emergency-brake fitted since last posted I thought I'd share a few shots of the little fixed gear minx... Mudguard looks a bit poo but better that than my trouser seat looking like it is covered in same...




Again - thanks to everyone for their help on this!
Huw

Last edited by LittlePixel; 11-13-05 at 08:12 AM.
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Old 11-13-05, 10:33 AM   #24
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She is looking mighty fine! Thanks a lot for all that info and those pics. I was wondering how are the bullhorns working out? I love the look of them but was always worried about not enough hand positions/painfull shoulders or wrists. What is your take on them?
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Old 11-13-05, 02:20 PM   #25
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I'm getting used to the bullhorns; It took a few tries to get the geometry right for me but it's pretty good now though it's definitely a harder ride for the wrists - even with gel-filled gloves.... But they look sweet and are about a third as light as the steel originals...
Huw
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