500mm long and 38mm overall diameter we’re going to try and make it stiffer than stock with a wall thickness of 1.2mm<\/strong>. Hang a 20kg weight off the end of it and the end will flex by…<\/p>\n…umm…<\/p>\n
…takes of shoes and socks to start counting on toes…<\/p>\n
…carry the one and take away the number you first thought of…<\/p>\n
\u00a03.2mm deflection.<\/strong><\/p>\nNow let’s compare that with a 500mm tube with a 45mm overall diameter with a wall thickness of 0.9mm<\/strong>. Banging the numbers through we get a figure of<\/p>\nOoo, look, 2.5mm deflection!<\/strong><\/p>\nNice, so we know it’s stiffer but it must be heavier, right? Let’s have a look…<\/p>\n
How heavy?<\/h3>\n
Mass = density x volume which in our case is<\/p>\n
mass = D( \u03c0(r2<\/sub>2<\/sup>\u00a0– r1<\/sub>2<\/sup>)L )<\/p>\nFor grade 9 Titanium the density is around 4480 kg\/m\u00b3<\/p>\n
For our first 38mm<\/strong>\u00a0x 1.2mm <\/strong>tube that’s 310 grams<\/strong><\/p>\nand for our second 45mm<\/strong>\u00a0x 0.9mm<\/strong> tube it’s 279 grams!<\/strong><\/p>\nQED – we can make a tube stiffer, with the smallest increase in weight, by making the overall diameter larger instead of\u00a0increasing\u00a0the wall thickness.<\/strong><\/p>\nWhen do we stop?<\/h3>\n
So you could just carry on making the tube larger and larger while making the wall thickness thinner and thinner? Err, no.<\/p>\n
As you might imagine there’s a practical limit to how thin you can make the wall thickness of a tube before it starts acting like a coke can and becomes easy to crush!<\/p>\n
I’ve seen titanium bike tubing quoted as thin as 0.6mm in the center of double butted sections (it’s still 0.9mm on the ends) but 0.7mm is the more common thickness used. If common is the right word, of course, double butted tubes are still quite rare because of the extra costs associated with making them…<\/p>\n
Wow, well done for making it this far! Do let me know if my sums look wrong, but I think I’m there – in the mean time stay tuned for some \u00a0more Gallery posts of people’s fine rides…<\/p>\n
\n- <\/dd>\n
- <\/dd>\n
- <\/dd>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
Here we go, I promised myself I’d dig some numbers up to prove this… Bigger or thicker? One of the common things people do to increase the stiffness of a frame is to increase the wall thickness of the tubing, typically going up from 0.9mm to 1.2mm. Now most commercial […]<\/p>\n","protected":false},"author":1,"featured_media":2077,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[8,14,5],"tags":[7,6],"class_list":["post-2016","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-frame-building-notes","category-gallery","category-news","tag-framebuilding","tag-news"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9GLNb-ww","jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":4319,"url":"https:\/\/spanner.bike\/?p=4319","url_meta":{"origin":2016,"position":0},"title":"Kevin’s XXL Titanium 29+\/Fatbike from XACD","author":"andrew","date":"13th September 2020","format":false,"excerpt":"Someone (Hi Alex!) reminded me that a) Some of you are still reading this blog and that b) I've not put much content up recently. OK, I can take a hint! I've been busy crafting up frames for customers as my alter ego 'Spanner Bike', more of which later. But\u2026","rel":"","context":"In "Bikes"","block_context":{"text":"Bikes","link":"https:\/\/spanner.bike\/?cat=13"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2020\/09\/Aey4GlDrRMyeTeyODRQqQ_thumb_252a-900x654.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2020\/09\/Aey4GlDrRMyeTeyODRQqQ_thumb_252a-900x654.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2020\/09\/Aey4GlDrRMyeTeyODRQqQ_thumb_252a-900x654.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2020\/09\/Aey4GlDrRMyeTeyODRQqQ_thumb_252a-900x654.jpg?resize=700%2C400 2x"},"classes":[]},{"id":382,"url":"https:\/\/spanner.bike\/?p=382","url_meta":{"origin":2016,"position":1},"title":"Spanner’s Love You Long Time by XACD","author":"andrew","date":"14th October 2009","format":false,"excerpt":"And number two rolls off the production line: Based on this drawing: This time I'd been reading up about the latest hardtail thinking around geometry and tube sizes. It's got a much more contemporary spec to it which has sorted the handling. Compared to Ti-Bride the top and down tubes\u2026","rel":"","context":"In "Bikes"","block_context":{"text":"Bikes","link":"https:\/\/spanner.bike\/?cat=13"},"img":{"alt_text":"LYLT2","src":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/07\/LYLT2.JPG?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/07\/LYLT2.JPG?resize=350%2C200 1x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/07\/LYLT2.JPG?resize=525%2C300 1.5x"},"classes":[]},{"id":3209,"url":"https:\/\/spanner.bike\/?p=3209","url_meta":{"origin":2016,"position":2},"title":"Review: Works Components Angleset, here’s project chopper…","author":"andrew","date":"23rd October 2016","format":false,"excerpt":"Slack-curious? You may well have\u00a0spotted that mountain bike head angles are getting slacker. Modern 'enduro' bikes are headed towards 65 degrees which used to be reserved for\u00a0full on downhill bikes until just recently. Should you go slack in your new frame or play it safe with some less aggressive angles?\u00a0\u00a0Can\u2026","rel":"","context":"In "Framebuilding Notes"","block_context":{"text":"Framebuilding Notes","link":"https:\/\/spanner.bike\/?cat=8"},"img":{"alt_text":"Viola, one test rig: a standard issue, excellent handling, perfect for UK conditions Nukeproof Mega TR.","src":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2016\/10\/DSC_0195-1-900x600.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2016\/10\/DSC_0195-1-900x600.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2016\/10\/DSC_0195-1-900x600.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":3965,"url":"https:\/\/spanner.bike\/?p=3965","url_meta":{"origin":2016,"position":3},"title":"Spanner Bike – Project S.Y.D. aka the ultimate Titanium Hardcore Hardtail by Titan","author":"andrew","date":"30th April 2018","format":false,"excerpt":"It's getting late now, maybe 10 or 11 at night and the garage is pretty chilly. I've got a furrowed brow and I'm starting to get stressed. For the past few hours I've been feeding various cables in and out of the frame trying to work out if the 'impossible'\u2026","rel":"","context":"In "Bikes"","block_context":{"text":"Bikes","link":"https:\/\/spanner.bike\/?cat=13"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2018\/04\/DSC_0189-e1524912727919.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2018\/04\/DSC_0189-e1524912727919.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2018\/04\/DSC_0189-e1524912727919.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2018\/04\/DSC_0189-e1524912727919.jpg?resize=700%2C400 2x"},"classes":[]},{"id":379,"url":"https:\/\/spanner.bike\/?p=379","url_meta":{"origin":2016,"position":4},"title":"Spanner’s Ti-Bride by XACD","author":"andrew","date":"14th October 2009","format":false,"excerpt":"The one that started it all; Ti-Bride looks like this: And was spawned from this drawing: \u00a0 As I've mentioned elsewhere this was my first attempt at a titanium frame and while it turned out OK there were a couple of issues which made me want to have another go\u2026","rel":"","context":"In "Bikes"","block_context":{"text":"Bikes","link":"https:\/\/spanner.bike\/?cat=13"},"img":{"alt_text":"Spanner TiBride - the first 'prototype'","src":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/05\/tibride.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/05\/tibride.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/05\/tibride.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2009\/05\/tibride.jpg?resize=700%2C400 2x"},"classes":[]},{"id":9701,"url":"https:\/\/spanner.bike\/?p=9701","url_meta":{"origin":2016,"position":5},"title":"Jeff’s Custom Titanium Spanner Bike Quadpus Fork","author":"andrew","date":"18th August 2020","format":false,"excerpt":"Quadpussin' it. You might remember Jeff from the last post - he had a finely crafted replica of his favourite frame made in titanium. Well... It turns out he was so happy with the frame that he couldn't resist taking me up on a special offer to compliment it with\u2026","rel":"","context":"In "Bikes"","block_context":{"text":"Bikes","link":"https:\/\/spanner.bike\/?cat=13"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2019\/08\/DSC_0545-e1565561839767-712x900.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2019\/08\/DSC_0545-e1565561839767-712x900.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2019\/08\/DSC_0545-e1565561839767-712x900.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.spanner.org.uk\/wp-content\/uploads\/2019\/08\/DSC_0545-e1565561839767-712x900.jpg?resize=700%2C400 2x"},"classes":[]}],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/spanner.bike\/index.php?rest_route=\/wp\/v2\/posts\/2016","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spanner.bike\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spanner.bike\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spanner.bike\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/spanner.bike\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2016"}],"version-history":[{"count":0,"href":"https:\/\/spanner.bike\/index.php?rest_route=\/wp\/v2\/posts\/2016\/revisions"}],"wp:attachment":[{"href":"https:\/\/spanner.bike\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2016"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spanner.bike\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2016"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spanner.bike\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2016"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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<\/a>