Square tube, or round?
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Forum Name: Building
Forum Description: Anything to do with building HPVs
URL: https://forum.bhpc.org.uk/forum_posts.asp?TID=5255
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Topic: Square tube, or round?
Posted By: DavidAger
Subject: Square tube, or round?
Date Posted: 20 February 2016 at 3:16pm
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Hi all, Just want to say hello. I'm a newbe to this forum,club an HPVS, or any forums come to that. I don't have an HPV as yet but hoping to build one! I've found some plans on AtomicZombie, the tomahawk (SWB low racer)looks good to me except they use square box tube and I would prefer round. I'm aware that it will be more difficult, but I think I can cope with that. My main problem is if I use round tube which would be the best size to replace the 1.5mm box tube? Any ideas please? Thanks for reading this, and might see you at the first meet, looking for ideas.  David Ager AKA David ------------- He who has choice has torment! |
Replies:
Posted By: AlanGoodman
Date Posted: 20 February 2016 at 5:17pm
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Welcome David! There are quite a few builders on here so I'm sure somebody that knows what they are talking about will be along soon...  In the meantime it might be worth grabbing a copy of SYWTB, our guide, the latest edition of which was put together by Mike Burrows. http://shop.bhpc.org.uk/so-you-want-to-build-an-hpv" rel="nofollow - http://shop.bhpc.org.uk/so-you-want-to-build-an-hpv ------------- |
Posted By: DavidAger
Date Posted: 20 February 2016 at 5:29pm
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Thank you for the welcome Alan, and the info, I'll look forward to any reply. David ------------- He who has choice has torment! |
Posted By: GeoffBird
Date Posted: 20 February 2016 at 6:19pm
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Hi David, As you are probably aware, tube is stiffer in bending and torsion than square box-section for the same weight, but box-section is easier to mark out, mitre and jig, which is probably why Atomic Zombie use it. It is difficult to give advice without seeing the design you plan to build. If you post a link then we can have a look. All I can say at this stage is that you will make a lighter bike if you can find 18 swg (1.2mm), which is not always easy in the larger diameters but possible and worth the effort. I've used 1 3/4" diameter by 18 swg ERW. My first bike was 1 1/2" x 18 swg box, which worked fine for a short wheelbase bike. ------------- Right Time - Right Place - Wrong Speed |
Posted By: GeoffBird
Date Posted: 20 February 2016 at 6:29pm
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Ah, okay, found the Tomahawk. I'd advise building a 'straight-tube' framed bike as a first project, they are much easier to make, lighter and easier to ride, not to mention less daunting to ride in traffic. A 'Z-frame', like the Tomahawk, has a lot more joints and are much harder to weld straight. I have built a number similar machine with round tube (mostly with 1 3/4 diameter x 20 swg T45 but that is very expensive stuff!). I would certainly recommend adding a gusset around the head-tube to the Tomahawk design as this stiffens the frame considerably. PS: You can see some of my pre-2007 bikes here: http://www.facebook.com/media/set/?set=a.1427371618750.56189.1666613055&type=1&l=ef1066e86a" rel="nofollow - https://www.facebook.com/media/set/?set=a.1427371618750.56189.1666613055&type=1&l=ef1066e86a
------------- Right Time - Right Place - Wrong Speed |
Posted By: AlanGoodman
Date Posted: 20 February 2016 at 6:46pm
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Have you ridden any recumbent bikes so far David? As Geoff says lowracers are a little more tricky to get on with. Harder to get started on hills, a little awkward at junctions. I wouldn't ride one in heavy traffic myself to be honest. Something like the Atomic Zombie Spirit would be easier to ride while getting the hang of it.. http://www.atomiczombie.com/Spirit%20Short%20Wheelbase%20Racing%20Bike.aspx" rel="nofollow - http://www.atomiczombie.com/Spirit%20Short%20Wheelbase%20Racing%20Bike.aspx ------------- |
Posted By: DavidAger
Date Posted: 20 February 2016 at 6:52pm
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Thanks Geoff, I've included the link but must admit I do wonder if it's a bit low for traffic. I can get 50mm x 1.2mm erw tube and perhaps other sizes but I'm still in thinking stage at the moment so can do with as much info as poss. Not looked at your bikes yet but I will shortly. http://www.atomiczombie.com/TomaHawk%20Short%20Wheelbase%20Recumbent%20Lowracer.aspx David ------------- He who has choice has torment! |
Posted By: GeoffBird
Date Posted: 20 February 2016 at 6:59pm
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2" x 18 swg wil make a very stiff frame - my 3rd to 5th bikes used either 50mm x 1mm CDS or 2" x 20 swg T45 (all straight tube designs), but this is very difficult to get now. The 1 3/4" just saves a bit of weight and is stiff enough for most applications. The other thing that concerns me about the Tomahawk is the position of the chain pulleys up by the head tube - they look like trouser-eaters to me :-) . Note in the video how he is riding bow-legged.
------------- Right Time - Right Place - Wrong Speed |
Posted By: DavidAger
Date Posted: 20 February 2016 at 7:06pm
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No I've not ridden one yet. I liked the look of the low racers, perhaps I should leave them for the future as Geoff advised. I can probably make one from just photos so I'm no restricted to plans.I'll have a look at the links that you and Geoff gave me and go from there, so, if you see some one walking around with a tape measure and pad at Hillingdon in April you'll know it's me, if that's allowed of course. Thanks ------------- He who has choice has torment! |
Posted By: GeoffBird
Date Posted: 20 February 2016 at 7:11pm
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Happy to send you scale drawings of some of my bikes if that helps David. I even have CAD models of the more recent ones. The difficult thing to get right is chain runs and chain management in my experience. This is useful link - http://www.framebuilding.com/" rel="nofollow - http://www.framebuilding.com/ - Peter is a very helpful and efficient retailer. ------------- Right Time - Right Place - Wrong Speed |
Posted By: AlanGoodman
Date Posted: 20 February 2016 at 7:11pm
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Allowed?? It's encouraged!! How tall are you?? ------------- |
Posted By: DavidAger
Date Posted: 20 February 2016 at 7:13pm
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Ouch, that could be nasty, perhaps a front wheel drive SWB, that way it will have a shorter chain which must be better, if only for cleaning. 1 3/4" tube sounds good to me. I'm getting there, I've learnt more in the last half hour than the last week. Thanks chaps. ------------- He who has choice has torment! |
Posted By: DavidAger
Date Posted: 20 February 2016 at 7:14pm
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5'10". ------------- He who has choice has torment! |
Posted By: DavidAger
Date Posted: 20 February 2016 at 7:17pm
I've just realised I can reply to individuals, sorry if sent a teply to the wrong person?  ------------- He who has choice has torment! |
Posted By: AlanGoodman
Date Posted: 20 February 2016 at 7:18pm
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Probably a bit on the tall side as I'm a shorta**e... but may be worth having a play on my Kingcycle as you're fairly local... ------------- |
Posted By: GeoffBird
Date Posted: 20 February 2016 at 7:20pm
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Front wheel drive has it's appeal (I managed one with front suspension as well!) but chain management is even more difficult as is stopping it eating your trousers. RWD is easier to engineer.
You are posting correctly. Everyone can see the conversation and chip in. ------------- Right Time - Right Place - Wrong Speed |
Posted By: AlanGoodman
Date Posted: 20 February 2016 at 7:25pm
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I have a very interesting front wheel drive machine here (from an engineering point of view)... I'll hopefully have it at Hillingdon. https://www.youtube.com/watch?v=S9bo2MOyXNA" rel="nofollow - https://www.youtube.com/watch?v=S9bo2MOyXNA ------------- |
Posted By: DavidAger
Date Posted: 20 February 2016 at 7:31pm
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Thank Geoff, plans would be good if you don't mind. I've looked at your collection, wow they're lovely. I didn't realise so much went into it. It seems quite obvious I need to start small. I only had in tensions of building one, not any more. I've already got four two wheeled bike's at the moment so I'll have to find a bit more room somewhere. Kitchen? ------------- He who has choice has torment! |
Posted By: GeoffBird
Date Posted: 20 February 2016 at 7:41pm
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Yeah, I've got two in the dining room at the moment - the cleaner ones, so that's okay ;-) What format can you deal with for the plans? PDF, DXF or just JPEG? It would be easier to send by email. I'll private message you my address. ------------- Right Time - Right Place - Wrong Speed |
Posted By: demondunk
Date Posted: 21 February 2016 at 7:45pm
| We all have to start small , but it becomes very addictive. Built my recumbent lowracer. This is the best place for advice and everybody here are fantastic. |
Posted By: AlanGoodman
Date Posted: 21 February 2016 at 8:18pm
He's right you know, we are... ------------- |
demondunk wrote:Posted By: DavidAger
Date Posted: 21 February 2016 at 8:24pm
I can see that,I'm glad to be on board.  ------------- He who has choice has torment! |
Posted By: AlanGoodman
Date Posted: 21 February 2016 at 8:38pm
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Posted By: Karl
Date Posted: 22 February 2016 at 10:17am
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David, Welcome, Have you considered other materials? Barney built a very nice wooden machine that was surprisingly nice to ride (no reflection on his building ability btw) Another option is to go skip diving for old bikes, as most of the leg work is done for you, all you need to do is repurpose them, break out angle grinder and a welder. http://ceeway.com" rel="nofollow - http://ceeway.com is a good place for cycle frame building materials Shame you're not oop North you could have had a ride on some of mine. Karl |
Posted By: DavidAger
Date Posted: 22 February 2016 at 1:54pm
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Thanks Karl Wood is a good idea, but metal is easier for me as i already have the necessary,perhaps in the future. I have skip diving (I like that phrase) on my list as I've seen a few nice photos. I hope to go to Hillingdon in April, perhaps see you there, although it is "darn sowf"  ------------- He who has choice has torment! |