Crank shells

[bicyclos]

Howdie all

New member to the forum

I have been experimenting with scrap bikes from the skip and made a lwb recumbent. The machine works really well and comfortable to sit on even though it was put together in a crude way. Now I am on to my second build which is a swb. This time I have made a proper jig unit to hold the tubes in place and found a place to buy the mild steel tubes [easyier to weld]. The problem is, the messing about cutting crank shells from old scrap bikes and cleaning them up for my projects is time consuming and they never look good.

Is there anyone in the know of where I could purchase mild steel crank shells which are fitted to the cheaper bikes. I know its not the lightest of materials but the lwb I built out of mild steel is quite light and I can ride up the hills where I live no problems. This next build I want it to look good with mitred joints etc.

Regards

Leon

 

[Riding in Circles]

Bike builders use steel tubing then use a thread cutter and facing tool.

 

[Bokonon]

Hi bicyclos

Do you have any pictures of your experiments? I occasionally toy with the idea of building my own 'bent. As for sourcing bottom bracket shells, thoughts that spring to mind are:

1 - Ask a frame builder. May be expensive and likely to be in a material more exotic than mild steel.
2 - Make your own if you can find tube of the right section, tap the threads (if you can get taps (lh and rh) at a decent price) or cut on a lathe (if you have access to a lathe.)
3 - Carry on as you are, which may be the cheapest option though requires a lot of work.

 

[bicyclos]

Hi there
Thanks for the replies so far. I was in the garage this afternoon working on my swb project and thought the cranks I clean up from scrap bikes dont look all that bad really plus the odd bike I will be building dousn't justify the oulay of expensive thread cutters etc. There is an alarming amount of bikes that do get skipped. I picked up three bikes that some guy was throwing away last week. One was a specialized atb to which I am doing up[bike no.7].

Heres a few photos of my first attempt at diy bike building. It is going to get chopped for a few spares and future builds. The seat was fabricated from a bath which was being skipped at work.

 

[Night Train]

That's a nice bent.
I used to work that way about 30 years ago, still do in some respects. I am working on a bent trike at the moment whenever I have time.

About ten years ago I was asking the same question as you, looking for ready made BB without the rest of the bike attached. A bike shop in Manchester rummaged about in the parts bin and sold me two for about £5. I don't know if bike shops still hold odd frame parts anymore.

 

[mickle]

Hey bicyclos and welcome. I really admire what you have acheived there, a very nice looking bike. Might I respectfully suggest that you do a bit of research into steering geometry before you dive into the next project? It's just that the fork offset isn't really compatible with the head angle you've used, placing the front wheel contact point too far behind the steering centre. It's the reason, as you have no doubt discovered, that the front wheel wants to wander off the straight ahead, particularly at low speed.

There's no shame in getting it wrong, even well respected bike manufacturers do it sometimes. Kona did the exactly the same thing with their Hot Rod.

 

[bicyclos]

Hi there
Thanks for the replies. This bike was only an experiment to see if I could weld metal together. I have wanted to own a recumbent bike for a few years now but unable to afford one. I bought Mike Burrows book at the back end of last year and he has inspired me to give it a go[respect]. I blame Mr Burrows for this obsession

I have spent about 300 pounds on welder and tools to get me started and turned my garage into a workshop-ish. About the steering geometry, I had no choice because of the top tube being bent like a banana denoted where the steering ended up. The bent tube was from a steel framed bed.
I basically chopped the front end of bike "A" welded to tube then chop rear end bike "B" and weld. Stick two wheels on and there you go..

The swb bike project I am on with now is being built with care and attention. I have made a jig to house the tubes secure and the joints are all mitred for a snug fit. I will post some photos as I go along.

 

[bikepete]

Here you go:

http://www.framebuilding.com/Bottom Bracket 2.htm