Any question answered...

What is the best way to run two different back wheels on a geared bike? Have one cassette and chain for each wheel or change the cassette as well when I change wheel?

@oz: 7075 is strongest. I bought from here, back in 2007 a 250mm square of 6mm plate was £24. Most of the online metal shops don't carry 7075, as it's expensive and few hobby projects need the extra strength. 6082T6 is <£6 for the same size from http://www.aluminiumwarehouse.co.uk/cutting_calc.php?gclid=CLbyoaq6vq0CFS9ItAodtTCf_A

@fussballclub: cassette per wheel, no need to change chain if you don't run your chains down to the last atom of their life

Thank you. Thats what I did. Got complete new drivetrain now; how do I decide when to replace chain?

^ your local bike shop should have a chain wear gauge.

I guess I could make a pattern and router the spider myself, simple enough shape. I think I'll go to the local machine shop and ask them a few questions before I proceed. I could even make a few different spiders for it. Especially as you can get 1,1/8th rings in 104bcd. I'm currently having to use a BMX ring as it's the only 110bcd ring I could find which didn't have shift ramps.

You think it's not worth getting it made in 7075 and 6082 will be plenty strong enough?

http://www.aluminiumwarehouse.co.uk/cutting_calc.php?gclid=CLbyoaq6vq0CFS9ItAodtTCf_A

Going off your link 2x 130x130x6mm is only £3.36! I expected it to be more than that.

Thank you. Thats what I did. Got complete new drivetrain now; how do I decide when to replace chain?

Measure the links.

http://sheldonbrown.com/chains.html#wear

Anyone having this weird issue with Garmin Connect?

You edit a course, then "send to device", and it sends the original to the device.

Sometimes it accepts your changes, but other times not- which makes it doubly annoying.

I'm trying to edit this file http://connect.garmin.com/course/384950#

Which appears to be called "ROTFL" on Garmin Connect, but once sent to device it reverts to its original name "ROTFL 02.10.11", and the start/finish go back to being Herne Hill Velodrome (I have changed them to the road outside my house in the file I am trying to save).

I've got changes to "take" before by repeated cycles of "edit", then "save", but that's not working this time.

Anyone else had this? If so, what did you do?

^^ That sounds reasonably easy.

^ Neil. I uploaded your course onto my garmin then tried opening it in bikeroutetoaster and I get an error message asking me to check the file is in the correct format. It happily opens other tcx files from my device.

It also fails to open on my garmin and the map centres on Lybia. I'm gonna try deleting it and loading it again...

OK, sorted. I copied the course onto my garmin connect account and it's fine now. I suggest you delete it off your account and replace it with this one - http://connect.garmin.com/course/444527

I've no idea where the problem lies and loading your course onto my garmin also carried across the old name. Odd!?

That worked, thanks- however I changed the name to "ROTFL, Taymount Start", just to see if it would pick up that change, and it did not.

http://connect.garmin.com/course/444827

This is really quite odd!

You think it's not worth getting it made in 7075 and 6082 will be plenty strong enough?

7075 is about 60% stronger than 6082. If you are a weight weenie with the FEA tools to exploit this, you could probably knock some weight off if your design analysis shows that strength is the limiting factor rather than stiffness. If you're going to be using a lot of material to keep the stiffness within acceptable bounds, you don't need the strongest alloy. Since most of us hobbyists tend more towards Brunel than NASA when doing engineering calculations, you could probably get away with puny pure aluminium, and 6082 has better corrosion resistance than 7075.

Ok, thanks Tester.

Does anyone have a Garmin Edge 200? I've just got mine. It works fine when up and running, but is taking an absolute age to find a signal. I'd done a quarter of my run today before it finally kicked in - which undermines the whole point of the bloody thing.

No, they often contain a lot of sodium salts, which will promote galvanic corrosion.

Oops.

taking an absolute age to find a signal. I'd done a quarter of my run today before it finally kicked in

Turn it on as soon as you know you're going out (before getting dressed etc.) and stick it on a window sill. It should be locked on by the time you're ready to go out.

I've had it on the windowsill for about 20 minutes now - nothing. Same with the run today (don't laugh at the speed!) - the start point should be where the end point is, but it didn't pick up until then. http://app.strava.com/runs/3155846

At the moment I'm pretty unhappy with it, but everyone else has given it great reviews so I'm wondering if this one is duff.

Got the 305- exactly the same, I normally walk for ~10 minutes to let it lock on. It is annoying.

reckon this'll help?

http://www.gpsreview.net/acquiring-satellites/

My 305 and 500 both lock in within a couple of minutes of going outside. What sort of local geography are you in? The satellites are not above you, they're dotted around just above the horizon, so buildings and trees can easily block the signal.

That run was in Victoria, so obviously pretty built-up. But at the moment I'm in Tooting - just hundreds of acres of two-story houses and I'm currently upstairs at the top of a hill.

Tried holding it out of the window and waving it around a little?

I usually start my runs from the top of Taymount Rise, which is probably the highest point bar Crystal Palace in the area- still rubbish.

What is this type of connector called? Looks a bit like a molex, has 6 pin holes for pins around 1.2mm wide.

is it not mildly ironic that parts of a 3D printer are made on a 3D printer?