One gear..... one idea

Some of you might have seen my madcap wooden bike that's under construction in the Current Projects forum. I set up a website to document it but have also started a blog to post about random bike related things.

First post is about the physics of getting up hills on a singlespeed and why it's really not as bad as our geared comrades would like to believe.

WARNING it gets quite geeky (read: I get quite geeky). You've been warned, so no apologies from this point on!
http://ligneusbikes.wordpress.com/blog/

EDIT: I've just realised that I did the whole article based on a crank length of 120mm! Not sure where that came from. Using 170mm completely changes the final answer..... and conclusion. Doh! I'll have a think about it today and update the post with the right numbers.

EDIT 2: Updated and reposted with the right numbers. Sorry!

fucking, awesome!

i actually enjoyed the section 'why wood' a lot. educational.

brilliant. really enjoyed that. thanks man.

Just read about the lowracer - excellent! In vague answer to some of the questions within the text, yes all recumbents are pretty heavy unless you're paying through the nose for top end Challenge or Velokraft offerings. - can't escape the fact that you need thicker tubes (trunks?) than a diamond frame. And they're all not so much difficult to ride as different.

I'm assuming the Wooden Fish On Wheels had wood somewhere in it too...

EDIT: I've just realised that I did the whole article based on a crank length of 120mm! Not sure where that came from. Using 170mm completely changes the final answer..... and conclusion. Doh! I'll have a think about it today and update the post with the right numbers.

Fixed and reposted with the right numbers. Fortunately/ unfortunately I'd also assumed that you got full lever arm on the cranks on the full revolution. When I took this into account it pretty much cancelled out the other mistake I'd made on the length of the cranks. Phew! I'm sure you guys had noticed the mistake and were just being polite.

Spot any more errors?

That amazingly rare blend of technical interest, simply explained science providing answers to an issue with eminent readability. Brilliant!

Now I understand why I went triple and have 30x29 at my disposal.

That 2x4 bike is amazing.

Good stuff

Does wrenching up on the bars have any effect overall?

The short answer is yes, a bit, and that is built into my 'pulling up force', but it doesn't have as much effect as it feels like it should.

When you stand up out of the saddle all your weight goes on one foot on one side of the bike and unbalances the bike. If you didn't have your hands on the handle bars this would cause the bike to fall over to the side that you're pushing on. You then need to put an opposing push/pull on the handle bars to stop it falling over. Thats why getting out of the saddle on a fixie skidder with cut down handle bars is much harder because you don't have much lever arm on the handle bars. This doesn't happen when you're sat in the saddle because the out of balance force goes up the seat tube and the seat pushes against your arse cheek/ inner thigh and balances. So a lot of the yanking that we tend to do when we're out of the saddle grinding up a hill is purely to keep the bike upright but a bit of this does go into helping you push harder.

Rather than extreme yanking on the handle bars you can reduce the ammount you need to pull by leaning the bike away from the foot you're pushing with to try and keep your weight over the wheels as you transition from foot to foot. Although you still need to work fairly hard with your upper body to shift the bike from one side to the other as you're leaning it in the opposite direction to the way it wants to go.

Riding like that ^^ does make you look like a total dick though. Seems as if it is quite inefficient too, as you're doing weird things to the force planes...

A proper sciencey answer, thanks.

really good stuff man. I love it!

reminds me of the fella making a bike out of Fibreglass.. made some great arguments as to why it would perform like carbon fibre but at a fraction of the cost..

[QUOTE=Dramatic Hammer;2771517]Riding like that ^^ does make you look like a total dick though.QUOTE]

Thats true. Don't come to me for style advice!