Sunday, September 7, 2008

Commuter bicycle

First Scott, then Specialized. Then come the third "S" in my cycling life.. SHOGUN!

While the first 2 I don't dare to leave it out there while running errands, this bike I built with ease of mind concept. Meaning I can confidently leave it out there and that it won't attract much attention. Worst case if it's stolen, it doesn't burn big hole on my pocket. Having said that, I still keep the bicycle lock out there.

Here's the objective in importance order: -
1. Dirt cheap
2. Simple setup
3. Can ride town elevation

As a result, this was the plan..
1. Single front v-brake
2. Single speed
3. Upright riding posture

I had my hands on the frame, fork & headset for sub RM100. Others: -
Saddle - RM15
Stem - RM30
Handlebar - RM15
Handle grip - RM8
Front wheelset - RM20
QR seatpost clamp - RM10
V-brake - RM15
Crankset, pedal, cassette, chain, rear wheel, tyres, brake lever - parts surplus

That's meeting all the objective and plan except riding town elevation on which I can't determine at this current moment. Why?

Running single speed is a delicate matter of striking a balance of speed and strength. Secondly, chainline.

Striking a balance
The gear ratio is the key element on determining what fit you best for most of terrain you ride. Running it high, you can speed up on flat, suffer on climb. Running it low, you may take any climb, but can't go fast on flat.

Previous setup, 32T:14T (2.28 ratio)

I'm trying on 44T:14T (3.14) ( meaning 1 revolution pedal drives 3.14 turn of rear wheel). On flat and short climb seems not that difficult. I am yet to take it to work where elevation varies.

The chainring is ideally to be aligned to rear sprocket, as nearly straight line adjustment as possible. Sheldon Brown has a lengthy explanation on this subject.

Adjusting the chain line was pain in the ass

If running on cassette type hub, this means stacking a number of spacer to achieve this and probably fitting large chainring in the middle chainring position.

Stacking spacers, scavenge from old cassette

Final pose on 6th September

Foot note: Initially I was using "commuting bicycle" on which refer to a "bicycle as mode of transport that we use to commute". It's similar to "jogging shoe" and "running shoe" if we look from the same context. However, commuter in some part of the world means "a piece of transportation equipment used for the transportation of such persons" thus our "KTM Komuter".

No comments: