Friday, May 27, 2011

BSD

Today is a day of learning new things - acronyms love them or hate them they are here to stay. I was looking to replace my chainring from 42 teeth to something a little smaller. I am not small in the thigh department but I am not Chris Hoy! Riding up fire roads and hills in Surrey although short is strength sapping. Last weekend if it had not been for riding with an 11yr old who lacks the strength and technique I would have been plastered all over the hills in a state of exhaustion. Ally this with the fact that I rarely went past 7 on the rear shifter and you can see that I am wasting machinery. Perhaps one day I will have the strength and speed to peddle downhill at full tilt, but lets not run before we can walk.

So to replace the front chainring that I got with the bashguard and retention device (latter of which is currently off the bike because of chaincross). Looking on the usual suspects I find that the cost is around £30-40, which is out of my range for a good few months, even if I flex plastic. When Uncle Riotious puts me onto BETD via Howard at Pedal and Spoke. £18! Cushty! 38 teeth will take me into the realms of comfortableness a little bigger than the average middle chainring, so I should still have more oomph for the quick bits but I should be able to ride up hill on at least one back cog higher if not two.

Now to choose the Goldtech chain ring. Hang on what is this PCD in the options? Erm they have BCD in the text? Bolt something clearly. Isn't the internet a wonderful thing BCD (bolt circle diameter) right there on Wikipedia and PCD (pitch circle diameter) on the same page. Phew, all they want to know is what is the distance between the opposite bolts. But I have discovered that this is important in replacing this part and so I won't be picking up any sale items with the wrong BCD in future. Just when you think you have this bike mechanic stuff sorted it just comes back to bite yer.

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