Thursday, November 27, 2008
Installing the rear derailleur
Bored with working at the front, now I shall do something to the rear of the bike. The black piece is a plastic spacer to prevent frame damage during delivery. I keep hold of things like this for when I transport my bikes anywhere and they don't have a wheel installed. Helps prevent damage from bending the frame due to over enthusiastic piling up of kit on top. The part furthest away is where the rear disc brake calliper screws on, and this side has the hanger where the rear dérailleur is fitted.
The rear derailleur screws into this hole here, on the hanger. Suppose it is called the hanger as it hangs down. If you look carefully it looks a little like a comma, the little 'tick' is a stop for a part on the derailleur that is used as a thrust plate to resist the twisting motion imparted when one tensions the cable to change gear. So it is important that the stop goes on the correct side, although it is usually difficult to get it wrong. On some derailleurs there is no plate, just a bolt. In that case the blot pushes against this tick.
Goes on really easy. I just screw the derailleur hanger bolt into the hanger. I check several times to make sure it is correct as it went on way too easy. Then I torque the hanger bolt up as per the instructions.
I prefer the SRAM system for the rear derailleur as they use a parallelogram arrangement for moving across the cassette, this ensures the cage can never contact the cassette. On other systems they rely on the chain tension to pull the cage down. When a MTB gets really dirty in a race you can forget about chain tension doing anything like when you set the bike up, so I don't bother with anything less.
Reckon it is time for another beer.
The rear derailleur screws into this hole here, on the hanger. Suppose it is called the hanger as it hangs down. If you look carefully it looks a little like a comma, the little 'tick' is a stop for a part on the derailleur that is used as a thrust plate to resist the twisting motion imparted when one tensions the cable to change gear. So it is important that the stop goes on the correct side, although it is usually difficult to get it wrong. On some derailleurs there is no plate, just a bolt. In that case the blot pushes against this tick.
Goes on really easy. I just screw the derailleur hanger bolt into the hanger. I check several times to make sure it is correct as it went on way too easy. Then I torque the hanger bolt up as per the instructions.
I prefer the SRAM system for the rear derailleur as they use a parallelogram arrangement for moving across the cassette, this ensures the cage can never contact the cassette. On other systems they rely on the chain tension to pull the cage down. When a MTB gets really dirty in a race you can forget about chain tension doing anything like when you set the bike up, so I don't bother with anything less.
Reckon it is time for another beer.
Labels: building a bicycle, cycling
# posted by threaded @ 11/27/2008 05:55:00 am 
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Look 'ere threaded, you are about four months too late with this advice, having failed to fix the geary thing on my cheap made-in-Eastern-Europe Halfords bike I took it to the dump back in July.
# posted by 
: Fri Nov 28, 09:05:00 pm CET
: Fri Nov 28, 09:05:00 pm CET
Bicycles such as you had are never meant to be repaired, they are like disposable razors, and last about as long: use for a week or so whilst the weather is good and then thrown away.
The kind of bicycle being built here is meant for use in appalling conditions. I believe this type of rear derailleur costs more than those bikes you had. It will certainly last an awful lot longer.
With bicycles it is often truly the case of you get what you pay for.
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The kind of bicycle being built here is meant for use in appalling conditions. I believe this type of rear derailleur costs more than those bikes you had. It will certainly last an awful lot longer.
With bicycles it is often truly the case of you get what you pay for.
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