Right, so I've got a replacement set of cranks as mine have well and truly done their bit. They're missing the chainring bolt that goes into the crank due to a stripped thread and the BB sounds like an empty spray can with the mixer rattling around inside.
Anyway, after taking note of the yellow warning stickers and extensive instructions on the new cranks I've suddenly become very mindful of something I was already dimly aware of - I have no idea what I'm doing when it comes to jobs like this.
My major concerns are:
- Campy recommend tapping and facing the BB shell. Is this actually necessary?
- Campy also recommend using a torque wrench to tighten the crankbolt. Is this actually necessary?
- I've also got no idea how to get the old BB out. I haven't removed the cranks yet so I can't see what's in there but I'm sure I've read somewhere that a Campy lockring tool will do the job. Does that sound right to anyone?
Any advice gratefully received!
Matt
Replacing Campy Cranks/BB
You don't need to tap and face if it was done properly in the past and the thread hasn't been abused.
Torque wrench makes sure the finished assembly is safe to ride. But if your new crankset is one of the new UT versions, then you need a lot of torque for that centre bolt (as well as the bearing cup). The unit is Nm (Newton Meter) and 1Nm is 1kg of weight applied at the end of a 1m long lever. So if your lever is 25cm long, then you'll need 4kg of weight at the end to keep the eqivalence. Based on this simple ratio and you'll be able to calculate how much weight equivalent force you need to apply at the end of your spanner/wrench... A lot. Just don't hurt your back.
There are different designs (lock ring) for the various Campy levels for those older square taper BB cartridges, and they require different tools. You can source them off eBay (US seller). In my recent case, I just took the frame to a LBS and asked them to do the quick job. For the installation of the new UT crankset, I did it myself. For this, you'll need a bearing cup spanner (shared tool with standard Shimano offering) and a 10mm allen key bolt that has a long extension to get into the middle of the BB (this tool is harder to find and ended up somewhat expensive in my case).
I invested in those tools for the UT crankset system as I want to be able to service them in the future. If you are not keen, then it shouldn't cost much to get a LBS to do the job for you. It really is just a few turns of bolts and spanners. Under 10mins.
Torque wrench makes sure the finished assembly is safe to ride. But if your new crankset is one of the new UT versions, then you need a lot of torque for that centre bolt (as well as the bearing cup). The unit is Nm (Newton Meter) and 1Nm is 1kg of weight applied at the end of a 1m long lever. So if your lever is 25cm long, then you'll need 4kg of weight at the end to keep the eqivalence. Based on this simple ratio and you'll be able to calculate how much weight equivalent force you need to apply at the end of your spanner/wrench... A lot. Just don't hurt your back.
There are different designs (lock ring) for the various Campy levels for those older square taper BB cartridges, and they require different tools. You can source them off eBay (US seller). In my recent case, I just took the frame to a LBS and asked them to do the quick job. For the installation of the new UT crankset, I did it myself. For this, you'll need a bearing cup spanner (shared tool with standard Shimano offering) and a 10mm allen key bolt that has a long extension to get into the middle of the BB (this tool is harder to find and ended up somewhat expensive in my case).
I invested in those tools for the UT crankset system as I want to be able to service them in the future. If you are not keen, then it shouldn't cost much to get a LBS to do the job for you. It really is just a few turns of bolts and spanners. Under 10mins.
Ta Weiyun. I've been nursing these cranks for the past two years but haven't had the foresight to collect any tools in that time so now that I've got the new cranks I'm feeling quite impatient and am inclined to just get it done by a pro as you suggest.
The other thing I meant to mention was people's experience with introducing a new set of chainrings into a drivetrain that has seen significant action. Is it just a case of suck it and see as far as potential wear and tear issues go or are there some absolute no goes when it comes to mixing and matching new and old components?
The other thing I meant to mention was people's experience with introducing a new set of chainrings into a drivetrain that has seen significant action. Is it just a case of suck it and see as far as potential wear and tear issues go or are there some absolute no goes when it comes to mixing and matching new and old components?
If you want to try it yourself, I may have the tools you require, as well as a copy of Zinn's The Art of Road Bike Maintenance.
James
James
Sorry but one KG over 1 meter is 9.8 NM
Torque= Force*radius
Force= Mass*Acceleration (of gravity in this case)
Torque=Radius * Mass * Acceleration
So in this example, mass is 1 kg, accelerationn is 9.8ms-1 (gravity) and radius is 1 m= 9.8NM
Don;t get it wrong, or you will end up with almost ten times as much torque as you need.
Torque= Force*radius
Force= Mass*Acceleration (of gravity in this case)
Torque=Radius * Mass * Acceleration
So in this example, mass is 1 kg, accelerationn is 9.8ms-1 (gravity) and radius is 1 m= 9.8NM
Don;t get it wrong, or you will end up with almost ten times as much torque as you need.
Well, if we are going to get pedantic, then let's remember the rules of SI units, which dictate that there should always be one space between the magnitude and the unit; and that the unit is always written in lower case, except when the SI unit is named after a person (such as Isaac Newton).
In this case the correct units of the expression are:
torque = 9.8 Nm
...which cannot be confused with
nm - nanometres,
or NM - MegaNewtons (although this one breaks the SI protocol of placing the prefix after the SI unit, to further add to the ambiguity.)
In this case the correct units of the expression are:
torque = 9.8 Nm
...which cannot be confused with
nm - nanometres,
or NM - MegaNewtons (although this one breaks the SI protocol of placing the prefix after the SI unit, to further add to the ambiguity.)
OMG, have I forgotten that much of my high school physics and math?!? 
I'll have to have another flip through of those texts.
I'll have to have another flip through of those texts.
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