2015 Cycling thread

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Puff. :lol:

Shouldn't be a problem - chainrings operate on a BCD thingy, so as long as they're the same, you can do what you want. I.e. If your big ring is a 5 arm, 130bcd ring, you can put any 5 arm, 130bcd chainring on. Same for the little ring.

Mind, how much are the chainrings? Whenever I've looked into it, its been more cost effective to buy a new crankset.
 


Walter Ego said:
Puff. :lol:

Shouldn't be a problem - chainrings operate on a BCD thingy, so as long as they're the same, you can do what you want. I.e. If your big ring is a 5 arm, 130bcd ring, you can put any 5 arm, 130bcd chainring on. Same for the little ring.

Mind, how much are the chainrings? Whenever I've looked into it, its been more cost effective to buy a new crankset.
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Seen a 105 compact crankset for 70 quid ish so as you say can't imagine chainrings would be much cheaper..

Long slow rides on heavier winter bike mean 53/39 is wasted really..
Summer/ turbo bike don't want to drop much below 52.

This 32/34 on holiday has spoilt me man:lol:
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Didn't use the biggest 3 or four sprockets but at least they were there.

Stay with the clarion in the end then ?
 
Cee Jay said:
After a bit advice, probably Al/Walter or anyone else feel free to chip in.

Wanting to re jig two of my bikes and I'm wanting to know what's compatible groupset/shifter wise etc ?

Winter bike currently 105 groupset with 53/39 10 speed. Guessing no problem with converting to a compact ?
Could I just buy chainrings( 50/34) rather than buy new crankset ?

Summer bike
Currently Ultegra 10 speed 53/39- Could I change this to one of these super compacts( 52/36) and would I again be able to just buy the chainrings only or would I need whole new crankset ?

If I've got to buy new cranksets I've seen them cheap enough, but obviously prefer to buy chain rings only.

Initial thoughts are as remaining 10 speed shouldn't be a problem.
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As Walter said, it's all about the BCD. The reason that Compact & Standard doubles are different is about BCD - otherwise Compact wouldn't be a thing - you would just change the chainrings on your Standard double. But you can't do that to convert a Standard to a Compact.

At the risk of patronising you, BCD means Bolt Circle Diameter (sometimes referred to as PCD - Pitch Circle Diameter), and this is the diameter of the circle of the chainring bolts. Most Shimano Standard cranksets will have a BCD of 130mm (Campag is usually different of course - often 135, but there are other sizes too that are all "Standard"). The smallest chainring you can fit on a 130 BCD is I think 38, and this wasn't a problem in the old days cos front mechs couldn't handle the step to anything smaller anyway - so if you needed a smaller ring you had to use a triple. But when technology improved and you could change between wider ranges on the front the Compact concept came int being. BUT to accommodate any ring smaller than 38 teeth they had to use a smaller BCD. So this is why Compact chainsets are different - Shimano Compacts use a BCD of I think 110mm.

So to answer your question if you want to change from a Standard double to compact setup you need a new crankset. Doesn't matter whether you use 34 or 36 little ring as they will both be 110BCD on Shimano. Shifters & front mechs should usually work with either, but this is not always the case.

Something you want to check out is the upper range of gears on a Compact setup. You can only go so fast with a 50 big ring & might find yersel spinning out sooner on downhill (I knaa yer like gannin fast like), and also in the big gears there are slightly higher friction losses on a Compact vs Standard.

I have read somewhere that Campag are moving to one common BCD for all their cranksets, so with this arrangement you would be able to just swap chainrings as you like. This seems eminently sensible so I suspect everyone may do this in future.
 
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Al said:
As Walter said, it's all about the BCD. The reason that Compact & Standard doubles are different is about BCD - otherwise Compact wouldn't be a thing - you would just change the chainrings on your Standard double. But you can't do that to convert a Standard to a Compact.

At the risk of patronising you, BCD means Bolt Circle Diameter (sometimes referred to as PCD - Pitch Circle Diameter), and this is the diameter of the circle of the chainring bolts. Most Shimano Standard cranksets will have a BCD of 130mm (Campag is usually different of course - often 135, but there are other sizes too that are all "Standard"). The smallest chainring you can fit on a 130 BCD is I think 38, and this wasn't a problem in the old days cos front mechs couldn't handle the step to anything smaller anyway - so if you needed a smaller ring you had to use a triple. But when technology improved and you could change between wider ranges on the front the Compact concept came int being. BUT to accommodate any ring smaller than 38 teeth they had to use a smaller BCD. So this is why Compact chainsets are different - Shimano Compacts use a BCD of I think 110mm.

So to answer your question if you want to change from a Standard double to compact setup you need a new crankset. Doesn't matter whether you use 34 or 36 little ring as they will both be 110BCD on Shimano. Shifters & front mechs should usually work with either, but this is not always the case.

Something you want to check out is the upper range of gears on a Compact setup. You can only go so fast with a 50 big ring & might find yersel spinning out sooner on downhill (I knaa yer like gannin fast like), and also in the big gears there are slightly higher friction losses on a Compact vs Standard.

I have read somewhere that Campag are moving to one common BCD for all their cranksets, so with this arrangement you would be able to just swap chainrings as you like. This seems eminently sensible so I suspect everyone may do this in future.
Click to expand...

Impossible given my uselessness...

Well the Compact crankset is cheap enough so will just replace whole crankset.
The compact will just be on winter bike when I'm never too bothered about speed( or spinning out)
The 52/36 might be an option for summer bike and I'll have a word with Luke ( Cycleworld) about options and costs etc

If/when back racing I'll certainly keep the 54/42 on TT bike

Ta for reply btw
 
Cee Jay said:
Impossible given my uselessness...

Well the Compact crankset is cheap enough so will just replace whole crankset.
The compact will just be on winter bike when I'm never too bothered about speed( or spinning out)
The 52/36 might be an option for summer bike and I'll have a word with Luke ( Cycleworld) about options and costs etc

If/when back racing I'll certainly keep the 54/42 on TT bike

Ta for reply btw
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Yer reet into this compact malarkey now like!

Where one leads, others follow ;)
 
Oswald Ballbag said:
Yer reet into this compact malarkey now like!

Where one leads, others follow ;)
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Just for winter bike mate....and holidays ;)

only dropping from 53 to 52 on summer bike.
will keep same cassettes..certainly don't need the 32 that was on in majorca

speaking if which. ..........;)
 
Cee Jay said:
Just for winter bike mate....and holidays ;)

only dropping from 53 to 52 on summer bike.
will keep same cassettes..certainly don't need the 32 that was on in majorca

speaking if which. ..........;)
Click to expand...

Aye, aye, aye...whatever.

Crap forecast for weekend. Anyone got any decent rides planned?

Was that a bit contradictory?
 
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