Chain wheel replacement

Porcia

Active Member
Location
Ashford Kent
SO I am looking to change the front chain wheels from 53/ 43 to 50 /38 as I is getting long in the tooth and hills a getting harder to climb. Every thing starts out fine measure the PCB or BCD 130mm not a problem but the strange flat headed Allen bolts holding the ring's to the crank are what look like imperial sizes, had to get my vernier and Zeus table out, turns out I need a 3/16 Allen key to remove them who'd have thought.
 

Cycleops

Guru
Location
Accra, Ghana
You don't say what pattern the spider is so I don't know how easy/difficult it might be to obtain one in the size you want. You might have to buy a new unit. If you need lower gears might be easier and cheaper to change your rear cassette instead if your RD will handle it.
 
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Ajax Bay

Guru
Location
East Devon
I would just swap out the 43t for a 38t first. Or even a 36t. The FD will handle a 16t difference (and would probably manage 17) - but the RD capacity may not be sufficient (depends on the freewheel block range). Having a 53/43 implies this is a vintage chainset on a bike to be used in flat country. What make of chainset, FD and RD?
 
OP
OP
Porcia

Porcia

Active Member
Location
Ashford Kent
OK problem solved it look like the chain wheel 52 teeth I miscounted, made in USA stamped on the back might have given it away and the reason for the 3/16 head Allen bolts. The Bike is a bit of a bitsa, 2012 Cannondale frame, Shimano 105 11-28 and think the crank set was from a bike jumble. The new chain wheels 50 /38 have been fitted, had to get new metric bolts to fit them.
 
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