Chainring Help

needhelp said:

Hi, I have an old Peugeot road bike with sachs hubs, cassete and rear derailer.
Because of this I am assumenu that it also has sachs cranks and chainrings.

It has a 7 speed cassete.

My question is at the moment the chainrings are 42/52 and I am looking at running a 39 to help on the hills. Will any chainrings fit or will only specific ones fit and if so which ones.

The chainring has a 5 bolt pattern if that helps.

Thanks in advance.

Almost certain that a 130mm bcd (bolt circle diameter) chainring will fit. This is the most common size for double chainring cranksets and is the size for Shimano, FSA, and common non-Campagnolo chainrings.

To be sure, measure the distance between two consecutive chain ring bolt holes, if it is 76.4 mm, then the bcd is 130mm. Current compact doubles and road triples (outer ring) use 110mm bcd chainrings. Some touring doubles used 110mm. If so, the distance between two chainring bolts is 64.7mm.

The fact that the bike is French could make it something less common though, so it is best to measure.

See this link for more information:

http://sheldonbrown.com/harris/chainrings.html

needhelp said:

Hi, I have an old Peugeot road bike with sachs hubs, cassete and rear derailer.
Because of this I am assumenu that it also has sachs cranks and chainrings.

It has a 7 speed cassete.

My question is at the moment the chainrings are 42/52 and I am looking at running a 39 to help on the hills. Will any chainrings fit or will only specific ones fit and if so which ones.

The chainring has a 5 bolt pattern if that helps.

Thanks in advance.

Have you considered changing the cassette to get the lower ratio's required to get up the hill? Some of the new mtb cassetts still run 7sp and if the hub splines match and the range of the rear deraileur can take the larger gear this may be the easier/ cheaper option.