Crankset Question

[mark171penn]

Hi, I'm trying to replace chainwheel, chain and freewheel. They all are very worn. I can't use the Bolt Circle Diameter method for my 4-arm crankset because it has 2 rivets on one arm and 1 rivet on the next arm. It's a Suntour SR. I read that on that kind of crankset I can't replace a single chainring--that the whole crankset has to be replaced. As for the chain, I guess I can just use a 3/32" 7-speed chain since the freewheel is a 7 speed. And I guess I can just get another 7 speed freewheel. Am I correct about what chain and freewheel to buy? And how do I know what crankset will fit? Will the ones at these urls work? http://www.amazon.com/Shimano-FC-M131-Tourney-Crankset-48-38-28/dp/B003ZMDJW6/

http://www.amazon.com/Shimano-FC-M171-Altus-Crankset-170-mm/dp/B003ZMFNX4/

http://www.amazon.com/Shimano-M361-Hybrid-Crankset-Black/dp/B004V2996E/

Thank you.

[RBurrelli]

Hard to answer because we don't know anything about the bike you are trying to put these on. Can you supply more complete information?

[nfmisso]

Hi Mark;

Any of the cranksets will work okay; the cheapest will last as long or longer than the others.

I would replace the BB at the same time.

http://www.amazon.com/Shimano-Square-Bottom-Bracket-68x110mm/dp/B005DTIG9U/

For the M131; Shimano recommends 123mm BB; but I found on my GT http://forums.bikeride.com/thread-3167.html that 113mm would suit me much better. The 123 put the chainwheels in a position such that the 28-11 combination works with no chain rub, but the 48-30 and even the 38-30 have too extreme a chain angle. I don't care if the 28 at the front can't be used with have the cogs at the back, but I want to be able to use the larger cogs at the back with the larger rings at the front.

Freewheels: I have had two bad Shimano freewheels, and have switched to Sunrace 13-25 on both of my bikes with freewheels. I plan to try an IRD http://www.amazon.com/FREEWHEEL-7SP-DEFIANT-13-24T-NICKEL/dp/B003PXYV1S/ next time, but the cost is holding me back. The IRD's ratio are better balanced: 13/14/15/17/19/21/24 compared to Sunrace's: 13/15/17/19/21/23/25 which results in too big a jumps at the high end, and too little a jumps at the low end.

[mark171penn]

(03-20-2013, 04:08 PM)nfmisso Wrote:  Hi Mark;

Any of the cranksets will work okay; the cheapest will last as long or longer than the others.

I would replace the BB at the same time.

http://www.amazon.com/Shimano-Square-Bottom-Bracket-68x110mm/dp/B005DTIG9U/

For the M131; Shimano recommends 123mm BB; but I found on my GT http://forums.bikeride.com/thread-3167.html that 113mm would suit me much better. The 123 put the chainwheels in a position such that the 28-11 combination works with no chain rub, but the 48-30 and even the 38-30 have too extreme a chain angle. I don't care if the 28 at the front can't be used with have the cogs at the back, but I want to be able to use the larger cogs at the back with the larger rings at the front.

Freewheels: I have had two bad Shimano freewheels, and have switched to Sunrace 13-25 on both of my bikes with freewheels. I plan to try an IRD http://www.amazon.com/FREEWHEEL-7SP-DEFIANT-13-24T-NICKEL/dp/B003PXYV1S/ next time, but the cost is holding me back. The IRD's ratio are better balanced: 13/14/15/17/19/21/24 compared to Sunrace's: 13/15/17/19/21/23/25 which results in too big a jumps at the high end, and too little a jumps at the low end.

Thank you for your help.
Also, as for the chain, the 3/32" for a 7-speed freewheel will work?
Mark

[nfmisso]

Hi Mark

Any 7 or 8 speed chain will work. The Bell brand chain at Wal-Mart is fine. I have a couple of those on my bikes, as well as SRAM, Shimano and KMC.

[mark171penn]

(03-23-2013, 07:04 PM)nfmisso Wrote:  Hi Mark

Any 7 or 8 speed chain will work. The Bell brand chain at Wal-Mart is fine. I have a couple of those on my bikes, as well as SRAM, Shimano and KMC.

Thank you Nigel,
Mark