48T To 42T Chainset

[Colin0912]

hello i was wondering if some one could tell me a 42T set would be ok to use with a 6 speed

Many Thanks
Colin

 

[Poacher]

Should be perfectly OK. You might need to take 2 or 4 links out of the chain to maintain a similar tension, but try it first without doing so, in case your derailleur can take up the slack.

 

[Colin0912]

Thank you all for getting back to me so quickly i been searchign for some time for a general cycling forum and its been pain i think i stay here thanks for the help

 

[mcshroom]

Do check what sort of crank/bottom bracket you currently have. I'd bet you have a square taper (looks square where the crank joins) but do check to make sure any new chain-set fits

Oh and to the forum

 

[Colin0912]

Thank you yes i currently have a square taper in place the front chainset will be 42T/34T/24T and changing rear free cassete to a different ratio also of

• 1st Gear - 34 Teeth
• 2nd Gear - 24 Teeth
• 3rd Gear - 21 Teeth
• 4th Gear - 18 Teeth
• 5th Gear - 16 Teeth
• 6th Gear - 14 Teeth

sorry for way its come out copied of the website

 

[RecordAceFromNew]

Hi I am unsure the reason why you want to go to a 42T, but you will find it will lower the top (highest) gear significantly, to under 80 inches with the 14T cog of your freewheel. It is fine if you tend not to go quicker than 20mph and/or always freewheel downhill. Most people have a high gear of 90 inches (like what you have with a 48T) or more.

As others have said you might need to shorten the chain, and the front shift will work better if you move the front mech down the seat tube by 12mm (assuming it is perfectly set currently, worth checking if the seat tube has the room for the front mech to move down).

The most important thing about changing chainset is not just to ensure it is square tapered (if the bottom bracket is), but also to maintain the chainline by ensuring the new chainset delivers a very similar if not exactly the same chainline with the old bottom bracket (assuming you are not getting a new bottom bracket). If the chainline is out you are likely to have difficulties in getting the front mech to work with the new chainset.

 

[Colin0912]

Hi I am unsure the reason why you want to go to a 42T, but you will find it will lower the top (highest) gear significantly, to under 80 inches with the 14T cog of your freewheel. It is fine if you tend not to go quicker than 20mph and/or always freewheel downhill. Most people have a high gear of 90 inches (like what you have with a 48T) or more.

As others have said you might need to shorten the chain, and the front shift will work better if you move the front mech down the seat tube by 12mm (assuming it is perfectly set currently, worth checking if the seat tube has the room for the front mech to move down).

The most important thing about changing chainset is not just to ensure it is square tapered (if the bottom bracket is), but also to maintain the chainline by ensuring the new chainset delivers a very similar if not exactly the same chainline with the old bottom bracket (assuming you are not getting a new bottom bracket). If the chainline is out you are likely to have difficulties in getting the front mech to work with the new chainset.

Ok Thank you for that explanation so would be better to get a lower range rear cassette and reason going down for a 42T if im having trouble locating a 48T replacement plus previous owner replaced with the wrong front mech

If i changed things Front mech replacement and went up to 52T would that be better ??

Also to add a note i Also drag a bike trailer alot with loads up to 100KG so a high Tooth ratio would be better surely?

 

[RecordAceFromNew]

Ok Thank you for that explanation so would be better to get a lower range rear cassette and reason going down for a 42T if im having trouble locating a 48T replacement plus previous owner replaced with the wrong front mech

If i changed things Front mech replacement and went up to 52T would that be better ??

Also to add a note i Also drag a bike trailer alot with loads up to 100KG so a high Tooth ratio would be better surely?

I am afraid 34T is as large a freewheel cog would go usually. For freehubs that take cassettes 36T is generally the maximum size currently, and usually only for 9+ speed.

If you carry/pull a lot of weight then you do need a very low gear, meaning having a small smallest chain ring in front is important. The issue is how to achieve that, and there are different possibilities. Unless your current gearing doesn't let you go fast enough I am not sure if a chainset going up to 52T will suit you.

Perhaps if you could provide the make/model/spec of your current chainset, front mech and explain what is wrong with the current chainset/front mech, if any, then potential options can be identified? For example I am pretty sure 48T chain rings or chainsets are available.

 

[Colin0912]

I am afraid 34T is as large a freewheel cog would go usually. For freehubs that take cassettes 36T is generally the maximum size currently, and usually only for 9+ speed.

If you carry/pull a lot of weight then you do need a very low gear, meaning having a small smallest chain ring in front is important. The issue is how to achieve that, and there are different possibilities. Unless your current gearing doesn't let you go fast enough I am not sure if a chainset going up to 52T will suit you.

Perhaps if you could provide the make/model/spec of your current chainset, front mech and explain what is wrong with the current chainset/front mech, if any, then potential options can be identified? For example I am pretty sure 48T chain rings or chainsets are available.

Hello i started another topic https://www.cyclechat.net/ here the link chat in there as more on where this is going