Chainring and freewheel compatibility

[Vintage Trek]

I have an old Trek 560 that I am rebuilding bit by bit. I am thinking of replacing the original triple Biopace chainrings, which are still in great shape, with a new triple Shimano Ultegra set (52/42/30). These Ultegra chainrings say that they are meant for 9 speeds, but I have a new 7 speed Shimano freewheel (which replaced the original Helocomatic freewheel). Will these chainrings work with a 7 speed freewheel even though they are intended to be used with 9 speeds?

 

[alfeng]

I have an old Trek 560 that I am rebuilding bit by bit. I am thinking of replacing the original triple Biopace chainrings, which are still in great shape, with a new triple Shimano Ultegra set (52/42/30). These Ultegra chainrings say that they are meant for 9 speeds, but I have a new 7 speed Shimano freewheel (which replaced the original Helocomatic freewheel). Will these chainrings work with a 7 speed freewheel even though they are intended to be used with 9 speeds?

Yes, you can use the 9-speed Ultegra crank with your 7-speed 'stuff' ...

BTW. If you are getting your crank through a bike shop OR mail order then you MAY want to order a crank with 52/39/30 chainrings.

FYI. You could just replace the Biopace chainrings with ROUND chainrings ... I would just change the outer & middle rings and leave the granny as a Biopace AND only change the granny if you find that the shifting is dodgy (the smaller, 39t middle ring should expedite shifting between the middle & Biopace granny) ... you will just have to lower the front derailleur to a new height which is appropriate for the outer chainring.

 

[Vintage Trek]

Thanks for your help. I'll see what I can find out there.

 

[Peter@vecchios]

I have an old Trek 560 that I am rebuilding bit by bit. I am thinking of replacing the original triple Biopace chainrings, which are still in great shape, with a new triple Shimano Ultegra set (52/42/30). These Ultegra chainrings say that they are meant for 9 speeds, but I have a new 7 speed Shimano freewheel (which replaced the original Helocomatic freewheel). Will these chainrings work with a 7 speed freewheel even though they are intended to be used with 9 speeds?

Yep, just install and ride. As for a 52/39/30..those came out with the advent of 10s, but that will work also. However, if ya do get the 52/39/30 option, you will need the deep cage FD(specific for a 52/39/30, like 6603) or getting the chain off the 39 will be 'iffy'.
However, I think a 42 middle, on a well set up triple, if best since on a well set up triple, you get full range of the rear cassette in the middle, I think the 39 is a wee bit to small. IMO, of course as gearing is personal.

 

[alfeng]

Thanks for your help. I'll see what I can find out there.

Remember that eBay can be a source for new-or-used chainrings ...

AND, if-and-when you do decide that you want a new crankset & BB, then you can probably find what you want on eBay.

 

[alfeng]

Yep, just install and ride. As for a 52/39/30..those came out with the advent of 10s, but that will work also. However, if ya do get the 52/39/30 option, you will need the deep cage FD(specific for a 52/39/30, like 6603) or getting the chain off the 39 will be 'iffy'.
However, I think a 42 middle, on a well set up triple, if best since on a well set up triple, you get full range of the rear cassette in the middle, I think the 39 is a wee bit to small. IMO, of course as gearing is personal.

FWIW. The reason I suggested a 39t, in addition to making shifting onto a Biopace granny easier (in theory), is because it is probably slightly easier to find a set of 52/39 or 53/39 chainrings than a set of 52/42 ...

AND, I would rather treat a granny as a bail-out granny rather than worry about the middle chainring optimizing the usable intermediate gearing ... but, I'm not touring.