Can you fit a 34t chainring on a DA7700 crankset?

[Saxon]

Hey everyone, anybody know if I can transform my 39t 7700 crank into a compact? Not sure if a modern 34t ring would work with that crank.

Thanks much,
Rich

[FlashUNC]

No. Don't think they came in a 110 BCD. But at 135, smallest ring you're getting is a 39.

[AngryScientist]

nope. they are 130 BCD. some 38's will fit. that's the smallest you can go.

[texbike]

Yeah, 7700 would have a 130 BCD. A 39T would be the smallest?

Edit - Whoops! Angry beat me to the punch...

Texbike

[djg21]

Originally Posted by Saxon

Hey everyone, anybody know if I can transform my 39t 7700 crank into a compact? Not sure if a modern 34t ring would work with that crank.

Thanks much,
Rich

No. It’s a 130 bcd. You need a 110 bcd to use a 34t ring (or anything smaller than a 38t).

[Bostic]

38 tooth is the smallest for the 130mm BCD. I put a Sugino or FSA on one several years ago.

[Saxon]

Thanks very much for the help all!

Rich

[Ti Designs]

No, but there was a 7700 56/44 chainring set made.

[cachagua]

WAIIIIT!! You can do this, if you're willing to go triple: here is a pair of chainrings that adds a 74mm BCD ring to the inside -- this particular one is a 29t but of course you can substitute any other size.

You got to think about clearance, BB spindle length, chainline, front drlr and shifter, and in view of those considerations it may not be worth it to you. But it's possible.

[oldpotatoe]

Originally Posted by Ti Designs

No, but there was a 7700 56/44 chainring set made.

HA! POTD( if you follow tidesigns posts....

[Mark McM]

Originally Posted by Ti Designs

No, but there was a 7700 56/44 chainring set made.

Well, you have to keep in mind why this chainring set was made. When these chainrings are used on a bike with 650c wheels, the final drive ratio (or "development" as the Europeans like to call it) becomes equivalent to a bike with 700c wheels that have a "traditional" 53/42 chainring set.

[bigbill]

I use a 7410 crankset on my cross bike with a 38/44. At one time there was rumor of a 37 but it required filing of the spider to keep it from interfering with the chain sitting on the chainring. The 38 works well enough.

[cnighbor1]

Originally Posted by Saxon

Hey everyone, anybody know if I can transform my 39t 7700 crank into a compact? Not sure if a modern 34t ring would work with that crank.

Thanks much,
Rich

But that crankset can be converted to a triple setup using DA two inner rings 39t and a 30t Need longer DA BB and longer DA RD cage
I have done it three times

[smead]

Originally Posted by cnighbor1

But that crankset can be converted to a triple setup using DA two inner rings 39t and a 30t Need longer DA BB and longer DA RD cage
I have done it three times

Although I am not positive about this, I recall that the 7703 triple crank arms were a bit different to accommodate the special 39 ring. I thought they didn't have a slot/tab on the inside to accommodate the special 39T ring with the extensions to bolt on the 30T granny.

[Ti Designs]

Originally Posted by Mark McM

Well, you have to keep in mind why this chainring set was made.

Florida...