Help Shimano DA 7410 chainring question

[Rp]

***NOTE*** Please remove -nospam- from address when replying ***NOTE***

Hello,

I'm running DA 8spd STI and am hunting for a 39T. I know that there are various versions of 7410 53T
rings, marked 'A', 'B', or even no mark I think. My 53 is the B version with the ramps. I need to
know if all of the 39T DA 8spd rings were the same or if they too came in 'A' and 'B' versions. Mine
is marked Shimano SG, B-39. Since the 39 doesn't have ramps did these ever change over the 7410
years? Should I only hunt for a B-39 ring for best shifting or will any 8sp DA 39 be fine?

TIA -rp ***NOTE*** Please remove -nospam- from address when replying ***NOTE***

 

[Sheldon Brown]

A shy person asked:

> I'm running DA 8spd STI and am hunting for a 39T. I know that there are=

> various versions of 7410 53T rings, marked 'A', 'B', or even no mark I think. My 53 is the B
> version with the ramps. I need to know if all of the 39T DA 8spd rings were the same or if they
> too came in 'A' and 'B' versions. Mine is marked Shimano SG, B-39. Since the 39 doesn't have ramps
> did these ever change over the 7410 years? Should I only hunt for=

> a B-39 ring for best shifting or will any 8sp DA 39 be fine?

In Shimano chainrings, "A" designates 39 tooth, "B" designates 42 tooth.

All 39s are "A"s; All 42s are "B"s by definition.

There are two kinds of 53s:

=95"A" type that is intended to be used with a 39 95"B" type, which is intended to be used
=with a 42

If you have poor shifting skills, matching the chainrings by the letters =

will give slightly better shifting, but if you're a reasonably skilled=20 cyclist, it really
doesn't matter.

>***NOTE*** Please remove -nospam- from address when replying ***NOTE***=

No, I don't do that; hope you read the newsgroup.

Sheldon "Only Jumps Through Some Hoops" Brown +---------------------------------------------------+
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http://captainbike.com http://sheldonbrown.com

 

[Meccanico Di Bi]

rp <[email protected]> wrote in message news:<[email protected]>...
> ***NOTE*** Please remove -nospam- from address when replying ***NOTE***
>
> Hello,
>
> I'm running DA 8spd STI and am hunting for a 39T. I know that there are various versions of 7410
> 53T rings, marked 'A', 'B', or even no mark I think. My 53 is the B version with the ramps. I need
> to know if all of the 39T DA 8spd rings were the same or if they too came in 'A' and 'B' versions.
> Mine is marked Shimano SG, B-39. Since the 39 doesn't have ramps did these ever change over the
> 7410 years? Should I only hunt for a B-39 ring for best shifting or will any 8sp DA 39 be fine?
>
> TIA -rp ***NOTE*** Please remove -nospam- from address when replying ***NOTE***

Just bolt on any old 130mm bolt circle diameter 39t c-ring and hit the highway. All those ramps,
bevels, pins and what-not on the big ring are there to help lift the chain from the small to the
big, the small doesn't really need anything special on it for the shifting to be good. --Jim

 

[Qui Si Parla Ca]

sam-<< I'm running DA 8spd STI and am hunting for a 39T. I know that there are various versions of
7410 53T rings, marked 'A', 'B', or even no mark I think. My 53 is the B version with the ramps. I
need to know if all of the 39T DA 8spd rings were the same or if they too came in 'A' and 'B'

Put any 130mm BCD 39 t ring on there-any maker, shimano, TA, Sugino, anything. It'll work just fine.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"