crown race compatibility question DA 7710

[Rebel_Biker]

I need a new crown race for a 7710 sealed cartridge HS. Will the below work?

ACS crown race (27.0mm) for 1" integrated headset

[oldpotatoe]

I need a new crown race for a 7710 sealed cartridge HS. Will the below work?

ACS crown race (27.0mm) for 1" integrated headset

JIS(27mm) fork crown race? 27mm vice 26.4mm firm crown race seat?

[Rebel_Biker]

JIS(27mm) fork crown race? 27mm vice 26.4mm firm crown race seat?

thank you oldpotatoe

are you telling me it won't work? Or should I confirm that it has a JIS 27mm diameter?

[ultraman6970]

27.0 is jis, the problem you might find is another one.

ACS has a 1 1/8 to 1 inch conversion headset, to use a 1inch fork in a 1 1/8 integrated headset frame... I got one of those for an experiment and the crownrace is 27 and will fit a 45 degrees bearing (1 1/8)... the bearing in the shimano headset you have in similar to that just in case.

I have the 600 threaded version of the headset you have just in case, the thing is that I tried the crown race of the ACS with the bottom cup and bearing of the 600 and did not match, the OD of the race fits but the shape of the race is wrong, it seats too deep (if i remember right) into the shimano cup. I have the parts and take some pictures for you if you want.

No idea what crown race is that and which ACS headset fits, w/o that is hard to even think it will work, if it match the conversion headset I have then it might not work.

The other problem is that shimano bearing, I'm not 100% if its a 45/45 or a cane creek spec. I do know the outside angle is 45 degrees tho... the internal angle have no idea, probably is 30 degrees (or is 33?) because all the campy specs crownraces I have toyed with don't fit right either.

[oldpotatoe]

thank you oldpotatoe

are you telling me it won't work? Or should I confirm that it has a JIS 27mm diameter?

27mm refers to the diameter of fork where the fork crown race sits. 27mm generally low end forks. Besides not really conforming to the lower bearing of the headset, the inside diameter of the fork crown race may be too big for the fork.

What fork?

Cart bearing shimano headset fork crown races pretty easy to find.

[ultraman6970]

This is the headset im talking about... the crown race will fit the shimano cup but the fit of the crown race in the shimano bearing is weird, wrong shape.

http://www.bikesonline.com/acs-main-drive-headset-integrated-1-1-8-converts-to-1-steerer-black.htm

I'm not sure about the OD of the 1 inch crown race you are talking about, it might be smaller than the one I'm talking about. Always you can send an email and ask the manufacturer or the seller, IMO it should be smaller OD. And the other detail is the angle of the race too.

[Rebel_Biker]

27mm refers to the diameter of fork where the fork crown race sits. 27mm generally low end forks. Besides not really conforming to the lower bearing of the headset, the inside diameter of the fork crown race may be too big for the fork.

What fork?

Cart bearing shimano headset fork crown races pretty easy to find.

It is going on a Serotta F1 threaded fork. I have the old crown race, it has an OD of 41.22mm.

It bent on the pull out. I did not have the crown race puller arms tight enough around the race.

[ultraman6970]

Now I get what potato was saying... are you sure the fork is jis and not iso?

Looks the same than this one and the one in the headset i have...

http://www.jensonusa.com/Crown-Races/Shimano-Headset-Crown-Race

ps: when you remove them use a piece of wood not a screwdriver and tap around.

[oldpotatoe]

It is going on a Serotta F1 threaded fork. I have the old crown race, it has an OD of 41.22mm.

It bent on the pull out. I did not have the crown race puller arms tight enough around the race.

What you need is the fork crown race from either ultegra or DuraAce cartridge bearing, 1 inch, headset. 26.4mm diameter, not 27mm(Interior diameter).

Ultegra is steel and black, DA is aluminum and silver, bearings are the same.

Might be easier to buy a headset. 1 inch version of XT the same. IF all fails, just gently massage that FCR back into shape.

[Rebel_Biker]

What you need is the fork crown race from either ultegra or DuraAce cartridge bearing, 1 inch, headset. 26.4mm diameter, not 27mm(Interior diameter).

Ultegra is steel and black, DA is aluminum and silver, bearings are the same.

Might be easier to buy a headset. 1 inch version of XT the same. IF all fails, just gently massage that FCR back into shape.

thanks oldpotatoe, always an incredible resource

I have a shimano account - they don't list 7710 small parts but they probably have the XT

[8aaron8]

I am pretty sure I have a 27.0 dura ace crown race. One of my DA headsets came with a 27.0 race, if I can find it it's your, but it sounds like you need a 26.4 so it might not be useful. Let me know.

[oldpotatoe]

thanks oldpotatoe, always an incredible resource

I have a shimano account - they don't list 7710 small parts but they probably have the XT

7710 was pista stuff(or 25th anniversary stuff??) but 7410 and 6500 FCR part numbers are

DA-7870411

ultegra-Y78704000

[Rebel_Biker]

7710 was pista stuff but 7410 and 6500 FCR part numbers are

DA-7870411

ultegra-Y78704000

thank you

shimano is not stocking them but I will scour the internet for one

[commonguy001]

If the 105 level crown race was the same type and would work I'm pretty sure I have one in my tool box that's been in there for 10+ years. I probably have the whole lower portion of the headset if it matters...

[oldpotatoe]

If the 105 level crown race was the same type and would work I'm pretty sure I have one in my tool box that's been in there for 10+ years. I probably have the whole lower portion of the headset if it matters...

Yep if cart bearing, same FCR.

[commonguy001]

Yep if cart bearing, same FCR.

I'll take a look tonight

Rebel_Biker if it'll work you're more than welcome to it as I'll never use it

[Rebel_Biker]

I'll take a look tonight

Rebel_Biker if it'll work you're more than welcome to it as I'll never use it

thank you

thank you all for the help

I popped this off a Serotta F1. CSI frame and fork are going to Billy Mac for a re-spray.