Bicycle Mechanics - Bridgestone Headtubes/Headsets -- JIS or ISO???

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kirke
05-22-09, 08:09 AM
Just wondering if anyone knows if old Bridgestones like the RB-1/RB-2 require an ISO or a JIS headset?
Thanks!

merckx_rider
05-22-09, 08:33 AM
Have any pics?
dobber
05-22-09, 08:54 AM
I'd be willing to wager ISO.

jgedwa
05-22-09, 08:57 AM
Oh, I would bet good money on JIS.

jim
vredstein
05-22-09, 08:57 AM
The inside diameter of my 1989 MB6 is 29.84 mm. The fork's crown takes a 26.4 mm race.
HillRider
05-22-09, 09:00 AM
My '85 Bridgestone 400 came with a JIS crown race and I had the LBS mill it down to ISO size when I replaced the headset. The ISO cups seemed to fit properly in the headtube so the OEM may have been a mixed size.

By the time the RB series came along I believe they were all ISO.
kirke
05-22-09, 10:10 AM
Yes, the bike in particular is an early 90s RB-2, one of the Grant Peterson designed ones. I would guess its ISO but wanted to ask. Dont have the bike yet, or else I would measure.
Wanted to order a new headset while I am waiting for the bike.
HillRider
05-22-09, 10:21 AM
Wanted to order a new headset while I am waiting for the bike.
I'd wait until you have the bike. The delay can't be that much and not nearly as long as getting the wrong headet and having to replace it
jgedwa
05-22-09, 11:44 AM
Yeah, the bike gods are cruel. Whatever size you order will invariably be wrong. Do not temp the gods. And if you get all fancy and order both, then you are sure to find a cracked braze when you look again.

jim
kirke
05-22-09, 03:54 PM
Yeah...y'all are right. The peer pressure convinces me to wait...
dobber
05-22-09, 07:54 PM
Oh, I would bet good money on JIS.

jim

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