jrupe

I have a Panda Bike Co. road bike that I figure is early '80s. It came with cottered spindle bottom bracket heavy crankset. I am looking to replace it with a square spindle BB. The shell diameter on the bike is 70mm and the original spindle running a double is 144mm. I'd like to run either a single or double from an 86 BCD Apex crank, but I need a new bottom bracket.

Any advice for a 70mm bottom bracket to get some square spindles?

dddd

Check again, the bb shell should be only 68mm in length (not diameter).

Your Asian frame will use an English bottom bracket. Shimano sells UN55 bottom brackets that offer smooth operation and great sealing for like twenty-something dollars.

Length will depend on whether you go double or triple. The original bb spindle had considerable offset but most of the aftermarket Shimano bb's will have symmetrical spindle positioning so might need to be slightly longer than the original bb used with an Apex crankset.

I have a pile of cartridge bb's here so i might first try a 118mm and do a test-fit to see what happens.

jrupe

dddd sorry about that! you're totally right, i meant shell width, not diameter. but regarding the width, my digital caliper had it at a hair over 70mm. I thought this was strange because I read that generally Italian threaded shells were 70mm and English were 68 or 73. I'll post some photos, let me know what you think. And thanks for your help!

3speedslow

Your Panda is much like the BB found on the Sekine frames. Some resize the BB, reuse the original crankset or try and make a 73 work.

Whole frame pic?

jrupe

jrupe

Was super stoked to pick up this Panda, the decal and orange got me. Panda is known for their early BMX bikes apparently. If anyone know Randell Kim and can put me in touch, apparently he is really nice and loves to chat about his old designs. If anyone has any info or idea about year, let me know!

jrupe

The components may help date it.

I'm wondering if the Suntour Perfect 6 speed I have will fit on the hub this Shimano is on. I believe it will but thought I'd ask. Still waiting on the right lockring tool to check.

Also wondering, if I use a 34T sprocket on the Perfect, will this Shimano Eagle handle it? Looks like at least a medium cage so think so, but can't tell.

Still wondering which size Bottom Bracket to get, I'd like to run it 1X like a beach cruiser, but option for 2X would be nice I guess.

Thanks again for any and all tips and advice!

John

T-Mar

Those are 1st generation Eagle and Thunderbird derailleurs, which make it pre-1977. However, the freewheel makes it pre 1976 and post 1972. So, it should be circa 1973-1975.

The SunTour freewheel will fit on the hub but unless it's an Ultra-6 unit, you may have to install a longer axle and cold set the rear triangle. The Eagle will handles a 34T rear cog but with the short cage length you'll have to watch the differential on your front chainrings

jrupe

Thanks T-Mar, '73 to '75 it is, awesome!

If I go with a single 28T ring up front, I should be fine, right?

The perfect is not an ultra, I'm pretty sure. Originally a 14-30. Adding a Pro-Compe 34, kicking 19 off spline, removing 16 and adding a New Winner 18 threaded.

T-Mar

If you're running a 28T single up front, you should be fine. You'll just have to shorten the chain appropriately.

A standard 6 will fit on the hub and may even fit into the frame without issues. However, once you install the chain and try to shift there may be interference from the seat stay. .

jrupe

Good to know about the seat stay. Would the bottom bracket I choose have anything to do with moving the chainline a bit further out?

If it is indeed a 70mm shell width, does it have to be Italian threading? Shimano seems to think it must be.

Would there be much difference between 113 and 118, would 118 better allow the possibility of a double chainring down the line?

https://www.performancebike.com/shim...iABEgKs0PD_BwE

https://www.benscycle.com/Shimano-UN...iABEgLGRvD_BwE

Thanks!

Lascauxcaveman 

I've stretched out a few RDs well past their official capacity, so I'm gong to say ... maybe? depends on how long that hanger is, chain length and the jump between the big and small chainring, if you go for two up front.

T-Mar

As previously mentioned by 3speedslow, it could very well be English threaded. Some Japanese manufacturers, such as Sekine used 70mm shells with 68mm axles due to very thick bottom bracket cups. The easiest way to check if it is English or Italian threaded is to verify the thread direction of the existing fixed cup. English will be left hand thread, while Italian will be right hand thread.

Unfortunately, establishing proper chainline when changing bottom brackets and cranksets, is often matter of trial and error.

T-Mar

In this case, it's not exceeding the maximum large cog size, which was stated as being 34T.

steve sumner

the edge of your BB shell shows some paint telling me it was never faced
a few spins with a facing tool can take the width from 70 to 68 in seconds

3speedslow

This is what I would suggest. IF, you have a friendly and competent LBS!

BTW, that headbadge is the Kung fu master!

jrupe

3speedslow and steve summer thanks for the advice! I get what facing is and i know where the metal workers are near the dealerships and mechanic shops in the Canal. But can you fill me in on what an LBS is?

And totally! the Panda headbadge is very Kung Fu and definitely sold me on the bike!

Thanks again

dedhed

LBS = Local Bike Shop

jrupe

dope! thanks dedhed