Duane Behrens

The bike is an '84 Raleigh Super Course. The crank is stamped with the Raleigh logo. The existing BCD for that crank is 144 mm. The existing chain rings are 52 x 42. I'd like to change these to something a bit more hill-friendly if I can; a 50 x 34 or even a 53 x 39. But the commonly available chain rings seem to come only in 110 BCD or 130 BCD. Is there a good source out there for 144 BCD chain rings? Thanks in advance. DB

ThermionicScott 

41T is the smallest possible chainring for 144 BCD, and that's pretty rare. You'll probably need to switch to a different crankset or freewheel/cassette to get lower gears...

(FWIW, Vuelta makes chainrings in 144 BCD, and forum member puchfinnland has/had some NOS chainrings kicking around.)

gl98115

You can't.

hueyhoolihan

i've got a nice old 144 BCD crank and i buy new chainrings for it all the time. look on ebay. as stated, there are limits, like on all cranks, on how low you can go though on a chainring directly connected to the spider.

ThermionicScott 

Ooh, good point! With a "tripleizer" chainring, you can attach a granny ring to the now-middle 42T inner chainring. I think pastorbobnlnh has started making those, after other outfits stopped.

https://www.redclovercomponents.com/1...triplizer.html

HillRider

As noted, you already have what is realistically the smallest commonly available chainring (42T) that will fit on a 144 mm BCD. If you want smaller rings, you need a completely different crank. A 130 BCD will take down to 38T and a 110 will take a 33T but 39 and 34 are far more common.

fietsbob

Others have drilled and tapped the crankarms to mount a 3rd chainring , including Campagnolo them selves..

I have a Gippiemme triple (will sell) they made theirs so the 3rd ring an 86bcd
went into the back side of the crank spider, made thicker so hole didn't go through.

I have it set up as a 36 - 52 + a Campag 222. chain guard disc as the outside ring . looks great, too ..

Duane Behrens

Thanks, all. Have disassembled and serviced cranks and bearings but have never replaced them with a different size. If I DO replace them I guess a 110 would be the way to go. Will there be issues I should be aware of? BB length, diameter, threading, etc.? Appreciate your input . . . DB

ThermionicScott 

If the manufacturer of your new crankset is nice enough, they'll provide a recommended BB length, and attachment type. From there, you'd just get the right BB for your frame.

If buying another C&V crankset, a lot of that data is here: https://www.velobase.com/

Duane Behrens

Thanks to all. Just to close this thread out, I found an '84 Centurion Lemans which came with a 110 BCD crank - rare for its day, apparently. That crank came with a 52x40 (not 52x42) crankset. It swapped right out with the Super Course's 52x42 crankset. I then ordered up a single 34t inner chainring from Harris Cyclery for $15. Bolted that onto the 110 BCD. I didn't even have to change the spindle bolt or chain length. A mere adjustment of the front derailleur and I was on my way, climbing these local steep hills like nobody's business.

I offer this up here for any who are considering the same sort of change. I COULD have ordered a new 110 bcd crankset, and probably will when I get going on the Centurion bikes. But for now, I've temporarily saved about $150 with this simple swap. DB

HillRider

110 BCD cranks were not at all rare in the 1980's. SR, Sun Tour and Suguino all made them and they were common on mid to lower cost decent bikes. My '85 Bridgestone 400 came with an SR 110 bcd crank with 52/42 chianrings and with a second set of 74 mm threaded holes for a granny ring that was optional.

Duane Behrens

Good to know. Thanks.

fietsbob

TA makes a 41 tooth chainring, That's as small as will fit on a 144 crank .