Desperado

I have an older Asian bike (Kabuki made by Bridgestone), with a sguare taper crank, which I can no longer buy chainrings for, just inspected and lubed the BB, looks like new, I know campy uses its own taper on its BB's, but are the rest ( this is probably SR presently on the bike) using the same taper??... I would like to replace the crankset to something that there are chainrings available for, (need lower gearing) but, would like to keep my present BB, to simplify things just a little. Thanks in advance for any opinions on this.

concernicus

are you asking if there are square taper cranksets available for purchase? if so, then yes

rollsroyce

Are you sure you can't find chainrings for the cranks that are on there now? Do you know what the bolt circle diameter is? If you can find out or measure what your bcd is, we can maybe help you find a chainring...

see the info about measuring bcd on this page:
https://www.sheldonbrown.com/gloss_bo-z.html

Desperado

What I am asking is, if I buy......say a Sugino xd crankset, or some other newer crankset, will the taper on the BB match the taper on the newer cranksets?, maybe I'm just gun shy, but it seems like every part is different in some way, Englis threads, Italian threads, clockwise, counterclokwise, etc etc. So iI would like to upgrade the crankset but keep my present BB if possible. Thanks

genericbikedude

You need cranks with JIS taper, as opposed to Campy (and some others) that used ISO taper. The difference is teeny though, only making a minor difference in chainline and minor difference in lifespan.

Most old bikes take a longer bb than most modern cranks use. Try to find a chainring for your bike. I'd bet dooars to donuts that it is possible

Desperado

Yeah, pretty sure the BCD is 122mm, and it would be tough to put anything smaller than the 36 tooth small ring that is presently on there, the bolt pattern diameter is too large to allow a smaller ring to be attached, at least thats the way it looks to a rookie like me, maybe I'm wrong..... thanks for the help, I can use all I can Get.

ridesoldtrek

There were two styles of axles (spindles) used for cotterless cranks in that era: Type 1 used bolts (with a washer) that screwed into a tapped hole in the ends of the spindle, Type 2 had studs on the ends and used a nut with integral serrated washer. Type 1 axles have a taper of about 2 degrees, but Type 2 can be either 2 degree or 3 degree. You need to use the right type of crank for your spindle. Most of the Type 2 spindles were used with cranks where the right arm was swaged to the spider, vs. a one piece forged assembly. I believe there were some forged cranks that used Type 2, I'm not sure of that though.

The other thing you will find could be a problem with changeout is the chainline and interference of the inner chainring with the chainstay. I have an SR Apex crank that I tried to mount on my Sugino bottom bracket, and it would not work on my frame - the inner chainring hit the chainstay. On the SR Apex that I have, the offset between the inner chainring and the square mounting hole was much greater than the Sugino crank - so the SR would require a longer spindle.

These are murky waters, having spent the last week or two researching the very same issue. Make sure before you buy something that it will really work. Measure the spindle, every dimension you can, and check out the resources on Sheldon Brown's website. It is not complete by any means, but it is a good start. Your spindle should have some markings in the center which will give you some more information to work with.

Good Luck.

Paul

ridesoldtrek

I've got some good resources I could share with you, send me an email.

Desperado

Thanks Paul, mine is the type that uses the bolt and washer, and the crankarm and chainring mount are a forged unit, figures, the markings are on the spindle inside the bearings, should have taken note of that when I had it apart for cleaning, this compatability thing is amazing, I always thought bicycles were simple
thankfully there is a vast resource of knowledge on this forum,..... I thought of buying a new touring bike, sure would be simpler, but hey. there is no challenge in that............ I'll just keep fixing this one 'till its broken

ridesoldtrek

It would probably be simplest to buy an entire new crank and BB. A decent BB is only about $40, compared to the crank which will be more, and you can get the right assembly much quicker. Finding stuff that will match correctly can be a real pain.

Desperado

Will do, after I get a little more info off that spindle and do some more measuring, thanks again

TallRider

I use an SR Apex crank, with 118mm bolt-center diameter, on my commuting bike. It's mounted on a modern sealed BB. But it sounds like you're looking to go the other way - use a newish square-taper crank with your current bottom bracket. Two things on this.
(1) it's better to buy the bottom bracket in support of the crank. That is, don't buy a crank just b/c it'll work with your old bottom bracket.
(2) old bottom brackets like yours are probably long (122mm spindles or longer), while most newer square-taper cranks are designed to work with shorter (107mm, 113mm, etc.) bottom bracket spindles.

If you want a triple crank with square-taper BB, one of the nicest is the Sugino XD. Especially if you want a triple crank (for which you'll need a longer-cage rear derailler as well; I'm assuming your bike currently has a short-cage rear derailler). XD2 goes with a 107mm bottom bracket for correct chainline on 130mm road hubs. On your older bike, the rear hub is narrower, but this will get you close enough for chainline.

If you want a double-crank, there are tons out there on eBay, nice used ones from the late 80's and early 90's.

CHenry

Shimano square-taper sealed cartridge BBs are dirt cheap these days, something like $18 from Nashbar. If you are replacing the crank with a Sugino, buy a new bottom bracket as well.

TallRider

I've got a couple diff Square taper triple cranks sitting around, both 175mm crankarms, and both with their own bottom brackets. 53/42/30 Campy, and a Sugino XD in 48/36/26. Email me (my address is my last name - so, the non-Tim part of my username - at unc dot edu) if you're interested. You could also get something older off of eBay, like an early-90's mountain bike crank.

Desperado

Tim, thanks for the help. I just bought a Sugino XD 48/36/26 used with BB and a front derrailluer on E-Bay,
47.00, when I receive it I'll have a better grasp on what it will take to make everything work together, the included BB will most likely not fit the bike, but it came with the crankset, and will help me understand what I'll need, Will let you guys know how it all turns out, this is one of the best sites on the whole internet, no B.S. just honest people helping were they can, wow this is wonderfull!!

TallRider

The included BB should fit if the bottom bracket is English threaded, which is the case with all old (circa 1980) Japanese bikes that I've seen. 1.37" * 24 threads per inch. You'll just need a tool to install a modern cartridge BB - this thing:
https://www.parktool.com/products/det...5&item=BBT%2D2
Also, if the bottom bracket that comes with the crank is 113mm (ideal for use on mountain bikes), you'll want to replace it with a 107mm BB for proper chainline on a road bike. Well, at least if it's an XD2 (the XD600 apparently takes a slightly wider BB).
-
Thanks for the good words. The mechanics forum here on bikeforums is very much as you describe. Some others, not as much.

ridesoldtrek

This may be the case with an SR, but my Sugino Mighty Tour (kind of a rare bird, like the Mighty Comp but with 110 BCD) which I bought in 1977, has a 113 mm spindle. This works very well on both of my old Treks, 1977 and 1983, but the same BB won't take the inner chainring on the SR Apex. Tim, this is a different version of the Apex than yours, having looked at your pictures. My Apex is forged.

Desperado, if you are interested in the BB/chainring/crank info I have, email me at paulj@relres.com.

TallRider

Yeah, my Apex crank is a double. The crankarms are, however, forged. I think the spider is forged too, but it is seperate.

Desperado

thanks again guys for the help, I got the crankset and used BB today, took out the old BB, and amazingly the sealed unit fit perfectly, and even the chain line looks good, will need to shorten the chain a bit, and might not be able to shift into big/big, but wouldn't do that anyway, the sealed BB I have needs new bearings, will check with the local bearing place to see if they have them, if not the whole unit is only about $20.00 fron Nashbar, should have plenty low gearing now, can't wait for this damn snow to melt, so I can see how it all works.

TallRider

Btw, Desp., are you in Cleveland? I lived there for awhile after college.

silversmith

The mechanics and the framebuilders forums are great.

Less snobs among the wrenches

TallRider

Yup.

HillRider

The Suguino should require the same JIS taper your old SR did so that is no problem. However, your current bottom bracket axle length may be wrong for the new crank. If too short, the chainrings won't clear the chainstays and if too long, the chainline will be bad.

Whops, I should read the entire thread before replying as my answer is moot now. One more thing however:

Don't do it. You must leave the chain long enough to handle bib-big even if you know enough not to do it intentionally. All it takes is one moment's inattention or forgetfullness and the damage can be profound.