BB size ???

[kerolah]

Hey guys,

i have a Gordonson road bike frame from the 80s/90s and i am buying a new BB for it. My cranks are shimona 600,
i have a square taper BB i ripped out of a old Repco traveler that doesnt fid due to it not having the hole thing in the BB for my crank to sit in

Anyways if anyone could tell me what size i need so i can order one from wiggle, or even better find the cheapest one that will fit from wiggle for me so i can buy and be a happy man.


Cheers

Kai.

[yehuwdiy]

Hey Kai,

There are three things you need to figure out...

1. Measure you bottom bracket shell (on your bike) for width. Should be around 68mm, but this can vary.

2. Measure how wide the axle is that your replacing (from one end to the other). Should be somewhere between 102mm and 120mm. If you have older cotterless cranks that attach with a nut (not a bolt) then measure between the threaded sections.

3. Try to figure out if you have JIS or ISO tapered cranks. This can be difficult. I've often found that googling either the cranks or the bottom bracket, or both if known, for specs the most useful way of determining this.

Also, unless you are going for a very high quality unit then many local shops will be vvery close to the same price as wiggle for bottom brackets. For example, I recently bought a Shimano UN54 (great unit, highly underrated) for $20 from Cycle Surgery over at Florey. Honestly, could it get any cheaper?

[Uncle Grumpy]

Being Shimano 600, I'm going to assume they're JIS and not cottered. As such a Shimano square taper BB will suit, providing the shell and axle dimensions are right.

Kerolah, what do you mean the "hole for the crank to sit in" ?

Grumps

[kerolah]

First off id like to say in not the most experienced in bicycle recycling + repair usually i get the shop to do it. so Sorry about that.

I just took a photo and i think the non drive arm is not a shimano 600 at all DOH .. i must of given away an odd pair to someone who came and picked some up !!!!!
Its not even the same size LOL and doesnt have a self extracting bolt it has jjs 170k1 stamped on the back? if that means anything.
If anyone has as spare one im happy to take it off your hands =] or even one that will work as a replacement for the time being.

I never new bicycle recycling was so hard! Props to everyone who does accomplishes this feat.

yehuwdiy:
1: Good guessing its 68mm
2: i dont have a previous one to measure from
3: tried some googling didnt come to a conclusion but guessing its JIS

Uncle Grumpy:
I tried to say it doesnt have the slot for the bolt.... Sorry, exactly like the image.


this is a photo of my odd pair! :{

[BLU_FZ!]

You need to remove the centre cap, i use a pair of circlip pliers.

You will then be able to mount the crank and spin on the nut to the spindle

Glenn

[yehuwdiy]

Ah ok, with you now Thanks heaps for the photo's, helps a lot! i wouldn't worry about the cranks not matching, would take a keen eye to spot the difference.

***From the photo's it looks like you are doing a single speed conversion? If so then life may be a little more complicated for you. Not impossible by any standard, just need to be careful Explanation below.

So...the problem is that your cranks are high quality and the ones off of the Repco were low quality (comparatively speaking as there is nothing at all wrong with the Repco ones realy). In the 70'-90's it was common practice to make two different types of cotterless cranks; those that needed an axle with a threaded end and those that needed one with a hollow threaded section. The hollow threaded kind were harder and more expensive to make and were therefor considered higher quality. This is the type that the Shimano cranks need.

The other type had a threaded post to which attached a nut. These were cheaper and easier to make and were therefor considered 'lower' quality. This is the type the the Repco obviously used.

Now, you are in a sticky position, and someone on here who actually has these cranks on a bike may know more BUT, I'd guess that you need a 115mm axle length.

Explanation: The older 600's needed a 113mm axle, but they had 3mm of offset on the drive side. A newer spindle/ axle will be symmetrical so you need to add that 3mm which makes it 116mm. 116mm are hard to find, 115 is easy and 1mm isn't going to matter much UNLESS you are going single speed???

If you are going single speed then you will need to figure out spacers/ washers to make the chainline work. This is a whole other discussion. Not difficult, just involved

***Take everything I say with a grain of salt as I have never had these cranks and am no expert. Others here will be able to give you better advice ***

One final thought, what cranks were on the Repco bike? If you just wanted to get your fixie on the road then perhaps just using these, with the axle you have, would be the easiest option....later on figure out what the Shimano cranks need then fit them.

[kerolah]

Thanks Yehuwdiy and BLU_FZ for the replys.

Yes it is a fixed conversion hahaha cant make anything easy around here.
SO not to worry about the crank arms that are different length for now?

Now, you are in a sticky position, and someone on here who actually has these cranks on a bike may know more BUT, I'd guess that you need a 115mm axle length.

Explanation: The older 600's needed a 113mm axle, but they had 3mm of offset on the drive side. A newer spindle/ axle will be symmetrical so you need to add that 3mm which makes it 116mm. 116mm are hard to find, 115 is easy and 1mm isn't going to matter much UNLESS you are going single speed???

How do you even now this... your like the ultimate tree of knowledge Or good at google... MMMM

So your saying i would need a 116mm BB, and then still my chain line wont be straight it will be 1 mm off ?? which matters alot on fixed/single speed ?

and yer i might have to give the rusty repco a shot, but if i try the bb out from the repco and do as blu_fz said i might be able to get a better understanding of what bb i need ?

These are my crank* just one of them hahah http://velobase.com/ViewComponent.aspx? ... &AbsPos=30

[yehuwdiy]

lol...good at google and I tinker a lot Def not a tree of knowledge, that would just make things boring. I love those...Say What...moments too much

That site lists the axle length as 116mm, so we were on the right track there.

Yes 1mm will make a big difference, however this is to be expected and can easily be offset by washers etc. Check our the REAL tree of knowledge for a full explanation with photo's:

http://sheldonbrown.com/deakins/how-to- ... rsion.html

It looks like a lot to do, but really is not. Off to ride my single speed now, be back in a few hours

**EDIT: Forgot to say...I actually meant what about trying the cranks+bottom bracket from the Repco on your other frame? Just as a stop-gap until you get the shimano's sorted. May be more trouble than it's worth, but jsut a thought

[kerolah]

This looks like the best option..

Im using the old repco BB for now as it is 116mm with one of the crank arms from the repco 165mm(not the 170mm odd matching one) and the shimano 600 chainring and crank arm on the other side im goign to take off the one key release bolt and chuck a nut on the end to hold it in place.... untill i can find a matching crank arm and buy a new 116mm BB which i dont know if i have to now because even if i got a new one key release crank arm i dont need a new bb coz ill just nut it on ?? if that makes any sense Hahah

taken from sheldons


Chainring Spacers
For a single chainring, you can add spacers between the chainring and the crank spider.
If your chainring is mounted on the outside of the spider, you can move it to the rigtht this way. If it's mounteed on the inside of the spider, you can move it to the left as shown.

This uses the same 10 mm I.D. spacers normally used on rear hub axles.

Suitable spacers are available in 1, 2, and 3 mm thickness. You may need to use longer "double" stack bolts, especially for the 3 mm size.

Ok so its time to give it a go BRB.

Btw i dont want to use the crank arm and chain ring from the repco as its ugly as hell and the spider connects to the large chain ring with botls i cant undo and i want the 42 tooth chain ring

[yehuwdiy]

Fair enough on not using the repco cranks

As for just using a nut to attach the Shimano crank...mmmm...I wouldn't. The problem there is that the crank needs to be pushed a certain distance onto the taper. This is to get the correct chainline and also to that the tapered hole is not damaged in use. By just using a nut to hold it on you may or may not get the crank on the right distance. Thus, there is a chance you could wreck a beautiful crank.

No, you really need to figure out what your going to do with your chainline. If you have a back wheel already sorted then measure it and you frame as per the instructions on Sheldon's site. Once you have that number you can figure out what bottom bracket length you really need. Mine worked out at 48mm for example, many work out at 42mm, just depends on what your back wheel is mainly.

As for a bottom bracket...honestly, just buy a Shimano UN54. Cheap (about $20) and great, you won't regret it.

Where are you? I'm sure someone on the forums would be in the same city as you and have a donor set of cranks lying around.

[kerolah]

I gave it a rough measure they both came to 44mm but as i said rough so ill measure that again properly tomorrow when i have the time.

The crank arm still gets bashed on to the taper aswell as a bolt if that helps at all ??

As for the new BB now i cant because i dont have a set of cranks that work with a hollow bb and i have the same bb as pictured below installed atm

MM thanks for the help anyway ill get to work and see what happens.

Gotta go to the shop and buy a new extracting bolt for my dia-compe stem because i think i lost it. clumsy me... fingers crosses i can find one.

BTW IM LOCATED IN PERTH NOR. DONATE TO ME PLEASE =]