Douzy Chainline Dilemma
 

:cry: OK, This is bugging me...

I am using a pair of Sugino ALP 170mm cranks for my current project (it came with 2 road chainrings and uses 144bcd; requires JIS cranks according to VeloBase.com)

The only problem (and a big one) is finding the right bottom bracket to meet my 'expectations':

1) I want to use the outer ring for my 1/8 chainring; as opposed to the inner one (I plan on filing the inner tabs if they do not clear the chain-stay)

2) I want to get a perfect chain-line: the current chainline measurement taken with a Shimano "Crmo" 113mm spindle (not DA so it's a JIS square taper????) is as follows:While I was taking the measurements, I noticed the spindle didn't fully insert into the crank; leaving a gap of ~3-4mm (Photo 1). On the other hand, the inside of the crank appears to sit 3-4mm away from the end of the spindle. (Photo 2)

So my questions are:

a) Knowing that the measurements I took above are taken after I have applied moderate amounts of torque with only an allen wrench, do you think the crank bolt will push the crank fully into the spindle (thereby removing the gap in Photo 1) if I use a torque wrench & apply as much torque as possible?

b) My second question depends on the answer to my first question, if the answer to question A is "no", will getting a shorter spindle (ie: 110 / 107mm) enable me to move the crank closer to the frame; allowing me to use the outer ring instead of the inner one? (or do I Have to use the inner side since it's a road crank as opposed to a track one?)

c) Is there a possibility of the crank &/or crank bolts becoming loose after use- if I leave the crank in the position in Photo 1 by not tightening the crank bolt enough?


I know these are a lot of questions, but I can't seem to answer them myself with what I know and after researching the interwebs for quite a while now. I hope you guys can give me a hand! :love:

You're thinking way too damn hard. 3-4mm before even tightening the crankbolts?

That's gonna be like 1-2mm off, if even that. Tighten up and ride.

Why would you not tighten the crankbolts and measure reality??? Afraid that would give you an answer and you couldn't dream up another dozen questions?

3mm off. Do you know how little that is??

I'm with the others, do it all up and see what you're left with. Dunno that it'd fuss about a perfect chainline either - my experience suggests it's almost impossible to check the chainline visibly, once you get it pretty close that is, so I suspect that most are riding bikes with chainlines that aren't perfect.

Quote:

---

Originally Posted by gregjones

Why would you not tighten the crankbolts and measure reality??? Afraid that would give you an answer and you couldn't dream up another dozen questions?

---

Well, I foolhardily ordered a 107mm BB thinking that'd allow the crank to move 3-4mm toward the frame without considering the factors I wrote above last night. I am going to the shop today and tighten the bolt and see whether the gaps will still be present when the bolts are tightened.

Will I ruin the crank's taper if i tighten it too much?

Nah, not as long as you do it rather than your tame gorilla.

Seriously, you DO NOT adjust the chainline by tightening the crank. You do the crank up properly and THEN see what's needed to get the chainline straight.

i really like the look of those cranks....look similiar to my shimano 600 but in a 144 bcd. tempting :)

let me know what bb gets you the best chainline on the outer ring.

Are you expecting that the end of the BB spindle should be flush with the crank bolt seating face when the crank bolts are fully tightened? This won't happen. If it did, then the bolts would no longer be pushing the crank onto the spindle and your crankset really will be loose.

I finally received my bb. the chain was 4mm off on the outer ring so I had to use the inner ring with that bb since nobody (except Phil?) makes 99/100mm bb's lol

millimeters are like inches right?

Use a torque wrench.

How about a JIS 103mm?
http://www.niagaracycle.com/categori...bottom-bracket

4mm is a douzy if I've ever seen one!