Aligning the crank tips and suicide shifter anyone?

[Doormandean]

Hey guys

When you do a full build, do you jig up the frame or can anyone suggest another way of assuring the crank is spot on. I've found with the recent first build, a couple of degrees means it's really out if you're using the outside of multiple sprockets on there.

Also, has anyone used a suicide shifter for gear selection? I've thought about it for my builds as I'm using mountain bike donor frames with oodles of gears but haven't dared approach them yet!

Any suggestions welcomed :lol: :lol: :lol:

 

[deven_science]

I don't use a jig, though I'm thinking of making one. I have a two foot square, or you can just take a long straight edge, then I place the straight edge on either side of the BB, first up and down, then front to back, until it seems to run down the frame the same distance on either side.

 

[Uncle Stretch]

Yep my method exactly. I use a framing square, or my level.
Need something a couple feet long and in that length you will see the difference. Also if you have your
frame in a vise and then level the back chain stays you can plumb the BB and get really close on right.
I tack my BB on close, then start tapping it to where its right. Just don't weld it too good at first. :wink:
A string from the BB/crank holder thing to the back sprocket will tell you alot .

 

[Doormandean]

Maybe because I'm a bit tired, but what's a BB? :lol:

 

[Glen]

Maybe because I'm a bit tired, but what's a BB? :lol:

BB stands for Bottom Bracket... it's that bit at the bottom of the frame (usually ) where the pedals are attached. Here is a google image search link...

https://www.google.co.nz/search?q=botto ... iAfh94CgBg

 

[Doormandean]

Of course it is :roll:

I told you I was a bit tired :lol: Thanks Glen

 

[Glen]

Of course it is :roll:

I told you I was a bit tired :lol: Thanks Glen

No worries... we all have those moments from time to time when we are technically awake, but not actually :roll:

Oh, and by "suicide shift", are you referring to the method of changing gears via a lever or stick mounted somewhere other than on the handlebars? If so, I think they are called "jockey shift" on motorbikes and it's called "suicide clutch". Someone will correct if I am wrong I am sure .

I did try doing it on my bike called BOB (big orange bike) but could not get it to work. I still have the bit of metal I was going to use so it might yet end up on one. That bike was coaster brake and I was trying to come up with a way to retain the coaster brake and have a three speed chainring. I gave up.

I tried again on Mantis, which had four functioning gears on the back, and it worked except for not staying in gear... it would always just slip back.

It should be easy enough to figure out though for someone who is not tired :wink: :wink:

 

[wimpy]

Oh, and by "suicide shift", are you referring to the method of changing gears via a lever or stick mounted somewhere other than on the handlebars? If so, I think they are called "jockey shift" on motorbikes and it's called "suicide clutch". Someone will correct if I am wrong I am sure .

Yep,that's correct. I had a suicide clutch on my '43 HD WLC chopper (750 WW2 side-valve machine). It workes just like the clutch that you find in a car with a manual gearbox. The "suicide" part was, if you put your left foot,instead of your right foot on the ground at a trafficlight. The result of that little mistake was that you'ld slam into the car, that was in front of you. :mrgreen: :mrgreen: :mrgreen: