Bike polo mechanics & fixing

If you use a pipe cutter does it not pinch the steerer tube?

I haz this one

Just take it in lots of small steps and don't tighten it too much at a time. I could be breaking mechanic rules but it's worked fine for me in the past.

Hmm... I've done a bit of reading on it online during my lunch break, I think I might wait and see if anyone has a hacksaw guide. Granted some of the roadies below are talking about crabon fibre forks, but I'm still not sure I trust the pipe cutter.

http://www.bikeforums.net/bicycle-mechanics/685262-cutting-steer-tube-pipe-cutter.html

I've cut loads with a similar cutter without issues. If you're cutting something soft and thin, and really cranking it up then yes you'll end up having to ream the cut. We're talking 2mm steel here, if you crank it that tight you'll just break the cutting wheel!!!

this ^

what spokes people recommend for 700c polo

ACI double-butted, 21p from Cyclebasket.

they good or just cheap em .

You probably won't notice the difference between those and other 2.0-1.8-2.0 double butted spokes.

It's what my wheels are built with. I've snapped a few (when stopping really hard shots ) but they're so cheap it's worth over ordering to carry a few spares.

cool cheers boys

How much does the axle move per tooth change? Is it 1/8"?

It's actually an interesting maths question.

You have a few different variables

1) The angle of the chain compared to the (virtual) chain stay will increase as the chainring gets bigger, the bigger the angle the less difference in length.

And the opposite as the cog gets bigger (assuming it's never bigger than a 1:1 ratio)

2) it will depend on the length of the chainstays too, as again that affects the angle of the chain.

It's say it's ultimately dependant on 4 factors:
l, length between the centres of the two circles
t1, the tooth count of the chainring (and therefore the diameter)
t2, the tooth count of the cog (and therefore the diameter)
p, the chain pitch (a constant in our case)

At some point when i'm super bored I might work it out.

#mathsnerd

Kev, it's obviously some way away but PUSH in Stoke Newington will let you use their tools on a Saturday (mostly). Otherwise, maybe Max has something useful?

I have a very good hacksaw.

Just put masking tape around the tube and you'll be able to cut it perfectly straight

Max - recommendations for decent hacksaw blades? I broke mine a few weeks ago and haven't got round to replacing it yet.

Starrett hacksaw blades

http://www.starrett.co.uk/shop/handhacksawblades/

My hacksaw is a Facom 603f. Its great, really good weight and the blade is auto tensioned and can be fixed in 9 different positions.

http://www.rapidonline.com/Tools-Equipment/Facom-603F-High-Performance-Hacksaw-Frame-49-4501/?source=googleps&utm_source=googleps&IncVat=1&gclid=CJ3l55Di4L8CFW-WtAod2HoATg

#hacksawgeek

Ace, thanks dude

#mathsnerd

#hacksawgeek

I know who I'd rather be in the pub with!

edit: actually scratch that, I'd probably rather be alone...

It's actually an interesting maths question.

You have a few different variables

1) The angle of the chain compared to the (virtual) chain stay will increase as the chainring gets bigger, the bigger the angle the less difference in length.

And the opposite as the cog gets bigger (assuming it's never bigger than a 1:1 ratio)

2) it will depend on the length of the chainstays too, as again that affects the angle of the chain.

It's say it's ultimately dependant on 4 factors:
l, length between the centres of the two circles
t1, the tooth count of the chainring (and therefore the diameter)
t2, the tooth count of the cog (and therefore the diameter)
p, the chain pitch (a constant in our case)

At some point when i'm super bored I might work it out.

#mathsnerd

Aren't there already calculators in existence that will solve this problem?..

http://eehouse.org/fixin/formfmu.php

or

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

Also Kev, you'll be able to borrow my Park SG-6. But yeah, it doesn't leave my workshop, last time it did I didn't get it back for 8 months! I don't have a hacksaw blade though, i'm in similar woes as Moog.

For what it's worth: With steel, I don't see a huge problem with using a beefy pipe-cutter. It'll just take ages. Also pre-SG-6 ownership, and during those 8 enfuriating months, I also did it with a tape guide ala Max.

Aren't there already calculators in existence that will solve this problem?..

http://eehouse.org/fixin/formfmu.php

or

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

Sure, but that's boring.

Sure, but that's boring.

You have a gf now John, I thought you'd changed :(

Ha!

Use two old stems as steerer tube cutting guide.

It's actually an interesting maths question.

You have a few different variables

1) The angle of the chain compared to the (virtual) chain stay will increase as the chainring gets bigger, the bigger the angle the less difference in length.

And the opposite as the cog gets bigger (assuming it's never bigger than a 1:1 ratio)

2) it will depend on the length of the chainstays too, as again that affects the angle of the chain.

It's say it's ultimately dependant on 4 factors:
l, length between the centres of the two circles
t1, the tooth count of the chainring (and therefore the diameter)
t2, the tooth count of the cog (and therefore the diameter)
p, the chain pitch (a constant in our case)

At some point when i'm super bored I might work it out.

#mathsnerd

It's not that interesting a maths question! It's just solving the long side of a right angle triangle (square root of the sum of the length from the center points of the cog and chainring and the difference between the two radius), doubled and added to half the number of teeth on the cog and chainring times the pitch.

But that's basically what you said, so I guess we just disagree on interesting maths questions! :)

As for the steer cutting, does it actually need to be straight? The stem should be above the top and the top cap be pushing down on the stem, I don't think anything's touching the top edges of my forks?

#shitmechanic