Crank Advice

Just looking for a bit of advice regards cranks, a little bit confused about some things.

I'm riding a Dolan ally track frame, first proper track frame after a series of conversions. Currently improving the parts i have on it and looking at cranks and replacing the rear hub.

The rear hub is gonna be a gran compe, so have 120mm spacing, the bb is currently some shimano thing, possibly a UN33 and the cranks are shitty mtb cranks with a 45t chain ring.

I'm a little confused by dura ace cranks, i know the 7600 is 144bcd square taper and the 7710 is 144bcd and octalink splined. these are pretty expensive and the cheapest i've found them is the 7600s for ~150 with chain ring {parker}.

my main question is how different are these from the equivalent dura ace double road cranks, 7400 and 7700 ? I was told the main difference is the bcd {road are 130} and the small lip behind the spider to accommodate the second chain ring. How correct is this estimation?

If i was to get a road version, as they're much cheaper than the track one [second hand], how easy is it to get a good 42mm chainline? would it be a case of getting a bb with the same spindle length as i would for the track one or will the road one move more or less further along the bb spindle and so require me to get a bb of a different length?

alternatively i've been looking at the miche primato advanced chainset or the dia compe gran compe track chainset, anyone any experience with these, in particular the dia compe one?

thanks for any help in advance

Road cranks are designed to sit further out from the BB shell, to accomodate the inner chainring/s.

You would need a smaller spindle than the Track Dura Ace cranks use.

Sheldon has a large database of chainlines with different cranks. I would work out which BB spindle length will give the road DA cranks a chainline of 42mm (most likely what your will be).

also, the dura ace road cranks are hollow. they are no good for fixed gear, especially if u plan to ride on the street. they WILL snap or crack at some point. It's also very difficult to get a straight chainline with the octalink bb type crank arms. the bb's dont come in many sizes, there is a fixed version of the dura ace bb but its about £60 i think. basically dont get thre road cranks!

You're much better off with the old type Dura ace square taper track cranks, which will give you a wide choice of BB's, plus depending on your choice you could always change to Sugino or Campag even.

Road cranks are designed to sit further out from the BB shell, to accomodate the inner chainring/s.

You would need a smaller spindle than the Track Dura Ace cranks use.

Sheldon has a large database of chainlines with different cranks. I would work out which BB spindle length will give the road DA cranks a chainline of 42mm (most likely what your will be).

also, the dura ace road cranks are hollow. they are no good for fixed gear, especially if u plan to ride on the street. they WILL snap or crack at some point. It's also very difficult to get a straight chainline with the octalink bb type crank arms. the bb's dont come in many sizes, there is a fixed version of the dura ace bb but its about £60 i think. basically dont get thre road cranks!

You're much better off with the old type Dura ace square taper track cranks, which will give you a wide choice of BB's, plus depending on your choice you could always change to Sugino or Campag even.

great, exactly the kind of info i was looking for. thought the road cranks would need a different spindle but wasn't aware of the issue with the hollow cranks. thanks for all your help.

gotta work out whether to throw 150 on the square taper DA track chainset or opt for the less expensive miche/dia compe ones.

also, the dura ace road cranks are hollow. they are no good for fixed gear, especially if u plan to ride on the street. they WILL snap or crack at some point.

How many cases of hollowtech cranks snapping have you seen?

also, the dura ace road cranks are hollow. they are no good for fixed gear, especially if u plan to ride on the street. they WILL snap or crack at some point.

The track cranks are HollowTech, so are they not hollow too?

In any case, why would they snap or crack on the street, the road cranks are for use on the street. Or do you mean by 'on the street' jumping off walls and the like?

I'd be surprised if both cranks were not of equal strength

right, so the DA roads are an option really then?

according to sheldon brown a typical road double gives 41mm for the inner and 46mm for the outer. if track chainline is generally 42mm i would need a bb with a spindle 8mm shorter than that i would need with track cranks. what is the standard bb spindle length for track, or does it vary dependent on the track cranks used?

right, so the DA roads are an option really then?

according to sheldon brown a typical road double gives 41mm for the inner and 46mm for the outer. if track chainline is generally 42mm i would need a bb with a spindle 8mm shorter than that i would need with track cranks. what is the standard bb spindle length for track, or does it vary dependent on the track cranks used?

Looks like a lot of people use 107mm: http://www.londonfgss.com/thread3372-4.html

So er...a 99mm BB?....... :S

Edit, just had a thought. It'll be a JIS cranks, so installing on a ISO taper BB spindle will mean it'll sit further in. According to Sheldon 4.5mm further in.

right, so the DA roads are an option really then?

according to sheldon brown a typical road double gives 41mm for the inner and 46mm for the outer. if track chainline is generally 42mm i would need a bb with a spindle 8mm shorter than that i would need with track cranks. what is the standard bb spindle length for track, or does it vary dependent on the track cranks used?

This is dependant on the hubs you are using.

This is dependant on the hubs you are using.

gran compe 120mm, that should be 42mm chainline right?

Which sprocket will you be using?

I know, very tedious.

Looks like a lot of people use 107mm: http://www.londonfgss.com/thread3372-4.html

So er...a 99mm BB?....... :S

Edit, just had a thought. It'll be a JIS cranks, so installing on a ISO taper BB spindle will mean it'll sit further in. According to Sheldon 4.5mm further in.

cool, that prob means a 103mm iso bb then, giving me a theoretical 41.5mm chainline?

bloody hell, it's all a bit of a faff isn't it?! maybe the road crank option is more bother than it's worth. if i got the miche advanced cranks i'd have to try and avoid the miche bb as all i'm reading is problems with it.

.

I'm running Shimano 600 road cranks on the Cuntdor. I don't know what this means for you or the Earth in general. Probably nothing.

I've got Veloce triple cranks with the chainring fitted on the inside of the spider (middle ring) on my fixed hack/mtb. They're road cranks, and when I rode the whole of the South Downs Way in 1 day, they like totally snapped and shit because they were designed to be used on the road, and I should've known that chalk dust from the Sussex countryside combined with the road shock transmitted through rigid forks would act as a catalyst for molecular level breakdown of roadie componentry.

And when I then continued to ride 1000s of miles each year around town on the same set of cranks, they continued to crack catastrophically every day, especially because of London roads, which sense when chainsets are being used in a way that conflicts with their marketing profile.

No shit! My road cranks failed so catastrophically they caused the last ice age! How fucking abysmal is that? Buyer beware dude!

I heard that Charlemagne ran road cranks on a fixed wheel bike, which eventually led to the Nazi occupation of Europe.

Historians think that had he filed the braze ons off his the old road frame he was converting, Hitler might never have been defeated.

FACT.

ive got road cranks on my bike at the mo. working out pretty well.
@hippy: never seen a road crank snap. told by reliable sources - cavendish cycles etc. - that the dura ace road cranks (7703 i think?) are likely to snap/crack when put under the continued pressure of riding on the street, skidding and braking with ur feet. yes the track cranks are hollow too, but they must be made differently???

My patience is likely to snap, if put under the continued pressure of reading bollocks

ive got road cranks on my bike at the mo. working out pretty well.
@hippy: never seen a road crank snap. told by reliable sources - cavendish cycles etc. - that the dura ace road cranks (7703 i think?) are likely to snap/crack when put under the continued pressure of riding on the street, skidding and braking with ur feet. yes the track cranks are hollow too, but they must be made differently???

I would remove those shops from your list of reliable sources then!. Unless they have lab tests to prove it, it just sounds like they are making it up as they go along to me.
What is possibly more likely to snap is a cheap set of cranks that are poorly made, rather than the highest quality Shimano produce.

Talking of snapping cranks. I've put a good bend in my Campag's on the road bike while riding this morning. Must be my legs of steel.

Ho hum - new chainset.

Well I've got a set of DA road cranks that I might swap the 600s out for on the Cuntdor and then I can do some testing of my own.
I will start with the Angry Man Riding Hard to Chase Shithead in Car method, followed by the Angry Man Running Late and Tripping over his bike then throwing it into the footpath method then the crank remover fail technique of hitting cranks with large blunt object then the final Bendy Bus Collision Test.

Those Veloces stood up well to my 'repeatedly smash them against rocks and ruts for 100-odd miles test'.

But if someone in a shop told me to remove them immediately and buy the most expensive track chainset they had in stock, it would just be plain obdurate of me to refuse.

We've got to take into account that some of the cracks in London's roads are way worse for your cranks than a guy with thighs the size of your waist, sprinting up a mountain on the Tour...