sers

I was looking at nagasawas and I saw that they come with a hatta r9400 (109mm jis square taper) bb installed. i was wondering why mr. nagasawa would choose sugino 75's/grand mighty over dura ace.

chicagoamdream

That's also the appropriate bb for old square-taper DA cranks, as well as Suntour Superbes, so there *are* more options than with a Shimano octalink splined system.

Judging from how many keirin frames show up used with Hatta or Sugino 109mm bbs, it would seem like they're the popular choice for keirin riders.

chicagoamdream

That's also the appropriate bb for old square-taper DA cranks, as well as Suntour Superbes, so there *are* more options than with a Shimano octalink splined system.

Judging from how many keirin frames show up used with Hatta or Sugino 109mm bbs, it would seem like they're the popular choice for keirin riders.

sers

how often do they go through a set of cranks. once a season? if so, sugino seems the likely option

masculinfeminin

because. have you seen the grand mightys? so pretty...

Tomity

Hi!! This is Tomity
90% of Japan nearby professinal Keirin rider uses the crank of old square-taper type.
Therefore, Mr. nagasawa equips it with bb of hatta R9400.

The crank of most square-taper type of NJS suits bb of hatta R9400.
Professional Keirin rider doesn't frequently remove the crank usually.

The reason is that square-taper of the crank extends.
The possibility of it that the chain line shifts is high.

There are a lot of fans because Sugino grand mightys is more flexible than Sugino 75s.
Because Shimano octalink splined system should exchange bb, popularity is low.

However, Shimano octalink splined system is a repetition of the installation of the crank and
doesn't have the change in the chain line.

Were you able to understand?
Tomity

onetwentyeight 

Tomity - Are you saying that the Grand Mighty's are not as stiff as 75s??

PS. I got my tomity cog, it is lovely, thanks!

Tomity

Yes!! Almost rider says its opinion
The reason is related to the sectional area of the crank.

In it, I am very honored. Thank you!!

sers

Tomity - are Grand Mighty's less popular than 75's because the Grand Mighty are more flexy?

What are the most popular cranks?

baxtefer

can I guess?
DA 7600's perhaps?

ink1373

i have dura-ace 7600s and they're amazing.

tomity makes a good point though. the new octalink cranks are much better if you plan to remove and reinstall the cranks a bunch, or just want to have them forever. square tapers deform easily. if you don't take the cranks off much, it doesn't really matter, though.

katio

I'm confused, what constitures a square taper crank?

ink1373

if the bottom bracket spindle is square shaped, and the hole in the crank is square shaped, then its square taper.

everything more than 10 years old (or whatever) is square taper. there are some new systems that use splined spindles, with a bunch of dubious "benefits" and the one real benefit of being more durable in terms of remounting repeatedly.

katio

Is it not good for the cranks to remount them often?

eddiebrannan

the end of the spindle (the bottom bracket's axle) is square in shape, and has a slight taper so that it narrows towards each end. if you look at the picture of the sugino crankset posted you see it has a square hole in the middle. the spindle fits into that and the taper (wich corresponds to a matching taper inside of the crank) seats it at the correct distance from the bb shell. newer bottom brackets and cranks use more complicated splined systems (a round spindle with vanes that run along its length which fit into corresponding grooves in the crank. the idea is that the increased surface area of the splined systems leads to less wear. folks around here (and in keirin circles as tomity stated) tend to prefer the older simpler system.

there are two standards of square taper as well (in essence, one japanese, one italian), but that's for another day…

sers

a crankset that is designed to fit on the end of a square tapered bottom bracket spindle.

eddiebrannan

the taper prevents the crank from seating too deeply on the spindle. removing and remounting leads to wear, so they can seat more deeply than intended, which obviously throws chainline off

katio

Ah. I've learned so much today. Gosh, who needs college when you have internet forums!

freddiesan

I hope it's another day today 'cause I would like to know if there are more square taper standars then Japanese and Italian? I have a no name bb on a Vitus track frame that doesn't work with the Japanese square taper. Can I conclude that it's an Italian square taper then? The crank on the frame was a French Nervar crank you see.

Matthew A Brown

I think you just summed up the Naughts.


I heart Tomity.

prodigal son

If it is a Vitus, it is probably a French bottom bracket.

eddiebrannan

see sheldon for bb specifics

https://www.sheldonbrown.com/gloss_bo-z.html and scroll down
https://www.sheldonbrown.com/bbsize.html

nb the standards he's referring to in the first chart refer to the size and threading of the bb cups, not to the differences between square taper standards (ISO - Campy/Miche etc; JIS - Sugino/Shimano etc)

freddiesan

Thanks! Yes I know it's probably French threading when it's a French track frame(haven't found out yet), I just needed to know what type of spindle it was since the Nervar cranks aren't very good and I want to find out what alternatives there are. Think Campagnolo and Gipiemme would work.

sorry for hijacking this thread.