It is the buyers responsibility to examine all items to determine if an item is safe for use - the buyer accepts all responsibility for use of items purchased

Shipping Department is Closed as we attend Classic Bicycles Auburn

 We will start shipping orders again on roughly June 14

The online store is essentially closed as the minimum shipping fee is set at a crazy high number

We will re-open the store around June 10th 

 

Join the fun and register Now!  Classic Bicycles Auburn June 7-9th 2024.

# of Columns:

Overview  and observations regarding freewheel threading

There are 4 freewheel threads - BSC (aka English), Italian, French, and ISO.

BSC and Italian threads are very close - but not the same.  They are so close, in fact, that hubs as well as freewheels can be threaded so as to interchange with either and that is what's known as ISO threading.  An ISO threaded hub will play very well with and ISO freewheel of course.  But an ISO freewheel will go nicely on either Italian or BSC threads.  And an ISO threaded hub should accept either a BSC or ISO threaded freewheel nicely.  

That said, a true Italian threaded freewheel will fit a bit loosely on a true BSC hub.  In reality, countless folks have put an Italian threaded freewheel on BSC hubs and it's fine.  But it's possible that under a very strong  or heavy rider the Italian threaded freewheel could strip the hub threads.  This is an extremely rare but not completely unheard of occurance, and for most older riders especially it's a non-issue.  But, should one have an Italian threaded freewheel that's a bit out of tolerance and especially "large", the fit may be too loose.  As an Italian threaded freewheel threads on a BSC hub rather easily, doing so and then going back to a true Italian threaded freewheel on the same hub we think is ok.  

A BSC threaded freewheel can be threaded with some force onto an Italian threaded hub.  But doing so is a bit tough on the threads so once you use a BSC threaded freewheel on an Italian threaded hub, one should always continue to use a BSC (or ISO) threaded freewheel.  We've noticed many wheel sets where it seems like folks went back and forth without considering the threading issues and the hub still seemed fine.  But it's less than ideal.   And we wouldn't risk putting a BSC threaded alloy body freewheel onto an Italian threaded hub.  Maybe it would work, but we'd worry about seizing.

The similarity between BSC and Italian threading is striking.  We've played with some old freewheels made in France that are clearly not French threaded.  Those old freewheels actually fit beautifully on Italian threaded hubs and fit rather beautifully (i.e not loose) on BSC hubs as well!  We think that the old French makers made two threads, one for French and one for BSC/Italian decades before the idea of ISO even came about!  Also, in the past we sold many freewheels that we figured were ISO but in hindsight we think maybe they were true Italian threaded.  We then went and asked some folks who bought them if in retrospect they thought they were "too loose" on BSC hubs, and the response was they really couldn't notice and it seemed fine.  

French threading is a different story.  French thread hub OD's are smaller than either BSC or Italian (and therefore ISO of course) and use of a freewheel that is NOT French threaded is very likely to strip out and destroy the hub and get the rider stranded.  

A final note - it is sometimes unclear what a freewheel's threading is.  Suntour originally was BSC and then they started making their freewheels ISO.  Regina in the 80's/90's started making freewheels in ISO.  And some later brands of freewheels are ISO as well. 

 

 

 

Information

Categories