Retrobike Forum Index

It is currently Tue Nov 19, 2019 9:27 am

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 8 posts ] 
Author Message
PostPosted: Wed Jun 05, 2019 9:20 am 
Dirt Disciple

Joined: Wed Jan 10, 2018 3:10 pm
Posts: 25
Hi, I've just picked up a 1989 'Abilita' built by Paul Wilkins in Dorset, and have a quick question regarding Campag freewheel/hub/Shimano freewheel compatibility.

The guy I bought it from used to race it and it has a really small block on the back, something like 14-20, and I'm really struggling on steep climbs.

Can I fit a 14-28 Shimano 6 speed freewheel, or change the inner ring to a 32?

Thanks!


Attachments:
A2.jpg
A2.jpg [ 510.95 KiB | Viewed 300 times ]
A1.jpg
A1.jpg [ 483.75 KiB | Viewed 300 times ]
Top
 Profile  
 
PostPosted: Wed Jun 05, 2019 9:47 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 9599
Location: New Forest, UK
No way will you get a smaller chainring on that - any more and the bolts would be outside the teeth! 39T is smallest on Shimano.
The cog spacing is the same (5.5mm) on 6 speed, so provided the freewheel doesn't have a strange threading you should be able simply to fit a larger size. Beware however that you may need a longer chain to get the big-big combo to engage (but you should fit a new chian with a new freewheel anyway). ALSO, the rear mech might not like the larger size, the jockey teeth may rumble along the sprocket. This depends on how long the mech hanger is below the axle. If that's the case use a mech dropper to lower the mech (£2 on ebay).


Top
 Profile  
 
PostPosted: Wed Jun 05, 2019 10:49 am 
Dirt Disciple

Joined: Wed Jan 10, 2018 3:10 pm
Posts: 25
hamster wrote:
No way will you get a smaller chainring on that - any more and the bolts would be outside the teeth! 39T is smallest on Shimano.


Doh! :facepalm: I see that now, thanks!

hamster wrote:
The cog spacing is the same (5.5mm) on 6 speed, so provided the freewheel doesn't have a strange threading you should be able simply to fit a larger size. Beware however that you may need a longer chain to get the big-big combo to engage (but you should fit a new chian with a new freewheel anyway). ALSO, the rear mech might not like the larger size, the jockey teeth may rumble along the sprocket. This depends on how long the mech hanger is below the axle. If that's the case use a mech dropper to lower the mech (£2 on ebay).


Hmm...it's not clear from what I can see on Sheldon Brown's site re Campag vs Shimano freewheels (https://www.sheldonbrown.com/freewheels.html)

I'm assuming the Campag hub is Italian threaded and a Shimano freewheel would be ISO threaded? not a lot of difference:

Type Inch Metric
Italian 1.378" x 24 tpi 35 x 1.058 mm
ISO 1.375" x 24 tpi 34.92 x 1.058 mm

I think I'd definitely need something to lower the mech, as it looks really close on the middle cog at the moment.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2019 11:28 am 
Old School Grand Master

Joined: Mon Feb 11, 2008 9:42 am
Posts: 3473
hamster wrote:
No way will you get a smaller chainring on that - any more and the bolts would be outside the teeth! 39T is smallest on Shimano.
shimano is 38 smallest. (I'm running 38/49 on my training bike) Campag is 135mm BCD so it'll be 39T smallest.

Looks like this is the mech
http://velobase.com/ViewComponent.aspx? ... &AbsPos=32

So *should* be ok up to 30 tooth sprocket, if the data is correct. Just need to make sure your wrap is ok.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2019 12:13 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 9599
Location: New Forest, UK
mattr wrote:
hamster wrote:
No way will you get a smaller chainring on that - any more and the bolts would be outside the teeth! 39T is smallest on Shimano.
shimano is 38 smallest. (I'm running 38/49 on my training bike) Campag is 135mm BCD so it'll be 39T smallest.


Indeed 38T with 130mm and 39T for Campag, my brain freeze and wrote Shimano instead of Campag.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2019 12:26 pm 
Dirt Disciple

Joined: Wed Jan 10, 2018 3:10 pm
Posts: 25
Thanks for the replies, that makes life easier for me :)

So, I shouldn't have any issue using a Shimano freewheel on the Campag hub?


Top
 Profile  
 
PostPosted: Wed Jun 05, 2019 12:48 pm 
Old School Grand Master

Joined: Mon Feb 11, 2008 9:42 am
Posts: 3473
*Shouldn't* have any issues. If tolerances are out and it is an IT threaded freehub it *might* not play nice. (or it might be fine.)

Personally, i'd be popping it off and checking which thread it is (or confirming hub model/year and going from that.)

hamster wrote:
my brain freeze
:) Wednesday is a swine for that.


Top
 Profile  
 
PostPosted: Thu Jun 06, 2019 12:34 am 
r.B.o.T.M. & P.o.T.M. Winner
r.B.o.T.M. & P.o.T.M. Winner
User avatar

Joined: Thu Nov 22, 2007 10:51 am
Posts: 2411
Location: Camel Land
If that chainset is a 144PCD then minimum is 41T that you can fit


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: keithglos and 14 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group