Suntour 6sp/7sp block

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DaveyA

Über Member
At the moment I have a 6 sp 14-24 screw on block fitted. I would like to go to 13-21. My question is do I need to stick with a 6 or would a 7sp still fit without any further modifications?
Many thanks.
 

raleighnut

Legendary Member
It depends if you have room on the hub.
 

lpretro1

Guest
If it a screw-on freewheel then 6 or 7 will fit no problem. However, if your shifters are indexed then you'll need to change them as well. If they are friction then you should be ok.
 

mjr

Comfy armchair to one person & a plank to the next
If it's an ultra6 then no, but I think otherwise usually yes if the wheel is dished for 7 - I think you can tell if there's space between the end of the sprockets and the frame (I think that's what @raleighnut is saying). Both regular 6 and 7 are 126mm OLN IIRC.
 

raleighnut

Legendary Member
We have to assume the wheel is not dished for 7, though.
Sheldon offers dimensions to inform any decision. The 7sp block would be 2.4mm wider. This would not fit on my 6sp wheel: it would screw on but not fit between the dropouts.
I think it's whether the hub is a 5-6 or a 6-7, I've shuffled axle spacers around on hubs to get clearance but it either means getting the wheel 're-dished' or as in my case ('s) rebuilding the hubs to get new rims laced on ( I love Maillard 'wide flange' hubs)
 

Ajax Bay

Guru
Location
East Devon
Why do we [have to assume the wheel is not dished for a 7]?
Well you don't have to, but most trying to give good advice will, because the OP says:
At the moment I have a 6 sp 14-24 screw on block fitted
Why would an old wheel be dished for 7sp yet have a 6sp fitted?
Most old style 5sp blocks can be successfully replaced by a regular 6sp as the distance between the small sprocket and the dropout allows this - as you discovered (reported above).
 
OP
OP
DaveyA

DaveyA

Über Member
Thanks for all the advice, sorry I was not able to respond earlier.
All things considered it would make sense to just stick to 6 sp. Anything for an easy life. All I really want to do is lose the 24 sprocket.
 

mjr

Comfy armchair to one person & a plank to the next
Why would an old wheel be dished for 7sp yet have a 6sp fitted?
Most old style 5sp blocks can be successfully replaced by a regular 6sp as the distance between the small sprocket and the dropout allows this - as you discovered (reported above).
Well, why would an old wheel be ready for 6sp yet have a 5sp fitted? Yet that's what I had, the rear dropouts were 126mm (6sp) not 120mm (5sp or old SA AW) and I understand that's not so unusual. Looking at the thing is probably the best way.
 
OP
OP
DaveyA

DaveyA

Über Member
Just out of interest why would an Ultra 6 not fit? How can I tell the difference between an Ultra and another Suntour 6 sp.
 

Ajax Bay

Guru
Location
East Devon
why would an old wheel be ready for 6sp yet have a 5sp fitted?
The OP's freewheel has a 6sp fitted.
With a 126mm OLN a 'bog standard' 6sp block can be screwed on instead of a 5sp with no complications so quite likely the block has been replaced at some time, given it is of a certain age. As I said upthread there is space (with a 126mm OLN) for the extra 2.4mm block width (5 > 6sp): you don't need an 'ultra' 6sp block (to replace the 5sp) unless the OLN is 120mm.
 
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