Gears question...and wanted part!

[Iain C]

Hi

New on here, and what a great site.

I've rescued my old 1980s Claud Butler from my mum's garage and I've decided to give it a bit of a rebuild. At the moment it's got the really old non-index "gold arrow" Shimano 105 mechs and downtube shifters running on a 6 speed freewheel (not casette).

I've got hold of the later (but still old!) index 105 mechs but not the levers yet. As I won't change the freewheel, I want to know if it's possible to run index levers with a greater number of gears (say 7 index clicks) on that 6 speed freewheel, or is the spacing likely to be out? I've seen some 7 speed shifters on eBay but I'd like to check I'm not wasting money before bidding!

Thanks in advance, and just in case you have not seen my wanted ad, if anyone does have any suitable 105 or similar band on or bar end shifters, please let me know!

 

[hamster]

You should get away with it as the spacing on 6 speed is the same as 7 (5.0mm). You you will just have one unused click in the shifters. It usually works best if you have the unused one at the lowest end, as click 1 (from the smallest cog) usually pulls a bit more cable than the others, to take up any slack.

You also could fit a 7s freewheel, they are still available (even also 8s) as NOS, ignoring the cruddy things that are also around and still in production for Asda pseudo-mountain bikes.

 

[Iain C]

Great, thanks for the reply. I've found (and bought) an downtube mounted Shimano SIS shifter on eBay, it's not 105 but it should do the job.

Thanks for the explanation but I'm being a bit dim, do I want to set it up so that the unused click is with the lever fully forward (ie there is an unused click once you get past top gear/small sprocket), or that once the gear lever is full back and it's in bottom gear/big sprocket there is one more unused click to go?

Thanks again!

 

[one-eyed_jim]

You should get away with it as the spacing on 6 speed is the same as 7 (5.0mm).

Careful. There was quite a lot of variation between different makers, but most sixes have wider spacing than most sevens. Suntour Ultra sixes were narrow, and there were one or two others around.

Personally I'd just friction shift it. It's generally not worth the bother indexing the older stuff.

 

[Iwasgoodonce]

If you're very quick you could bid on these!

http://cgi.ebay.co.uk/eBayISAPI.dll?Vie ... 0030990679

 

[hamster]

But Shimano 7 and 8 are effectively interchangeable even though there's a 0.2mm difference in cog pitch - 1.2mm at the far end of the range. So it should work OK. The floating top jockey will do it fine.

As for where the first click should be, that's with the lever forward (cable slackest)

 

[one-eyed_jim]

But Shimano 7 and 8 are effectively interchangeable even though there's a 0.2mm difference in cog pitch - 1.2mm at the far end of the range.

Yeah, but.

The difference between typical six and seven spacing is more like half a millimetre per sprocket, too much for the floating jockey wheel to accommodate after just a couple of shifts. It's also sometimes variable across the block on pre-indexing (and even some later) freewheels, which can be a nightmare. Trust me, I've tried it.

There are indexable 7-speed freewheels around, and that might be a way to go, but freewheel hubs are always getting bent and broken axles. If the bike's worth spending money on, a cassette hub is the way to go.

In general though, the real advantage of indexing is that it lets you put ratcheting shifters on your brake hoods. Friction-shift downtube levers work fine, and are a lot less hassle than trying to piece together a bastard indexing system that, after all the effort - won't actually work any better. Friction shifting isn't anything to be afraid of.

 

[terryhfs]

Yeah, but.

I totally agree. You can get not quite compatible indexed stuff to work together, but trying to do it with pre-index stuff is a recipe for tears and frustration. There was no indexing so there is no standard spacing. Even the design of the under B/B cable guides can scupper any hope you have of getting indexing to work.

If you can find one then why not just put a indexed 6 freewheel on? It solves the problem, the old one is undoubtedly knackered anyway if it's original. It's only a 2 minute job, for you or a bikeshop if you don't have the tool.

 

[hamster]

I hadn't hoisted in that the freewheel was pre index. The longer cog teeth will also make it a horror with shifting on anything later (mind, you, the long teeth would be why it's lasted so long!)

I totally agree that running bastard systems is a recipe for misery, but that was the whole point of the OP.

And I also agree that a freehub is way stronger with the better axle support. I have a Shimano 92 LX that's done 40,000 miles, mainly offroad and touring. Mind, it's on freewheel body No.5!