Up-grade gear shifters for old 6 speed availability?

Kozak

Have an old bike about 20 years old, make is Emmelle Classic - it looks like what is now termed a 'hybrid' in that the tyres look like mountain bike but not as wide , has Shimano gears but only a cable to tighten/loosen for the front 3 cogs and rear 6 cogs. Have just got a new mountain bike which has paddle type up/down shifters and would like the same on the old one if available. Looking on-line they seem to be for 7 up to 10 speed - would a 7 speed work of will it push the rear mech too far one way or another and would the spacings be out? Rear sprockets apart from some superficial rust are not too worn so if possible would like to keep as is.

Monty Dog

This probably comes under the term uneconomic upgrade, and I'd simply just try and keep the existing drivetrain working, or invest the cost of new parts towards buying a complete (used) bike that meet your needs. Emmelle aren't a high quality brand and I expect your rear wheel is a freewheel, not a cassette meaning you'll probably need a new rear hub / rear wheel if trying to run 7 speed.

Kozak

Thanks for the reply - i'm more used to working on old motorbikes and to my shame in the time I've had the bike I've not done much maintenance so plan to strip the parts and see what condition all the bearings etc are in. Have taken the back wheel off and inside at the sprocket end I can see those splines that look like it should fit using a special removal socket that I'd already optomistically bought on-line.

Probably a basic beginner's question but what is the difference with freewheel / casette?

I just use the bike for getting some exercise and fun/ family runs along the N Wales coastal path at a leaisurely pace so this 'old banger' of a bike will do for now. Maybe if I have a go on a proper fast road bike I might change my mind.

keef66

With a freewheel the ratchet mechanism is built in to the sprocket cluster, and the whole thing just screws on to a threaded part of the hub. When the sprockets are worn out you have to replace the entire thing. You need the freewheel removal tool to engage the splines inside in order to remove it. Because the action of pedalling tightens the freewheel onto it's mounting threads, they can be very hard to get off. Easiest way is to secure the tool in a bench mounted vice, engage the freewheel, then unscrew the wheel anticlockwise. Easier still if the tyre is still on and inflated; better grip for your hands. The new freewheel just screws on. Put some grease or antiseize on the threads first.

With cassettes, the ratchet mechanism that allows freewheeling is contained in a freehub, which is bolted on to the wheel hub. It has outer splines which match those in the cassette sprockets which just slide over it, and the whole lot are secured by a lockring. The lockring is tightened using a splined tool which looks annoyingly like the freewheel tool, but isn't quite the same. To remove it you need to use a chain whip to keep the sprockets still while you unscrew the lockring with the tool. Worn out sprockets can be replaced without needing a new freehub, and vice versa.

keef66

So I'd get some 7 speed MTB type shifters and a replacement 7 speed screw on freewheel

And hope you have a freewheel removal tool and not a cassette lockring tool.

(If the tool seems too fat to fit in the space it needs to go into, that's the likely reason. Been there, done that)

UndercoverElephant

I have a nasty suspicion that 6 speed to 7 speed is a change of drop-out spacing. At least, it is on road bikes. If the frame is steel, you may get away with bending it a bit, otherwise, to change from 6-speed to 7 would require new shifters, wheel, cassette, frame, rear mech...

Monty may well be correct.

keef66

Parkers of Bolton is where I got my last 2 screw-on freewheels

http://www.parkersofbolton.co.uk/p-230- ... wheel.aspx

The only 21 speed shifters they have are the twisty kind

http://www.parkersofbolton.co.uk/p-1288 ... fters.aspx

But I'm sure you can find some trigger types elsewhere

keef66

Son just acquired a mid 80s Peugeot road bike which was originally 12 speed (says 12 vitesse on the chainstay!) but came complete with a 7 speed screw on freewheel. No idea though if a former owner has persuaded the rear dropouts further apart. The rear Campag wheel looks like the original judging by it's state.

keef66

http://www.chainreactioncycles.com/Mode ... elID=55296

cheapish shimano triggers

Hoopdriver

I too would check the drop-out spacing if I were you. I am fairly certain you will need to widen it to accommodate 7-speed - this is possible with a steel frame, but not with aluminium or other materials. You may want to keep your present drivetrain and just run it into the ground.

desweller

I have a feeling that the sprocket spacing for 6 and 7 speed freewheels is the same, so you may well be able to use a 7 speed shifter and just have one unused position on it.

Ebay is your friend: http://cgi.ebay.co.uk/Shimano-Thumb-Shifter-7-speed-systems-/290531516873?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item43a50721c9

EDIT: According to SB it looks like there is more than one variant of 6-speed, so a 7-speed trigger shifter might be a bit dodgy. There are a couple of 6-speed SRAM twist shifters on eBay, and also these.

Kozak

Thanks for all the feedback and advice/info. Will have a go tonight if I manage to get some garage time.

Thanks DesWeller - if I simply put a 7 speed shifter with the existing 6 speed would it still work, or would I end up with either one side or the other accidently trying to shift the rear mech beyond the outer sprocket and risk the chain coming off? - is there someway to blank off the 7th un needed 'shift' or not?

- those twist type shifters may be the best option for my bike. Went into local bike shop where I work and the lady there had a pair of twist shifts - 3 forther front and 6 for the rear(about £16), and she said the Shimano rep was coming later this week she would check with him but she understood that 7 speed paddle type shifters were the minimum.

keef66

"is there someway to blank off the 7th un needed 'shift' or not?"

You can't stop the shifter using all the clicks, but you can set the limit screws on the rear derailleur so that the extra click doesn't do anything. You certainly don't want to be accidentally shifting beyond the biggest sprocket and putting the chain into the spokes!

Monty Dog

You can sometimes squeeze a 7 speed freewheel onto a 126mm hub - depends on the frame / hub and whether the small sprocket doesn't foul the frame dropout - you might get away with redishing the wheel.

Kozak

Started stripping the bike - rear sprocket is a freewheel - the casette removal tool does not fit so need to get to correct one tomorrow.

http://i532.photobucket.com/albums/ee32 ... e/1012.jpg

More problems trying remove crank - will post another question on here about it.

Here's the bike
http://i532.photobucket.com/albums/ee32 ... le/952.jpg

keef66

"And hope you have a freewheel removal tool and not a cassette lockring tool.
(If the tool seems too fat to fit in the space it needs to go into, that's the likely reason. Been there, done that)"

I had a nasty feeling that would happen! I knew I was dealing with a freewheel, so ordered what was advertised as a freewheel remover. Turns out it was actually a cassette lockring tool; couldn't be arsed to return it, and I've subsequently used it repeatedly on my 10 sp road bike. Then took the wheel in to halfords to make sure I bought a tool that would fit.

They look virtually identical, but the walls of the freewheel tool are just thinner.

Make sure you stick the thing in a vice and unscrew the wheel from the (now secured)freewheel. Next to impossible to remove with a spanner.