Question about freewheel and shifting

maxrodgers

Hello everyone,

I have a classic Dawes Galaxy 10 speed road bike. I have 5 cogs at the back and 2 chain rings at the front. My shifting is done via downtube friction shifters. My trouble is that there is a particular cog I shift from whereby the chain skips a whole cog. This is only a problem on the rear cogs and only really when moving down the gears. I can get the chain onto the skipped cog but I have to move the friction shifter very slowly and gently, much more so than for the other gears. This takes a lot of my attention and doesnt seem very safe as a result. Does anyone know what could be causing this?

I am working with the assumption that it is the rear freewheel rather than the derailleur simply because I would prefer it that way but I suppose it could just as easily be a problem with the derailleur, although that wouldn't explain why it shifts fine on other cogs. Do you think that it is likely to be the freewheel?

The second part of my question is if I do need to change my freewheel then should I change my 5 cogs for another 5 cog one or can these old road bikes fit a 6 or 7 speed possibly?

Regards

simon_masterson

It could just be that the freewheel and/or chain is a bit worn. I've had this happen before.

As for the freewheels you can use, measure the rear spacing. Older 5 speeds (like my favourite) are often spaced 120mm (and so are ideal for running fixed), but newer ones, particularly those made after 6 speed came in, are often 126mm, which will take a 6 or 7 speed; though in the latter case you may need a new rear mech. The other option is an 'ultra 6' freewheel - these were 6 speed freewheels with narrower spacing to fit the old frames. I've never tried one myself, but Hilary Stone usually has them. And of course, you can cold set the stays to increase the spacing, but I wouldn't attempt this unless you know what you're doing.

MichaelW

"My trouble is that there is a particular cog I shift from whereby the chain skips a whole cog."
Is this at a cross-chain angle?

"though in the latter case you may need a new rear mech"
Why?

I did a 5spd to 7spd upgrade with no issues at all. If you have chain clearance at the chainstay/dropout, it works.

simon_masterson

MichaelW wrote:

"My trouble is that there is a particular cog I shift from whereby the chain skips a whole cog."
Is this at a cross-chain angle?

"though in the latter case you may need a new rear mech"
Why?

I did a 5spd to 7spd upgrade with no issues at all. If you have chain clearance at the chainstay/dropout, it works.

I only state that because not all 5 speed rear mechs will work with the extra cogs - I'd assume it to work fine as well.

keef66

Last year I helped my son restore an 80's Peugeot. It had a 5 speed screw-on freewheel and we've replaced it with a 7 speed without changing anything else.

Your shifting problem sounds a bit odd though. Is the gear cable fraying anywhere? Does the shifter operate smoothly if you detach the cable? Same for the rear mech; is it free to move through it's full sideways range across the rear cluster?

JayKosta

maxrodgers wrote:

Hello everyone,
...
My trouble is that there is a particular cog I shift from whereby the chain skips a whole cog. This is only a problem on the rear cogs and only really when moving down the gears. I can get the chain onto the skipped cog but I have to move the friction shifter very slowly and gently, much more so than for the other gears.
...

---

My guess is that the tooth spacing going down to the cog causes the chain to hit the top of the teeth instead of falling into the valleys. Perhaps count the teeth on each cog to avoid the trouble when buying a new freewheel.

If you install a new freewheel, it is good practice to also have a new chain that is appropriate for the new number of cogs.

Jay Kosta
Endwell NY USA

maxrodgers

Thanks everyone,

I'm pretty sure now that the problem is with the ratty old freewheel so I will be changing that. Having a look around it is plain to see that 5 speed freewheels are on their way out. There aren't that many available and I don't see that situation getting any better with time. This has led me to the decision that I am going to try and respace the rear triangle from the 120mm it is currently to either 126mm or 130mm, I haven't decided which yet. Then purchase and install a more modern freewheel. I'm going to get my LBS to redish the rear wheel (and true them as well as they are in a sorry state) as I would definitely mess that up but I'm confident of doing the respacing myself.

Is it likely that this respacing will require me to replace any other components?

cheers

rolf_f

maxrodgers wrote:

Thanks everyone,

I'm pretty sure now that the problem is with the ratty old freewheel so I will be changing that. Having a look around it is plain to see that 5 speed freewheels are on their way out. There aren't that many available and I don't see that situation getting any better with time. This has led me to the decision that I am going to try and respace the rear triangle from the 120mm it is currently to either 126mm or 130mm, I haven't decided which yet. Then purchase and install a more modern freewheel. I'm going to get my LBS to redish the rear wheel (and true them as well as they are in a sorry state) as I would definitely mess that up but I'm confident of doing the respacing myself.

Is it likely that this respacing will require me to replace any other components?

cheers

5 speed freewheels are not exactly common place but given the number of people who use them it is probably not going to be a problem finding them for the next 20 years or so. If you are paranoid, by two or three as spares and hand them down unused to your descendants. Furthermore, they last far longer than modern cassettes so, having sourced one, the likelihood that you'll need to replace it soon is minimal. Both my 1980 Raleigh Record Ace and my 1986 Randonneur are clearly on their original freewheels.

So, respace if you must (but not to 130) but try to find a better reason to do it! I wouldn't bother.......

That said, the Randoneur I have converted from 6 to 7,8 speed. So far just by easing the dropouts out to fit the wider hub. My plan is to get the spacers and cone bolts ground down a little so that the modern wheels can fit without respacing the dropouts. It should be straightforward (reduce spacer on one side, grind bolt down on the other).

You shouldn't need to replace any other components but you may have to be careful around the smallest sprocket as clearances can be an issue there.

simon_masterson

Respacing to 130mm might be a bit ambitious, but 126mm should work.

As regards 5 speeds, my issue (as one that uses them exclusively at present) is the selection and price - they're out there, but it can be hard to tell how much life a used freewheel has left in it, and good ones tend to go at collectors' prices; NOS or barely used particularly so. I tend to keep my eye out - My Regina 13-20 cost me slightly more than £5 on eBay. I bust the 16t cog recently though, so looking for another to cannibalise!

maxrodgers

Hello, thanks for the comments. I agree that 5 speed cogs are out there but often I keep finding that its the low quality component manufacturers who still make them new because higher quality manufacturers have left them behind. The hope then is by respacing I will be able to use higher quality components which also have more availability.
Why do you both say that 130mm should be avoided and/or is ambitious? Surely it's no different in principle to respacing to 126mm, it's just a bit further. Also would 126mm allow a 7 speed freewheel or is that pushing it?

cheers

team47b

Have a quick read of this, you will then know more than most

http://sheldonbrown.com/frame-spacing.html

JayKosta

About respacing the rear dropouts.....

The frame rear stays probably have cross tubes near where the chain stays meet the BB, and where the seat stays meet the seat tube - increasing the spacing will put tension on those cross tubes that wasn't intended by the frame builder. If there aren't cross tubes, then the increased spacing will put tension on the BB-chain stay junction, and the seat tube-seat stay junction.

On my 5-speed spaced frame, I use an old Sun Tour Ultra 6-speed freewheel, and it works fine.

Increasing the rear spacing might 'sound' easy and beneficial, but there can also be unforeseen problems and costs. Are you willing to take the risk ...?

My recommendation is, try to find an Ultra-6 with suitable gear range, or a regular 5-speed.
Even a new 'no name' freewheel should work fine.

Jay Kosta
Endwell NY USA

rolf_f

maxrodgers wrote:

Hello, thanks for the comments. I agree that 5 speed cogs are out there but often I keep finding that its the low quality component manufacturers who still make them new because higher quality manufacturers have left them behind.

Who are these 'low quality' component manufacturers? How do you know that their freewheels aren't fit for purpose? They probably cost very little and will probably last longer than modern freehubs (chunkier teeth last longer). It won't cost much to find out!

Bordersroadie

JayKosta wrote:

About respacing the rear dropouts.....

Increasing the rear spacing might 'sound' easy and beneficial, but there can also be unforeseen problems and costs. Are you willing to take the risk ...?

I did and it paid off (but I take your point). My 1985 531 frame was spaced at 122mm (originally 120 but a few decades of having a 126 hub squeezed in). I cold-set it to 130 (a la Sheldon) with no problem a year or so ago. The chainstay and seatstay bridges remain unaffected. I've kept friction shifters but the 130 OLN means I have been able to get to new wheels with a SRAM 8 speed cassette.

There's no denying the cadence control advantages of having 8 ratios over 5 or 6 (or of course even 11 if he wants, although the accuracy required for manually shifting so many narrow sprockets might prove a challenge!) so if the OP is willing to risk cold-setting, it would provide a worthwhile upgrade.