Converting a ten speed bike

[unionman]

I ride a 34 year old Mercian framed,10 speed.Suntour gear changers,Stonglight/TA chainset and cranks,49/32.5 speed rear block,Suntour.Sealed bottom bracket,[Shimano I think].
After many pannier laden tours over the past 30 years,I now find the limited range of gears no longer conducive to a comfortable ride.
Worry that the frame,[imperial measures] and old,[but well maintained]components probably prevent a conversion to triple chainset,6/7 speed block.
Any advice/comment would be very much appreciated.
Thanks
Unionman

 

[RecordAceFromNew]

Welcome to the forum! Any Mercian that has served 30 years should be treasured, I think.

Much has changed during that time, but many of us here have updated bikes from the same vintage. So knowledge of how to get there is not an issue, what is perhaps more useful initially is to let you know how far one can go, and what might be involved.

You might want to read this and this to get some idea of what obstacles exist and what updating can involve.

It is most likely that the distance between the rear dropouts of your bike is 120mm, you have a freewheel block rather than a "cassette", and your wheels are 27" while road bikes today generally have 700c wheels.

Practically all current hubs are cassette based, for 8 speeds and above, and the road ones require 130mm rear dropout distance. If your Mercian is steel and not more exotic than Reynolds 531, then it can be cold set with care to accommodate such hubs if you wish. However if one is adopting a modern hub one might want modern 700c rim too (because 700c tyre/rim choice is vastly superior - 27" wheels were being phased out already in the late 80s). But since 700c wheels are a little smaller than 27" ones, new brake calipers with longer (+4mm) reach may be required.


There shouldn't be much difficulty in acquiring modern triple chainset, bottom bracket or front derailleur to suit. Similarly for rear derailleur or chain. What you might want to consider, however, is whether you wish to retain your current (friction downtube or bar-end?) shifters, or use modern brifters (integrated brake lever - gear shifters). If you want brifters, some consistency consideration in terms of number of speeds and make is necessary for problem-free indexing.

At the other extreme, if you are happy with just having gears lower than what you have at present, depending on the existing 5 speed block, you might be able to buy a new 5 speed freewheel with a substantially lower gear (i.e. a larger large cog to e.g. 32T or even 34T) without having to change hub/wheel/brake/frame spacing etc. In which case depending on the Suntour rear mech's wrap capacity, in addition to getting a longer chain you might have to replace it with one having a longer cage.

If you have further questions, please just ask.

 

[Smokin Joe]

The dropouts will be 126mm, 120 was single speed. I've never had trouble getting a 130mm hub in 126mm dropouts, just a bit of gentle thumb pressure does the job.

 

[RecordAceFromNew]

The dropouts will be 126mm, 120 was single speed. I've never had trouble getting a 130mm hub in 126mm dropouts, just a bit of gentle thumb pressure does the job.

Sorry SJ 5 speed (and Ultra 6) are definitely 120mm, not 126mm. It is normal 6 and 7 that are 126mm. Track (single speed) are generally 110mm (early) or 120mm (more recent).

My Record Ace originally came with an Ultra 6 block. Unfortunately afaik they are no longer easily available, otherwise they might also be of interest to the OP.

 

[Smokin Joe]

You are quite correct RecordAce, I do in fact recall slotting a fixed hub into an old steel frame in place of the five speed with no spacers needed.

 

[Zoiders]

As a 34 year old mercian it will have been built with 126mm spacing.

Someone may have plugged a 120mm rear hub (rare by that time) into it but I doubt it, 34 years is old but it's not that old component wise.

Just because it has a 5 speed block on it it does not mean it will be a 120, there is nothing to stop you putting a 5 speed block on a hub that can also run 6 or 7, the other way round you might find the wheel needs a respace and redish but thats it.

I would go for new 130mm wheels and not stress about it, cold setting over such a small amount puts no more stress on the triangle than the normal flex form daily riding.

 

[RecordAceFromNew]

As a 34 year old mercian it will have been built with 126mm spacing.

Someone may have plugged a 120mm rear hub (rare by that time) into it but I doubt it, 34 years is old but it's not that old component wise.

Just because it has a 5 speed block on it it does not mean it will be a 120, there is nothing to stop you putting a 5 speed block on a hub that can also run 6 or 7, the other way round you might find the wheel needs a respace and redish but thats it.

I would go for new 130mm wheels and not stress about it, cold setting over such a small amount puts no more stress on the triangle than the normal flex form daily riding.

Zoiders I beg to differ - IIRC practically ALL such quality bikes 34 years ago in this country were 10 speed. Further, this is a link to the pages of a couple of 1978 (i.e. 33 year old) Mercian catalogues including price list - ALL their geared frames and bikes then were spec'ed for 10 speed.

Finally, while a bike having a 5 speed block does not mean it will be a 120, I can't think of many good reasons that would motivate someone to put 5 cogs on a 6/7 speed hubs of a classic, quality, much used bike.

As I said earlier, it is most likely that the OP's bike has 120mm o.l.d. - of course, the proof of the pudding is whatever it actually is.

 

[unionman]

Thanks for responses.
Dropout measurement is 120mm.
Bought new,[Mercian built]700c wheels last year;Mavic A719 rims.Rear wheel built using tha original,[30 year old] Campag hub.
According to Zinn Art of Road Bike Maintenance,dropout should measure 126mm for 5/6/7 speed hub.
Any idea where you can buy a 5 speed freewheel?
Bike is certainly treasured.Kept in a bedroom.

 

[RecordAceFromNew]

Any idea where you can buy a 5 speed freewheel?

You can get up to 28T easily anywhere, even Halford sells one. But if I were you I would get one by Shimano such as this.

5 speed beyond 28T are harder to get. This goes up to 32T.

Please see your Private Message for a 34T one.

As I mentioned earlier depending on what ratio you have at present you will likely need a new, longer chain, and perhaps a long cage rear mech.

 

[Zoiders]

Zoiders I beg to differ - IIRC practically ALL such quality bikes 34 years ago in this country were 10 speed. Further, this is a link to the pages of a couple of 1978 (i.e. 33 year old) Mercian catalogues including price list - ALL their geared frames and bikes then were spec'ed for 10 speed.

Finally, while a bike having a 5 speed block does not mean it will be a 120, I can't think of many good reasons that would motivate someone to put 5 cogs on a 6/7 speed hubs of a classic, quality, much used bike.

As I said earlier, it is most likely that the OP's bike has 120mm o.l.d. - of course, the proof of the pudding is whatever it actually is.

No you are wrong.

A 126 has been a standard for longer than you think and yes people would often run a 126mm with a 5 on it even when 6's were available, audax and touring types would keep spares and not change to 6 or 7 until they ran out of them.

I volunteer with a bike recycling charity and a lot of older kit passes through out hands, you won't find many 120mm wheels, certainly not on a 34 year old bike, 120mm is nowhere near as common as you claim, certainly not in the late 70's.

 

[heretic]

I had a frame made in '84 which was a 120mm. It eventually got built up as an ultra6.
Anyway, cold setting to 135mm for a decent strength wheel is easy with a frame of that age, been there and done it. Personally I'd go for a modern rear hub such as Shimano LX with a 9 speed cassette and mech. That can be used with downtube friction levers and gives a possible range of 11-34T . The 135mm mtb hub makes for less wheeldish so the spokes should last longer. LX is the best of the conventional size axle hubs, above that you get the oversize aluminium ones with smaller bearings, which to my mind are a bad idea for a touring bike.

 

[RecordAceFromNew]

No you are wrong.

A 126 has been a standard for longer than you think and yes people would often run a 126mm with a 5 on it even when 6's were available, audax and touring types would keep spares and not change to 6 or 7 until they ran out of them.

I see, so you figured the OP had a stash of 5 speed freewheels lasting 34 years and "many pannier ladden tours"? Ok.

 

[Zoiders]

I see, so you figured the OP had a stash of 5 speed freewheels lasting 34 years and "many pannier ladden tours"? Ok.

No.

I have a big shelf full of second hand wheels off tourers and road bikes dating back to the 1950's, a great deal of which are 5 speed on 126mm hub, some even take a fixed sprocket on the other side depending on the brand of hub.

When you handle a lot of older bikes and work on them (and I mean a lot) you learn what kit was fitted, you don't make the arbitrary assumption that it "must" be this dimension just because it has "x" component fitted.

Companies and riders used stock up on components, they mixed and matched new and old and companies often only offered the very latest kit as an upgrade to standard lines.

 

[RecordAceFromNew]

Personally I'd go for a modern rear hub such as Shimano LX with a 9 speed cassette and mech. That can be used with downtube friction levers and gives a possible range of 11-34T . The 135mm mtb hub makes for less wheeldish so the spokes should last longer.

I agree with you that mtb hubs should have less dish than road hubs, though manufacturers do pull various tricks (such as the asymmetric rim on my Campag rear wheel) to ameliorate.

But I think as far as dish is concerned modern 8/9/10 speed hubs, whether road or mtb, are likely worse than the vintage 5 speed hubs.

The reason I am saying it is because the sprocket pitches for 5 and (say in your example Shimano) 9 speed are 5.5mm and 4.35mm respectively, so the distances between the extreme cogs are 4x5.5mm (i.e. 22mm) vs 8x4.35mm (i.e. 34.8mm) respectively, a difference of 12.8mm.

Since the 135mm hub is only 15mm longer (i.e. 7.5mm each side) while having to accommodate a block roughly 12.8mm longer on one side, it must have more dish.

 

[heretic]

I'll re-phrase that - the 9 with friction levers gives a good gearing range for not too much money, if you want stronger wheels for touring at the same time then go for the 135mm rear spacing. A Stronglight triple of 48/38/26 plus that 11-34 will cope with Bealach Na Ba plus camping gear. (Yes I've done it!)