Bicycle Mechanics - Replacing the freewheel on a Freddie Grubb 1970s tourer
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07-20-10, 04:39 PM
I've recently bought an F.H. Grubb tourer to take on a longish trip over the alps. A preliminary excursion to Wales revealed to me that I could really use a lower gear than the present combination of 14-28T 6-speed Shimano freewheel and 50-42 Nervar Star front rings. A man in a shop who seemed as if he knew a bit about it suggested that it would be difficult to change things up at the front, so I was wondering whether I might be able to switch the rear freewheel for something like a 14-32 block.
The rear derailleur is a Shimano Titlist--can't see any more info on it than that. Picture attached--apologies for the general dirt: I haven't had a chance to clean it yet since I returned.
My question is: is there a suitable freewheel available that I might use? Would such a freewheel (perhaps a megarange, though I'd prefer something with more evenly spaced gearing?) be compatible with the Titlist rear derailleur? If not, would it be tricky to replace that derailleur? The Titlist slots into the rear dropouts, behind the axle.
(Separate question: getting the axles straight in the near-horizontal rear dropouts is a bit tricky, since the non-driveside axle hasn't got a derailleur behind it to push it back against.)
I've searched the forums for answers but although there's a lot that's close, nothing seems quite to answer my question. Sorry if I missed something, though.
07-20-10, 05:31 PM
It will be more expensive, but it will be better to go with a triple up front.
This would work with a 24t small ring, a 36 middle and a 48 high ring. http://www.sjscycles.co.uk/product-Thorn-Thorn-110-74-PCD-Triple-Solo-Alloy-Crankset--Silver-1672.htm
Well, I am not sure the titlelist can handle something bigger though it looks like maybe a 32 on the back, but it certainly won't handle a triple.
Without being rude - honest - I used to work on bikes like this in the 70s and not the newer stuff - you have an old bike that I would not have bought in the 70s for touring, let alone 40 years later. The frame has stamped dropouts and middle of the road components which were hallmarks of decent bikes, good bikes, suitable for reliably knocking around town etc. but not a serious touring machine even then. One step up from department store bikes with steel components, one peices cranks, steel rims and spot welded frames. One step below brazed and lugged cro-moly or manganese-moly frames with top notch componenents.
So if you upgrade to new components you will be throwing a lot of money into it and still have an old not so great bike that now does not have its period "charm". Now-people have gone around the world in old steel bikes; Fred Birchmore did it on a one speed in the 1930s.
If you plan on taking the bike on the trip, you may want to find an old bike mechanic and see if he has some parts that would be more suitable for cheap - maybe an old TA Cyclotourist crankset (THE triple of the day-but you would also need a new bottom bracket I believe) - maybe an old wide cage derailleur. For the freewheel, 6 speed threaded cog? (Not splined I presume) - maybe you can find a 32 or 34 tooth low gear but I would not count on getting any selection of cogs (We used to take them apart and rebuild to suit our preferences but that was a long time ago-nowadays I am stuck with whatever I can find stock (I have a 73 Schwinn Paramount)
I would also tear the bike completely apart, overhaul it, and learn how to replace spokes if you need to. (which means taking a tool for your freewheel as well, since on an old bike I would have the most concern on the freewheel side rear spokes) The best way to center the rear wheel is to put the bike upside down and line up the wheel in the center of the frame - you can't push it all the way back on the non-drive side- you are correct.
For the gearing - it depends on the grades in the alps and your fitness. I was able to cross the Rockies with a loaded touring bike and 42 front, 32 rear, but the Rockies do not have particularly steep grades, just long ones.
I checked and if you can score an old Sun Tour VX GT (my husband has this one) it will handle 34 teeth. I don't think anything went higher than 34 on the back. Maybe now, who knows but now won't work on old hubs.
07-21-10, 12:53 AM
nancy - Suntour actually offered an AG freewheel with a 38 tooth low and made an AG dérailleur to match... but these are like hen's teeth.
The Huret Duopar was the only other dérailleur that could handle this extreme gearing range.
Most older Suntour GT models will handle 34 teeth if the bike is equipped with a long enough hangar and these longer hangars were also available to increase the range of many dérailleur.
The Vx Gt is a beautiful piece of work and it is what I use on my touring bike that runs a 34 low and it handles this with no troubles at all from the middle and granny... but you don't want to cross chain this bike into the big / big combo.
For the OP - Your dérailleur is a Titlist DB600 which is identical to a 600 series model 6100 and a fine dérailleur for shifting as many as 28 teeth but it won't handle a wide range like a Suntour GT or Shimano GS dérailleur... the Suntour is superior to the Shimano of this era.
A modern long cage mtb derailleur will handle 34 teeth and can be run on friction... these are easy to get while some vintage bits take a little more searching for.
You will probably want a lower gear than what a 42/34 would offer so fitting a triple with a smaller granny ring would really expand your gearing range.
07-21-10, 01:02 AM
You should be able to find another mounting piece, to mount on there , then a current Deore long cage can be installed
You can get a quality 6 speed freewheel . IRD [merry sales] is one source.
Titilist was made by Shimano whille Sun Tour's patent for slant pantograph was still in effect,
Now everyone uses a variation of that design, now that the patent lapsed.
07-21-10, 02:52 AM
Thanks everyone for the replies. I'm still a bit unsure as to how I should proceed, though--see below!
Nancy: I bought this with the intention of ditching it at the far end of the tour, because I absolutely hate trying to take bikes on planes. Truth is that I've become rather fond of it, but in any case it was the opposite of my intention to buy a high quality tourer, so I'm not surprised that it's no better than decent for its time. (Although of course a little disappointed, because I was hoping that it wasn't a complete dog!) I've already replaced plenty of drive-side spokes (will need to replace them all, I suspect) and overhauled the brakes, but the transmission remains as I found it originally. Taking things apart and putting them back together is not a big problem.
Fletsbob: what's a mounting piece? For the derailleur? Where would I find one?
Sixty-fiver: what is it to run a derailleur 'on friction'?
Because of the prices and because I've never replaced a BB, I'd sooner avoid adding a triple up front. Is the consensus that I could get a 32T freewheel to work? I'm pretty fit (have done many cycle tours on other bikes before, including over the Rockies) and am aiming not to be heavily loaded. Only one big pass to get over, the Petit St Bernard, which looks okay for gradients.
If I wanted a 34T (or the 32T wouldn't work with the Titlist), how would I go about replacing the derailleur, given the non-standard way in which my current Titlist is hung (i.e. from the same dropout as the wheel)? Could you recommend, simply, which freewheel and which derailleur I should get hold of? (I don't care whether it's vintage or not--just cheap!)
If the only thing to do is get a granny ring up front, is there anything I should know about replacing the Nervar Star chainrings and cranks in particular? Something special about the BB? I attach a photo of that. I ask because the guy in the shop that I mentioned suggested that it would be a trickier job than replacing a BB would be ordinarily.
Thanks again for your help, everyone.
I would not call the bike a dog and based on your intended use it makes sense. Just did not want you to think investing a lot in it would give you a top notch bike. For that matter, if you bought some nice stuff, you could always strip it off of the bike to take back with you. I think every old cyclist has a box of "extra parts" lurking around. Yes the old VX GT was a fine derailleur, cheap and plentiful -
Most newer bikes have the wide range derailleurs and triples so there may be options there as well with swapping parts -
Sixty fiver - wow a 38 tooth oldie - Yes I never saw one of those but like you said "hens teeth".
I am not sure what would be particularly difficult about replacing the BB and Crankset unless it was French threaded but I kind of doubt it since it was an English bike. I would be making friends with the guy at the shop.
07-21-10, 08:15 AM
Alas, the guy at the shop was a customer. The shop was not the sort of shop to be dealing in 1970s bikes. So no prospect of befriendment.
How should I determine what kind of BB/front chainset I need, if that's the way forward? I've had a look at the Sheldon Brown stuff on bottom brackets, but I don't know how to judge what I've got before me, and so whether I'll be able to find a replacement chainset easily or not.
(I'm having trouble finding a VX-GT, let alone a 32T freewheel, at the moment.)
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