Rahzel

I'm trying to fix up my dad's old 10-speed up--he wants to start cycling again after a 35 year "recovery period". He owns a 1960s Crescent 10speed with (I think) 53/42 cranks or something in that vicinity. He now lives in a hilly area, and has determined the gearing to be too high. I'd like to see if I can replace the crankset with something in the neighborhood of 50/34, if that's possible. He's got a 5-speed on the back wheel, of course. I don't know much about cranksets, and even less about vintage bikes like this one.

Is this possible to do? Here are some pictures of the crankset, if it helps:

Yogurt

I'm going to be of no help here and ask for more pictures of the whole bike. That particular brand & color bicycle are personal favorites of mine! You might end up having to change out the derailleurs, I doubt they can handle a range much beyond what's on the bike.

jacksbike

Not sure what the availability of a double crank 50/34 would be right now, but maybe ebay will help. How about considering installing a 5 speed Shimano or Suntour 14-34 freewheel , a long cage rear derailleur, and 4 more links in the chain ? This might be more feasible than trying to find the crankset. Let's see what others think ! Crescent made some nice bikes. I believe that the entire bike line was offerred in orange color only. Sort of like Bianchi selling only mint green bikes.

Rahzel

Okay yeah, that's a good idea as well. So, would I be able to install, say, the following freewheel cluster: https://harriscyclery.net/itemdetails...ogId=39&id=779

if I got a new long-cage RD and a new chain?

Also, is there a chance I can replace just the inner chainring? My dad doesn't use the 53 very much, if I could just change the inner ring to something like a 34 he would have basically all he needs.

divineAndbright

Probably not.. the front derailleur could never handle the tooth difference between the big and small. You should be able to use the compact crank however and just move the front derailleur down a little, and maybe shorten the chain a few links. I think I have a old crank laying around with the combo you need that probably looks exactly like the one on that bike if you want it... I know the big ring is a 50 tooth at least, dont know what the small ring is off hand though.

bbattle

In order to get to a 34 inner ring you'll need a compact crankset with a 110BCD. The lowest inner ring you can get for your dad's crank is a 39 or 38.

You can find compact cranksets online all over the place. You could get one from FSA with a 50-34 or 48-34 or 46-34. I'd get a new bottom bracket, too.

Charles Wahl

Changing the cranks to something with smaller gears is certainly possible, but it's probably not very simple. It's a question of what the equipment is on the bike, and what you can afford to, or are willing to, replace. You might be lucky and need only to replace the cranks and chainrings themselves; or you might also have to replace the bottom bracket. Even buying the parts on eBay, the more drastic solution might run you $75-100.

You might be blessed with a Local Bike Shop that knows the lore of old cranks and bottom brackets; but what's more likely, should you take the Crescent to a LBS with your stated problem, is that they will (with a greater or lesser degree of condescension that camouflages their lack of knowledge) steer you toward buying a new bike.

Now this may sound like an anti-vintage recommendation, but it's not: I have to say that to solve the immediate problem (getting your father a ride that will have lower gearing), it might be better to simply get a used MTB or City Bike with triple chainwheels on your local CraigsList, spending $100 to 150 tops if you shop around. (look for one without strenuously knobby tires for on-road comfort). You could always keep the Crescent for a "restoration project;" if you feel that you want to mess around with old bikes (something that just about everyone here does), then I would take it apart, clean it up, remove the duct tape, and ride it yourself for awhile. If you still want to change its gearing, take your time, learn the arcana, and do it slowly. Or sell it on eBay, where in cleaned-up condition, you could get enough to pay for its replacement.

pastorbobnlnh 

Or you could go to a tighter crankset, say one with 110 bcd with 36 & 46 tooth chainrings and use the same FD. How old is your dad and how would you describe his physical condition?

John E

You will probably need a new bottom bracket, as well, because you have a Sugino Maxy crankset which takes mounting nuts instead of bolts and a smaller than standard spindle diameter.

I would give a smaller inner chainring a shot. You will need to confirm this, but your inner ring appears to have the 3-bolt BCD which was popular on cottered cranksets. If so, a TA Professional ring will fit, a will various Nervar or Stronglight units.

CardiacKid

I have an FSA Vero compact on one of my bikes. It is the only 50/34 compact crank I know that fits a square taper spindle. It is made for J.I.S square taper spindles, but it should be close enough to fit yours, assuming you have an ISO spindle.
https://www.ebikestop.com/Items/004-cr3762?sck=20915619
Sugino makes a compact crank for square tapers, but it doesn't come in anything smaller than 50/36 and is also JIS.
The FSA would appear to be the cheapest and easiest fix. You should be able to keep everything else. I was able to keep my Suntour GPX FD. I just had to lower it.
The main problem is that it doesn't look very period correct, unlike the Sugino.
Edit: John E posted after I started typing. That might be a problem. Although you can pick up a new bottom bracket for under $20, depending on the threading.

vjp

You might be stuck with a crank that fits your existing BB because the Crescent has a Swiss BB (and a French Headset!).

CardiacKid

Nevermind!

jacksbike

I believe that you are right on target-that it probably has a Swiss BB and worse. Probably best to go with the rear derailleur and wide freewheel route. Although I am now not sure what threads the rear hub has. Hopefully English, but if it is French threaded I have never heard of a wide range French threaded freewheel.

cyclotoine

Are you sure it'll be swiss? I have a crescent with french threaded BB but it's a 1971 I think.

vjp

The thread and pitch are the same on the French and Swiss but the the Swiss has LH thread on the fixed cup and the French is RH. I have a 1970 Pepita Special and mine is Swiss but it would not surprise me if yours is French.

stronglight

Looks exactly correct to me. I'd wager that has a 116 mm BCD and chainrings of 36t were once extremely common - often found on many 3-arm cranks, first on cottered cranksets and later alloy as well - as John E. suggested, this was very common on French bikes.

I don't see a problem at all with the front derailleur AND just a smaller inner ring. There seems to be plenty of room below the chain where it is now resting on the smaller chainring. I have one bike set up with a 32x51 rings and just a basic old double front derailleur... it works just fine - seriously, it's only nudging that chain over a few millimeters to the left or right. In fact, Campy actually specified their standard "double" front derailleur for my Nuovo Record Triple crankset (with 36 to 54 teeth), and that derailleur was definitely designed for racing and not for small chainrings.

The main issue with the cranks on this bike that I can see would really be the rather minimal usefulness of the larger chainring for your Dad. Higher gearing which he'd use less than a 48t outer ring. However, if you really wanted to keep the existing crankset, there is no reason that he would ever really have to use his smallest rear cog (highest gear) anyway.

I really wish I were there to break the bike down and work on it myself. You'd really be amazed how sweet any old and long neglected bike can run with just a pretty basic - but, unfortunately labor intensive overhaul [which is costly at a bike shop] and a replacement of some rather basic items like a chain, cables, cable housings, brake pads, and such will take MANY years off a bikes age.

Having myself returned to active daily cycling in my late 40s after a long absence, I think it would be a wonderful thing for your dad. Although I'll warn you, he'll discover the long implanted old memories of his effortless former cycling days will likely be a real shock to him with his now unfamiliar, aged and stiff body. Quite a rude awakening! So, I'd definitely recommend a modern long cage derailleur mated to a wide range freewheel (at least 14-28 or preferably 14-32 for a hilly area) as a very good way to start him back riding with minimum of frustration... and pain!

I would also consider a taller stem or at very least raising that one as high as possible... yes, and that's without even seeing the bike! ... You'd be amazed how those damned things can miraculously shrink over time while sitting unused, and can make a once agile body with limber back and neck suddenly "seem" dismally old, stiff, and out of shape

Rahzel

Alright, wow, thanks everyone for your responses. I have a few questions/comments:

1. It seems that it would be relztively simple just to get a new inner chainring. Where would I be able to find a 3-bolt inner ring of either 34 or 36 teeth? (My dad has said that not using the outer ring very much is not a big deal.)

2. It seems that it would also be easy to get a new freewheel cluster, with a wider range than my dads (which I'm guessing has less than a 12 cog difference between smallest and largest). Where can I find a 5-speed wide-range cluster? A cursory Google search only turned up 6-speed clusters. <<NOOB QUESTION ALERT>> Can I mount a 6spd cluster where a 5spd cluster goes without bending the chainstays? <</END NOOB Q>>

3. Is this the kind of thing that a bike shop will be able to diagnose and take care of quickly and easily? I ask because my dad currently lives in Switzerland and there is a language barrier issue. We'd like to do it ourselves if possible.

Charles Wahl

A 6-speed cluster can work on a bike intended for a 5-speed -- you have to spread the stays apart 6 mm when you install the wheel. The axle should be just long enough to still lodge in the dropouts (assuming that it's 130 mm long); if you're uncomfortable with that, then just buy a longer axle, 135 mm or so.

Suntour (I like their freewheels) made an ultra-6, which was 6 sprockets in the width of 5. They also made an Ultra-7 that was 7 on the width of 6; that's what I ride. They're not super-easy to find, but they are out there. If you're enterprising, these can be disassembled and customized to put whatever sprockets you can find on ebay. Getting the sprockets off can be daunting without using two chainwhips gingerly, or with the use of a sprocket vise (specialized tool); but a good bike shop can do it. Reassembly is a piece of cake, just like reinstalling the freewheel.