Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Classic & Vintage (https://www.bikeforums.net/classic-vintage/)
-   -   PX-10 gearing (https://www.bikeforums.net/classic-vintage/1244641-px-10-gearing.html)

nlerner 01-04-22 07:17 PM


Originally Posted by wrk101 (Post 22361843)
Craziest gearing I have ever seen was on a Peugeot I picked up. Stronglight double crankset, 51/49 tooth chain rings. Thats right, a drop of two teeth. It visually looked like the two chainrings were the same size....

The stock crankset on the Raleigh Lenton Grand Prix of the late 1950s/early 60s had 49/46t ring combo. I think it was to discourage shifting the FD!

3alarmer 01-04-22 07:23 PM


Originally Posted by wrk101 (Post 22361843)
Craziest gearing I have ever seen was on a Peugeot I picked up. Stronglight double crankset, 51/49 tooth chain rings. Thats right, a drop of two teeth. It visually looked like the two chainrings were the same size....

...a two tooth difference on chainwheels is something I have used to set up something for flat course Criterium gearing, where you've got very close cogs in the back, with maybe a one tooth difference in the rear. It's an old school attempt to give a lot of variations in a small range, to allow for cadence adjustments. Some of the older cottered crank chainwheel sets were so geared. Gives you a very easy and reliable front shift, assuming you don't require a wider gear range.

I have it on a few bikes.

3alarmer 01-04-22 07:28 PM


Originally Posted by nlerner (Post 22361945)
The stock crankset on the Raleigh Lenton Grand Prix of the late 1950s/early 60s had 49/46t ring combo. I think it was to discourage shifting the FD!

https://cimg9.ibsrv.net/gimg/bikefor...f32e4f0a7c.jpg
https://cimg1.ibsrv.net/gimg/bikefor...2f8e094426.jpg


...you people are so spoiled these days. :(

Road Fan 01-04-22 07:59 PM


Originally Posted by ehcoplex (Post 22361305)
It’s very hilly where I live in the Western Catskills, with many of the secondary and seasonal roads I ride on having quite steep grades. When I got back into cycling last spring I had to rework the gearing on my Cannondale so I could handle the hills (while a touring model, a PO had put a road-triple 30/42/52 and not-very-wide cassette on it- I replaced with 26/38/48 chainrings and an 11-34 7sp cassette). 2k of riding this past season has helped immensely and I find I’m almost never using the granny now, though I’ll want it if I carry panniers, etc, and no doubt I’ll lose a lot of strength over the winter (no trainer, no space for one….). I do pretty regularly end up on 38x34 on longer, steeper climbs, though. So, I’m trying to decide on a gearing arrangement (friction, btw) for my PX-10 build/rebuild now… I’m not really concerned about higher gearing and spinning out on descents- I’m quite happy to coast, because there’s always a steep climb up ahead. It’s the lower end I want to be OK on.

I need ‘new’ wheels for the bike (it came with crappy, steel 27”)- I’m not having luck finding some more-or-less period-correct 700c wheels locally/cheaply, and if I’m going with new wheels I may as well cold-set the frame to 126mm and go with either a 6 or 7 speed freewheel. I’ve got an SLJ long-cage RD (5500, I think). Also have an SLJ FD to replace the original delrin FD which is cracked.

So my choices seem to be-

1) triple-ize the crank and add a 28t granny and run with a 28t large-cog freewheel. I’ve already got a longer spindle for the BB. 6 and 7sp 28t freewheels seem reasonably common… Research indicates the SLJ FD will handle the triple and the SLJ GT RD has the total capacity).

2) Keep the crank as a double and get the smallest chainring I can (37t) and find a freewheel with a 32 or 34t large cog. 34t gives me about the same lowest ratio I’m able to get away with on my Cannondale, and I think I’d do OK with 32t- though it seems like finding a 6 or 7sp freewheel with a 32 or 34t large cog might be a bit harder than 26t large…

3) Cold-set to 130mm, and get a wheel set that takes cassettes… Still leaves me with the double vs triple question and, really, I’m disinclined to cold-set from 120mm to 130mm….. but possibly more availability with cassette gearing?

$-wise, triplizing will cost me a little bit more (triplizer middle chainring + granny ring) than just getting a 37t ring for a double, though maybe that would get offset by being able to use a more common freewheel.

Yeah, sure, there’s the option of gearing the bike as original, but… no. I live on a dead-end road with something like a half-mile of 12% grade…. and then there’s my long, uphill, dirt driveway after that! Original gearing means an unusable bike for me!

Recommendations? Things I’m missing?

I'm again facing the same thing with my Peugeot PX-10 later in the year when I work on it. My idea is to build some 120 mm wheels with maybe a 13/32 rear end, and either a 52/48 half-step, a 50/34 compact/Alpine, or a triple. With these frames sometimes there are French threads which are not compatible with English or Italian. I'll see what will work.

If you have the original crank, you can add a granny most likely, getting a longer Stronglight spindle and get a deeper climbing reserve to negotiate that long 12%. This is not exactly complicated, but finding the right parts may take some effort and learning. But ultimately I think this would be best. I'd look into this possibility first. BITD Stronglight had a very deep catalog, so they nearly certainly had the ability to provide parts to make this modification to your white flyer. Problem today is to identify them and obtain them. But that is what I would go for.

BertoBerg 01-04-22 08:23 PM

I was running a 52/37 on a Stronglight 93 before swapping it out for a Stronglight 99 running a 51/34. The 99 can go down to a 28 if needed.

79pmooney 01-04-22 10:46 PM

I run a triple and 7speed on a Raleigh Competition. A low of 24-28 with stock 28 tooth FWs. Not as nice as my 9-speed good bike with the same low but I won't push a 120OLD past 126. Works very well. (And period correct? Folk have been triplizing PX-10s with TA and Stronglight cranksets forever.)

ehcoplex 01-05-22 07:09 AM


Originally Posted by 3alarmer (Post 22361956)

Impractical for me, but beautiful nevertheless! Let's see the rest of the bike!

sd5782 01-05-22 08:07 AM

Yes, the big half steps are pretty. My 64 Frejus came with a beautiful 47/50 which was too tall for this old man. Sure is cool looking though. I switched it out for a Superbe which looks like a campy and with 42/47 front and 14-32 five speed in back. Still too tall for you.

That Superbe came off of a Trek and was replaced with a 99 copy SR Apex. I settled on a 34/47 front and a 5 speed 14-32 rear even though a 6 fits the rear. I didn’t like the gear progressions with a 6 and the setup now gives a real nice 1.5 step progression although double shifts are the norm. I could run a triple on this crank, but for the generally flatter terrain here I am happy for now. I like the compact double idea, but playing with the gear calc charts seems to end in frustration with even spaces and 6 speeds in back. Good luck on yours.

ehcoplex 01-05-22 08:40 AM

I think I've decided to go with 45/37 double up front and a freewheel with a 32 or 34 large cog. The 52t chainring I have is bent and I'm not sure I'd be able to straighten it out, so going with a triple in the front would mean all new chainrings, and with the SLJ GT I've got I should be OK with the larger cogs in the back. From a purely aesthetic point, a triple with a smaller freewheel would be a bit more 'stealth', and since I have a longer spindle maybe I'll end up there at some point (and my 50+ year old knees may demand it....), but for now doing/buying less is 'more'!


https://cimg5.ibsrv.net/gimg/bikefor...4fbf022188.jpg

jonwvara 01-05-22 09:27 AM


Originally Posted by ehcoplex (Post 22362332)
I think I've decided to go with 45/37 double up front and a freewheel with a 32 or 34 large cog. The 52t chainring I have is bent and I'm not sure I'd be able to straighten it out, so going with a triple in the front would mean all new chainrings, and with the SLJ GT I've got I should be OK with the larger cogs in the back. From a purely aesthetic point, a triple with a smaller freewheel would be a bit more 'stealth', and since I have a longer spindle maybe I'll end up there at some point (and my 50+ year old knees may demand it....), but for now doing/buying less is 'more'!

As Sd5782 noted in #33, if you're using a six-speed freewheel, it's hard to get even spacing between gears with the setup you have in mind. But if you go to a five-speed freewheel, you get very nice, even spacing with a 14, 17, 21, 26, freewheel. The jumps between gears are relatively wide, but I have used that combination often and like it.

I may have mentioned this before, but the best gear calculator I have found is this one:

Bicycle Gear Calculator

Very easy to use and gives a nice visual representation of all the possible combinations.

The 14-17-21-26-32 would combine well with your planned 45-37, and equally well--maybe a little better--with a 46-37. Stronglight rings in 46 teeth are not abundant, but they're out there. That would give you a slightly higher top gear.

Another benefit to that setup: five-speed freewheels in that 14-32 combination were popular in half-step applications, so you might well be able to find an existing example, rather than having to assemble your own. And you'd keep the 120 dropout spacing.

EDIT: This one, for example:

https://www.ebay.com/itm/25517088792...8AAOSwcQxhYZ8P

Not hard to find, evidently--there are several others listed now as well.

ehcoplex 01-05-22 10:35 AM


Originally Posted by jonwvara (Post 22362394)

I may have mentioned this before, but the best gear calculator I have found is this one:

Bicycle Gear Calculator

Very easy to use and gives a nice visual representation of all the possible combinations.

That's pretty cool, and 'seeing' the relationships between the ratios is very illustrative! I also like this one, mainly because it lets you compare two setups side-by-side.

*edit- Aha, I just noticed you can compare 2 setups in the gear-calculator.com one, too!

Medium Size Dog 01-05-22 02:59 PM

https://cimg8.ibsrv.net/gimg/bikefor...d74dcc4793.jpg
Happy Red Clover Triplizer user here! Now happily 52-42-30 front and 14-28 Maillard rear. Flattens out hills nicely. Upgraded the derailleurs and had to dig through hundreds of greasy bottom bracket spindles at the local Bicycle Kitchen Co-op to find a few 3N, 3S and 3T spindles that have the extra length on the drive side but forgot about that pretty soon with the greatly improved ride on this old French bike

ehcoplex 01-07-22 08:09 AM

Quite certain I'll stick with the 93, but boy, the three-arm Touring Sport cranksets look cool. Anybody know what the smallest chainring available for them was?*

*(I assume not easy to find and $$$....)

EDIT- ah, nevermind, found Sheldon Brown's crib sheet. Looks like 35t.

Slightspeed 01-07-22 10:03 PM

For what its worth, on my '78 PR10 I had a couple of gear set ups on it. I didn't like the original 3 arm Stronglight TS, which also had a stripped pedal thread. I had a Sugino GT crank (English pedal threads) laying around, so I tried it with a 52/34 compact set up, which worked out very nicely with the 28t 5 sp rear. The Sugino cranks can also be run as triples. At whenever the last Eroica California was, I found a drilled Stronglight 99 with English pedal threads, and grabbed it. I think it's a 52/36, still with the 28t 5 sp rear (French thread freewheel). I liked the look of the Sugino, but the drilled Stronglight 99 is more French sexy looking, though I miss the 34t granny. If you go to an English thread hub on your new wheelset, you can use a Shimano Megarange 34/14 6 or 7 speed freewheel, which I like very much on my Raleigh with the a Sugino AT triple 52/40/32 (dark green bike). Purists will shriek at the Shimano Megarange, but at 72 years old, still doing big hills, I don't care. You will need a long cage RD for the 34t, but its worth it. First picture is as bought.
https://cimg8.ibsrv.net/gimg/bikefor...4389a1f5ec.jpg


https://cimg7.ibsrv.net/gimg/bikefor...a227b3bf96.jpg
https://cimg8.ibsrv.net/gimg/bikefor...3ca43a9755.jpg
https://cimg5.ibsrv.net/gimg/bikefor...e9a4593836.jpg
https://cimg9.ibsrv.net/gimg/bikefor...01f009fd62.jpg

zandoval 01-07-22 11:49 PM

My vote is bikiniGreen 46/30 up front and a 6 Speed Freewheel 14-34 in back using a long cage derailluer. I have three of my bikes set up this way...

https://cimg1.ibsrv.net/gimg/bikefor...2bdc4d8f02.png

ehcoplex 01-08-22 06:55 AM


Originally Posted by Slightspeed (Post 22365826)
For what its worth, on my '78 PR10 I had a couple of gear set ups on it......
Purists will shriek at the Shimano Megarange, but at 72 years old, still doing big hills, I don't care. You will need a long cage RD for the 34t, but its worth it. First picture is as bought.
https://cimg8.ibsrv.net/gimg/bikefor...4389a1f5ec.jpg

Lovely PR10! I covet in the extreme one of those small Mafac-mounted TA racks! I keep watching the 'bay for one to come up that isn't crazy expensive....
I can't say I won't end up there, but man are those Shimano Mega-range freewheels fUGLY!


All times are GMT -6. The time now is 10:41 PM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.