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Sugino chainring change

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Old 08-05-18, 12:11 AM
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phtomita
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Sugino chainring change

I have a Sugino crankset with 52/40T.
I would like to replace the small chainring to something smaller, 36 or 34. Is that big jump acceptable or is not a good thing?
If it works, where I can find a good chainring to go with the current 52T?

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Old 08-05-18, 12:28 AM
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Sugino still makes nice plain chainrings if you want to keep it in the family: https://www.amazon.com/Sugino-34t-11.../dp/B001GSOO4I

Shifting might be slow or difficult with such a big gap, though. I'd be tempted to replace both as a set with a pair of ramped and pinned rings that will work well together, such as a 48/34 or 50/34. Here's what I did with a similar crank:

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Old 08-05-18, 07:15 AM
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52/36 is a common chainring configuration today.

A bike with a crank as old as yours is likely to have friction shifters. That's a good thing. I wouldn't anticipate any shifting problems. Friction shifting is your friend/
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Old 08-05-18, 07:26 AM
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I think a 36 will work easily. It may depend on your rear derailleur, as well as the difference in sizes on your rear cassette/freewheel. I read somewhere that a 20 tooth difference in front is absolute max.
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Old 08-05-18, 08:30 AM
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https://sheldonbrown.com/cribsheet-bcd.html
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Old 08-05-18, 09:08 AM
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34 50 16t difference, is popular .. sugino still makes the punch cut chainrings,

but a lot of others, now, offer a 110 BCD chainring in 7075-T6, a harder alloy which is machined..

and adds shifting pins to the inside face of the big ring.. helping the up-shift..

QBP , thru bike shops, offers a stainless steel , good for the 110-34t ..extra long wearing,

and also the outers as suggested above for the 110-50t..
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Old 08-05-18, 10:40 AM
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You need to measure the bolt circle diameter. Most older road cranks had a BCD of 130mm, for which technically the smallest possible ring is 38t.

That's a cool looking crank so I can understand trying to keep it as original as possible while expanding the utility of the bike. That said, if you just want to get lower gearing with relatively little importance to the vintage look, it's probably cheapest/easiest to just buy an inexpensive modern compact crank.

If it turns out that the BCD of that crank won't accommodate a sufficiently small chainring, you want to maintain a vintage-ish look, and price isn't much of an object, I recommend https://velo-orange.com/collections/...rankset-34x48t .

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Old 08-05-18, 11:23 AM
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Originally Posted by Retro Grouch View Post
52/36 is a common chainring configuration today.

.../
52/36 was a common chainring configuration 50 years ago. Every Peugeot UO-8 came out of the box with that setup. I don't know that the OP is running for derailleurs and shifters but adding 2 more teeth to the ring difference shouldn't make shifts much harder. At least not if his current setup has no issue with those old-school rings he shows in his pic with no ramps or pins.

Try the 34. Worst case - the shifting will be a little sluggish. You could then replace the outside ring with a 50, get the common difference back and slightly reduce your top gear ratios. (And after the fact outer chainring swaps is easier. No juggling to get the ring past the spider while the crank is still on the bike.) Another fix, if the current front derailleur is an older one would be to go to a current model designed to handle a compact.

(Aside: This is where I do not like the new website. I don't know where the OP lives or the other bikes in his stable. Often that helps in coming up with helpful answers.)

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Old 08-05-18, 11:33 AM
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Originally Posted by cpach View Post
You need to measure the bolt circle diameter. Most older road cranks had a BCD of 130mm, for which technically the smallest possible ring is 38t.

...
cpach, I am near certain that is a 110 BCD crankset. 110 BCD was something Sugino made thousands of in a number of models. (Thank you, Sugino.)

OP, measure the distance between adjacent bolts. If they are 65mm apart, you have a 110 BCD crankset. Very, very common on less than high end road bikes. Many of the "sport" bikes of the '80s and '90s came with 110 BCD. Google Sugino 110 BCD and you will get pages of hits.

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Old 08-05-18, 11:35 AM
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I use friction shifters. My front is a triple 26-42-50. No problems whatsoever going up or down. No pins or ramps either.
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Old 08-05-18, 12:52 PM
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Originally Posted by Jon T View Post
I use friction shifters. My front is a triple 26-42-50. No problems whatsoever going up or down. No pins or ramps either.
Jon
Friction shifters? Those shifters with multi-platform capabilities? Those shifters that improve dexterity skills and cognitive brain processes? (Right on!) My current bikes are 7-speed and 9-speed with friction on one and SunTour Power (ratchet) on the other. Triples like yours. 53-42-28 and 52-42-26. The rings are ramped and pinned which I really don't like. (Chain hits the pin and tries to shift up with small-small cross-overs which I used instead of double shifting for short flattish spells on tough hills and sometimes falls off the middle ring when the derailleur is trimmed for no rub in the large cog. I"d rather the old Sugino "dumb" rings. My hands have the required education.

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Old 08-05-18, 08:01 PM
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Thank you for all inputs. Very glad to know I can try a smaller inner chainring.
The bike I am cleaning up is the Sekai GT 2700 with hi tensile tubing, Suntour Cyclone RD and FD - it was sitting in the garage since March

I was removing the freewheel and it is a 5 speed one, if not wrong 14-26. Is possible to replace it with something with more speeds - 6 or 7?
Thank you again


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Old 08-05-18, 10:39 PM
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From the looks of it, that spoke protector has earned its spot on the bike.
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Old 08-06-18, 06:34 AM
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Originally Posted by phtomita View Post
I was removing the freewheel and it is a 5 speed one, if not wrong 14-26. Is possible to replace it with something with more speeds - 6 or 7?
An "Ultra-Six" spaced freewheel should be a drop-in replacement for the five speed freewheel. A seven speed freewheel would likely require moving spacers around on the axle to get clearance for the smallest sprocket, and then re-dishing the wheel to keep the rim centered over the locknuts. It may also be necessary to re-space the rear dropouts on the frame.
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Old 08-06-18, 11:38 AM
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Thank you John, this is starting to be a fun project and lot of learning
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Old 08-06-18, 11:41 AM
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5 speed freewheels remain in production to keep existing bikes running..

more "speeds" requires greater width..

the above ultra 6 is putting you in competition with collectors
and auction prices for those long ago discontinued freewheels
will cost more than your bike's value..

So I'd say, very overspending on a simple transportation bike..



.....

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Old 08-07-18, 12:29 AM
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Thanks for all the inputs.
Yep, after looking that the ultra 6 sp freewheel are more expensive than the bike itself .... time for other option/approach.

I found an used 5 sp freewheel 14-32 really cheap. Will only get it towards end of month.
In meantime, trying to find a cheap 36T or 34T to replace the 42T.
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Old 08-07-18, 01:45 AM
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You could also measure it and see if it's actually spaced 120mm or 124mm, I think some 5 speed stuff is 124mm spaced.
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Old 08-07-18, 11:28 AM
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Good to know, my current one is at 120mm. Thank you!
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Old 08-19-18, 07:51 PM
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So, the 14-32 freewheel I was supposed to pick up at the middle of the RSVP ride didn't work for the Friday. Back in town stopped by the Recycled Bicycles, close to UW today and found this.
Suntour 6sp 14-17-20-24-28-34 that was cheap and bought it. Getting home, I compared the high with the current 14-26 and it is like 3mm higher.
Then, at Sheldon Brown's it says the ultra is like 2mm higher than the regular 5sp, so is this one I got the ultra 6 by any chance?

Then, around 3PM, quick browsing CL I found there is a super $2 a piece garage sale with bunch of cassete/freewheel, chainset/rings - well got there almost at 4PM the end time of garage sale from CL.
On a box full of cassetes I found a 5sp 14-32 that was in pretty bad shape, but at half price end of sale, it is a no brainer - it is taking bath on mineral spirits now.
I asked about the chainrings and I was told someone bought the hole bulk ...




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Old 08-20-18, 07:32 AM
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The 6-speed freewheel you picture is a "standard" 6, not an Ultra, and requires a 126 mm hub and frame spacing. You could either force a 126 mm hub into your current frame or "cold set" (read bend) it to accept the wider hub without a struggle. You can use your current hub by adding 6 mm of spacers to the non-drive side and recentering the axle. That will reduce the axle protrusion on each side by 3 mm but the resulting 2.5 mm should be adequate. You, will, of course, have to redish the rim.

It will be a lot simpler to find a decent 5-speed freewheel. Here is one source for a new one for only $11:

https://www.universalcycles.com/shop...SABEgLpT_D_BwE
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Old 08-20-18, 09:49 AM
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Thank you HillRider - I actually got an 5sp 14-32 used for $1 on a garage sale and have it inside mineral spirits. I disassembled it yesterday and the internal parts looked ok on a visual inspection.
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