Fentuz

Current bikerton is still 14-28 which is freewheel. Again, I don't know, I m only going by manufacturer spec and the 14-28 ratios. From the picture, I cannot say



It looks similar to a Tourney hyperglide cassette but the range are 12-28 or 12-32
https://www.sjscycles.co.uk/cassette...peed-cassette/

https://bike.shimano.com/en-EU/produ...S-HG200-7.html

or this SIS freewheel 14-28 the marking on the biggest cog look very similars to OP's picture
https://bike.shimano.com/en-EU/produ...y/MF-HG37.html

https://si.shimano.com/en/pdfs/ev/MF-HG37%20(ax)-1947/EV-MF-HG37%20(ax)-1947.pdf
https://www.bikeforums.net/21303202-post18.html

Duragrouch

Wiki says:
Fine. Just be prepared for me to rant, if it has a freewheel; "What is this, 1975? Is the Berlin Wall still up? Computing by timeshare on mainframes? Listening to 8-track tapes? Dial telephones?"

kayakkielbasa

I'm not sure whether it will help but that's what he replied 'The bike has a screw on freewheel hub/cassette'

You Tube

This one looks quite similar to mine, 1307 is a lower end model vs 1607 but rear hub looks the same. Maybe You can judge by the film.

Duragrouch

Bike model: Looks like the same bike to me. Yours may have better pedals, metal bearing body versus plastic.

Freewheel: Well that throws a shoe into the machinery! (etymology of "sabotage") That limits your high gear, you can't get an 11 cog on a freewheel I think, and that is critical to getting sufficient high gear with a 42 chainring. I had this all worked out! Too bad you are not experienced at bike mechanics, I would recommend getting a new cassette rear hub at the same holes number (28 I think) and flange diameter, remove the freewheel, unscrew the spokes, and build up the same spokes and rim onto that new hub; Takes skill, but remarkably rewarding to build and true a wheel yourself.

Others on here have highlighted good deals for 20" wheelsets (front and rear), with freehub rears, on aliexpress; shipping is more than amazon, but if grouping a set of front and rear, may be worth it, great prices. They would not need to be 28 spoke, in fact, 32 or 36 is better. I would not go with fewer than 28 spokes. Here is where you need to be careful:
- Must be 20"/406 rims, NOT 451.
- Must be freehub rear (you will see the freehub body and not threads)
- Outer Locknut Distance (O.L.D.) must match your frame. You need to measure this on your frame between the rear dropouts, with the rear wheel off; Could be 126mm, 130mm, 135mm, or other.
- FRONT wheel: If also replacing, need to measure O.L.D. at the fork; Most bikes use 100mm, but Dahons and Terns without disc brakes typically uses 74mm O.L.D.
- Both front and rear hubs should NOT be for disc brakes.

Ride the bike around a while in its current state, see if the proportions fit you well, that's the first thing. If not, the above is all for naught, sell the bike and find another. Even if it does fit you well, look around, if you can find a complete bike that is closer to your needs, it may make sense to buy that and sell this one, assuming you can get back your investment. Folding bikes are increasing in popularity, though not as fast as electric bikes. Everyone asks if my folder is electric, based on the frame shape I think, I say no, I bike for the exercise, and an electric would be too heavy for me to carry up stairs, my current bike is already a struggle (due to additional weight of racks and panniers and carried tools).

kayakkielbasa

Duragrouch, so if we already know it's a freewheel I'm a bit limited to 14-32/34T but that's fine for me. You listed a few options for the derailleur upgrade. I'm only wondering - toruney it's a base,low end model, maybe it's better to install something more reliable if I'm doing this upgrade anyway? just asking.

Trakhak

Tourney is at least adequate for most riders. More expensive components will likely last longer and will certainly weigh less, but that's about the extent of the difference.

I used to manage bike stores, including managing the service departments, and I'd have no worries about buying a Tourney-equipped bike these days. (I was snobby about Tourney in my bike shop days, but I've gotten over that.)

If you buy a Tourney-equipped bike, you can always ride it with the stock parts and then upgrade if and when they wear out.

Duragrouch

For my old fancy road race bike, I'd want a fancier rear derailleur. But the fact is, that Tourney on mine has shifted with precision (an easy bar, replacing a Dahon compact derailleur), been bombproof durable (over 10,000 miles since installation, with a LOT of shifting because it is hilly here), and at $13, cheaper than dirt. I needed a claw-mount rear derailleur (under the axle nut) because my frame has no conventional hanger, and the 6/7 Tourney was the only one at my local bike shop. Has worked astonishingly well. And, the mid (GS) cage length was absolutely perfect for my 50/34 2X conversion. Just needed a longer chain. Highly recommended. But since you have a conventional derailleur hanger, you have thousands of designs to chose from. But this one works. Due to the lower clearance inherent in 20" wheels, I'd go with a mid-length (GS) cage, NOT long (SGS?) cage. Not sure you could get away with a short cage with a 34 low.

Note: I don't ride on dirt, only road, only dry. Occasionally lube the rear derailleur pivots. The linkage is still tight as a drum. For more severe use, other derailleurs might be better, don't know.

Also, there is a trickle-down effect with bike parts; For Shimano, new design debuts as DuraAce, then the next year it's on Ultegra, then 105, then Alivio or some other groupset, etc. I went with 105 everything on my road bike 35 years ago, it was always a good value in terms of tech versus price. A Tourney RD now is better than Tourney 30 years ago. And you can make a RD only so good, in terms of the fundamental design of it (since they went to angled pantograph). The pulleys on more expensive RDs may be more durable, may have ball bearings in them or better bushings. The ones on the Tourney are still great, teeth and spindles fine.

Fentuz

from the original subject of your post, you seemed to be interested in an easy and cheap solution. Looking at the picture and manufacturer spec, I think you may have a Tourney HG37 freewheel which has a lock ring to allow cog swap when worn out (I added the pdf link earlier). I don't believe you would need to swap derailleur, just the freewheel with more range and derailleur adjustment.

Now, if you are interested in upgrade etc. it is a slippery slop. if you want to move to cassette, yes, you can change the hub and rebuild the wheel but this is very expensive for what it is and it will be more cost effective to purchase a freehub wheel from hollandbike for example. Then, if you want to swap derailleur etc. , as I mentionned before, there is no advantage to stay in 7 or upgrade to 8 as the modification and maintenance cost is the same as 9speed.
The reason I am saying that is because I went through that with my helios. it was a D7 (budget 7 speed) which I modified copying Dahon speed TT and Tern Verge X18.
https://www.bikeforums.net/folding-b...e-type-tt.html
now, my helios is running a 1x10 Zee groupset rather than 2x9 sora because my wife does not get on with 2x and I had a spare ZEE in a cupboard.

The original helios D7 wheelset was re-used on a minivelo build; I built a Dahon Hammer head D7 from spare part for my mother who learnt to ride a bike at 69 yr young.
https://www.bikeforums.net/22434352-post2.html
It run 14-32 7s freehub with a 45T chainring on 20". the bike is ~8.5kg from memory and she climbs 10% hills without problems

kayakkielbasa

No no, I'd change the cassette only If I had a cassette. If I have a freewheel, I want to stick with it and keep it simple and change the low gear to 34T only, to have a better uphill riding experience.
Changing the derailleur is only due to the fact mine is not capable of moving to 34T (at least that's what they say in the specs).

Duragrouch

I haven't checked specs, but yeah, your derailleur looks old in design, in that it doesn't appear to be an "angled-pantograph" design that shifts the cage lower as the derailleur moves inward to the larger cogs.

Fentuz

I run :
- Sora rd3400 rated up to 27T
- Sora SS r3000 rated for 32T Max
- Altus M310 rated for 34T Max

they all run well with 34/36 sprockets. the r3000 and m310 run 40T without problem too.

your tourney (most likely a RD-FT35-SS) is rate for 28 max so I would expect it to work with 34 or 36 however, you would nee to adjust the b screw.
The big unknown is the 24 to 34 jump hence my suggestion of the IRD Cyclone 7 Speed Freewheel - Shimano Compatible 13-32T: 13 / 15 / 17 / 21 / 24 / 28 / 32
the 28 to 32 jump is normal and the rest of the gap is much better.

or SunRace MFM300-7DV 14-16-18-21-24-28-34 https://www.bike-discount.de/en/sunr...cassette-14-34

kayakkielbasa

Fentuz, thanks.
It seems like Altus m310 is a long cage derailleur. And that leads me to a question if only those low end models like Tourney come with a short cage ?

Trakhak

You probably meant to ask whether low-end models like Tourney come only in a short-cage version. Short-cage versions are, if anything, more common among the high-end derailleurs meant for road racing bikes.

Let me Google that for you.

Shimano Tourney, long cage:

Shimano Tourney TY300 6/7-Speed Rear Derailleur Direct-Attach

Ron Damon

Can you comment on the size of the SS RD versus the Zee RD? Is the Zee shorter still than any other SS model? Certainly looks like that from the product images.

splithub

Jockey wheels axle to axle - 74mm R3000SS, 50mm RD-M640, so the Sora short is not really short compared to 105/Ultegra/DuraAce.

kayakkielbasa

@Trakhak, Nope. I meant if any other slightly higher models like Alivio/Acera i.e. come with a short cage, because I couldn't find any.

Fentuz

I measured them roughly
- Sora rd3400 rated up to 27T --------> derrailleur mechanism is ~60mm and the cage is 60mm
- Sora SS r3000 rated for 32T Max--------> derrailleur mechanism is ~60mm and the cage is 70mm
- Altus M310 rated for 34T Max --------> derrailleur mechanism is ~60mm and the cage is 70mm but also run a much bigger tension pulley

the Zee -------> derrailleur mechanism is ~60mm and the cage is 60mm; the mechanism cam seems to have more range

Fentuz

it is about the same a "new sora SS" RT3000

Fentuz

Yes, the "new Sora SS" is like and old medium sora or medium 105

Duragrouch

Regarding cage length: There is (Shimano terms?):
- Short cage (SS I think)
- Medium cage (GS)
- Long cage (SGS I think)

The Tourney TX I use on my 20" folder is GS, medium cage, has plenty of ground clearance, but still easily accommodates my 50/34 11-30, and should work up to 34 cog which is my eventual plan, which is 39 teeth total capacity required. I think I noted Tourney GS capacity in previous post as 43 (bigger pulley wheels that the Tourney comes with, also help to get that). You might be able to get away with a short cage, if the change in your cog size is within its capacity, and, the largest cog is within its capacity. You don't want a long cage, it will drag on the ground, and you don't need anywhere near that capacity. Long cages are for (wide range) triple cranks with (wide range) touring or mountain cassettes.

kayakkielbasa

So theoretically models like Sora or Claris will also fit?

Duragrouch

Possibly, I'm not familiar with the latest models in those lines. *Always check the numbers*:
- Capacity in teeth (largest cog - smallest cog, for a 1X system)
- Largest cog that it can use
- Compatibility with number of speeds, chain width, and will work with your shifter, if you don't want to replace that.
- (And cage length, as has been previously noted)

splithub

...i used Sora also in 7-speed and 8-speed setups, it worked flawless. I can't see a reason why Claris R2000 and Altus M310 would not. On the chart you see the cable pull for most derailleurs, that one helped me many times already

..and unfortunately there seem to be no quick and dirty way to improve your gearing exchanging only one component

Duragrouch

(above) I'd like to see the footnotes for that. Weird, shifter cable pull going down as speeds increase, that must be pull per gear step. I'd also like to know the shifter style; Brifter, trigger, gripshift, bar-ends, downtube, etc.

splithub

can't find that one, but here is another
https://de.scribd.com/document/39207...-Compatibility
I think it would blow that chart including all shifter types, you can easily look up whats available, for example if you want to use a Shimano 10s MTB derailleur as 11 Speed, you get a cheap SRAM Apex1 thumb trigger.

Oh, i think this one:
https://www.google.de/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.mtb-news.de/forum/attachments/bike-cassettes-drivetrains-compatibility-pdf.1415361/&ved=2ahUKEwjDvcnUyLSEAxXzQvEDHdaeBO4QFnoECBoQAQ&usg=AOvVaw0zuHhW0Z47V357Rk6o2sFv