kayakkielbasa

Hi,

I recently bought a bickerton junction 1607 2018y.
The only issue I have is that I find it a bit difficult to ride uphill.
Since the bike is 7 speed I was thinking about changing rear cassette but I'm not sure whether it's free wheel or free hub. Can anyone confirm?
I'd like to avoid changing the whole wheel if possible. Ideally, I would like to maintain 7 speed cassette, but with different teeth numbers, such as 11-34T (instead of current 14-28T) however, that would require changing the deraileur and the shifter as well.

I know changing front chainring to smaller one would be the simplest option, but I'll reduce the speed of my bike.
Any suggestions?
thanks

Duragrouch

Hello again! Me, from the Eco 3 thread. You are the luckiest person in the world. I am an expert on this subject. First, most likely it is a freehub with cassette on the rear due to 7 speeds, even cheap bikes have gone to this for some time. Only if it was a 6 speed, might I suspect freewheel.

Some on here have advocated going to a much larger cassette with bigger low cogs, as have been used on "1X" ("one-by") bikes, meaning very wide range gearing with only a single chainring, and that is a pretty cool system. Except on a 20" wheel bike. To get low enough gearing for the change you want (same as MY bike, which I will explain), you would need a 46 tooth low cog, and with an 11 tooth high and 52 tooth chainring, gets you 21-88 gear inches. This is enough to spin up good hills or climb standing on *really* steep ones (20% grade), and having enough high gear to pedal down gentle downhills. But 46T rear is extremely marginal in fit, both in rear derailleur to ground, and to tire. It might be finessed with some of the newer rear derailleurs designed for 1X systems. But 1X was designed for bikes with larger wheels than 20"/406. OR.....

You do like my bike, and mount a double-crankset in front. I first tried a 52/42/30 triple, but it wouldn't work, with the FAT seat tube, plus the thickness of the clamped front derailleur adaptor, the front derailleur would not go far enough in for the 30 ring, which overlaps the bottom bracket shell. However, new wide-range double cranks, 50/34, get me almost the same range. With my 11-30 7-speed cassette, I have 21-85 gear inches. I don't need road-race high gears. At the same time, I converted to a newer style crank, called "Hollowtech II style", with "external" bearings which are much smoother, more durable, and capable to adjust the bearings to take out slack. But one thing at a time.

First question: Does your frame have a front derailleur bracket (a "braze-on" welded to the seat tube just above the crank chainrings)?

As a guy I used to know, who grew up in Poland, would say, "F#ckin' A!" (if you click on the pic, it will let you zoom in):



I had to switch the original Dahon "compact" rear derailleur (mounted forward of the axle, worked terrible) to a conventional derailleur, "mid-range" cage length ("GS"). Look how low the derailleur is, acceptable, but that's with a 30T low. A 46T low is gonna be WAY lower, between the rim lower edge and the ground, at best. In fact, I can calculate it: 16T greater diameter, divided by Pi, equals 5 teeth larger in diameter, so 2.5 teeth in radius, 1/2" pitch chain, that's 1.25"/32mm lower derailleur. Not much, but all the difference in the world on 20" wheels. Again, there may be very new rear derailleurs than can finesse a big 1X on 20" wheels and not be that low, I'm pretty sure they make those now, but you will *definitely* need one of those, not just a standard GS rear.

Additional note: You can't go to 8 speed on that 7 speed freehub body, 8 speed bodies are just a bit longer. It's a big question what freehub body is required for newer 1X system, but I suspect it's longer than a 7-speed body. (Which can be changed, for a price, however your frame may also be 130mm OLD (outer locknut distance), and 1X systems might use 135mm.

Fentuz

If you don't want to change the wheel, you will have to stay with freewheel and may consider a old MTB gearing such as
shimano 14-34 : https://www.sjscycles.co.uk/freewhee...eewheel-1434t/
or this 13-34 https://www.sjscycles.co.uk/freewhee...patible-1334t/
and https://www.sjscycles.co.uk/freewhee...eewheel-1334t/

But if derailleur cannot jump from 24 to 34T may be that https://www.sjscycles.co.uk/freewhee...eewheel-1432t/
or this expensive one: https://www.sjscycles.co.uk/freewhee...no-compatible/
13-32 with a 28-32 jump. This last option should most likely require "b screw" adjustment only.

Duragrouch

If you, or a friend, has a bike with the gearing you want, I recommend noting the wheel and tire size, the lowest and highest cogs, and chainring(s), and use one of the "gear calculator" online to examine the "gear inch" range of that desired gearing. Then, do the same calculation with your smaller wheel size, to see if any of the options above will get you your desired gearing. You can completely work this out on paper, before buying anything. I know my setup works, but it's a bigger change.

There are several bicycle gear calculators online:

https://sheldonbrown.com/gear-calc.html

This link is not only a different calculator which displays things graphically, but has the actual gear setup on my bike:
My 20" wheel bike gearing, 50/34 11-30

As you can see from the above, there's a lot of overlap with the double crankset, 5 duplicate gears, which is why I'd love to do a 1X setup if I could, it's just a much tighter fit on a 20" wheel, and might also require a new freehub, and wider dropouts (new bike).

kayakkielbasa

Thanks for the detailed explanation guys.
I can't see any front derailleur bracket, and there is a also curved frame support in the lower part that might block mounting it. I would be happy to post the pictures, but I'm still unable to do so yet.
Same with rear hub - I don't know whether it's free hub or free wheel, that would determine what solutions are possible.
I would also like to stick with more simple solution without additional chainring tbh, but looks like it might be even more complicated.

kayakkielbasa

I forgot to mention that the bike is not with me yet.. it's being shipped from London, so I can't measure anything. I have the pictures only for now.
I tried going uphill with similar Dahon that a friend of mine gave me for a ride. It had the same gear ratios.

Duragrouch

Yeah your big limitation on WAY larger cogs in back (1X cassettes), may be needing to switch the freehub body (and I'm 99% sure it's a freehub, if 7 speeds), but you may be able to go mildly larger and staying with 7 speeds, depends on what the max cog size is for your rear derailleur, my guess would be 34 or 36. That, and a smaller chainring, could get you there. I haven't seen your chainring, if 'rings are bolted on, or the chainring is swaged permanently to the right arm. Before changing my crank from 52 to 50/34, before ordering parts I put on an old 52/42 with no front derailleur, chain only on the 42, and that change alone made a noticeable difference, not low enough for me, but going in the right direction. The 50/34 did it for me, but that was staying with the 11-30 in back. If you perhaps do a 36 cog in back and a 42 in front, that might do it. Running the numbers...

YES!!!! In the gear calc, they don't seem to make an 11-36 cassette in 7-speed (do in 8-speed, that would give you 21.8 gear inches, very close to mine), but 11-34 is common in 7-speed. So, a 42 chainring with 11-34 7-speed cassette, gives you 23.1-71.3 gear inches, that may work for you fine for both climbing and on the flats. You won't be able to pedal downhill, but you don't need to. If your crank has bolt-on chainring, either 130mm BCD (most probably) or 110mm BCD, 42 chainrings are easy and cheap to get. If your crank is swaged, entire cranksets with a 42 ring are ridiculously common both used and on amazon, most road bike setups, you could leave the outer 52 ring on as a chainguard or in case you are doing a bunch of pedaling on all flat ground, you could just switch the chain by hand. My guess is you can get by with your current derailleur (if conventional style and not Dahon compact), possibly same chain length. Anyway, I think that is your cheap solution: 42 chainring, 11-34 7-speed cassette. You might only need to change the largest two cogs and not the whole cassette, if your local bike shop has cheap used parts. But a whole new cassette is USD$ 18.55 on amazon:

https://www.amazon.com/Sunrace-CS-M4...dp/B00JVK7OPO/

I like that one because the gears are generally well spaced. Some cassettes have the 6 highest gears closer, then a big gap to a "bailout low", but that doesn't downshift as well, and your application you'll want more even gear spacing.

Also available in freewheel, if by strange circumstance, you have that instead of a freehub.

EDIT: You don't want a 13-34 or 14-34, yes those were fine on 26" wheel mountain bikes, but with 20" wheels, you're gonna need that 11 high with a 42 chainring. So 11-34.

"Missions are won or lost in the planning stages." - Neil Burnside, D-Ops, The Sandbaggers (UK television)

BobbyG

I put an 11/38 7-speed on my Dahon Boardwalk with the original 52 ring up front. That gives me a gear-inch range from 33 to 96. Low enough for my 62-year-old knees in hilly Colorado Springs, and high enough for commuting to work at the same place as my two middle-weight 700c commuters.

The original Neos derailleur could not handle the improved gear range (especially the 11-tooth cog) and broke after a few months. I replaced it with a used. more capable conventional derailler using an adapter.

Here's the story:
https://www.bikeforums.net/folding-b...t-adapter.html

kayakkielbasa

That was my initial thought! Would be great if that was possible.
But there're some things I don't quite understand - according to what You've stated guys, I have a 7speed freewheel, 14-28T. You said I'd be able to replace it with a 11-34T, but the link You pasted gets me to a thing that is described as 'cassette not a freewheel'. So is my rear hub compatibile with this cassette? Sorry for asking these basic questions but these things are not clear to me.

kayakkielbasa

I found something like this, should that fit?
My only concern is it's a bit too cheap to be reliable..

https://pl.aliexpress.com/item/10050...Cquery_from%3A


and here comes my bike, take a look

https://postimg.cc/gallery/LRWTZ11


.

Fentuz

As I put in my original post:

with a small jump 28-32 (relatively speaking), the derailleur cage should be able to deal with that (I run these up to 34/36 and even 40T). with a bigger jump 24-34, it can be a bit of a lottery and the b screw adjustment will be critical (might need a longer screw m4 or m5)


the aliexpress stuff is what I suggested but it might be a knock off rather than a genuine article. The derailleur is however a long cage so I would not bother as you will get ground clearance issues. The chain might also be a knock off; I had one, it lasted 500 miles... when it comes to chain, stick with shimano/sram/kmc.

Note that you will also need special tools (freewheel spanner, chain whip, chain trimming tools)

kayakkielbasa

Ok, I think I'm slowly getting there. I looked through all these available freewheels.
Just wondering - why they're all made in the same way so that the last cog is so much bigger than the last but one? Why the space between the cogs insn't even? And this apply only to these freewheels that contain 34T.

Duragrouch

Since you said the Bickerton bike is made by Tern or Dahon, I very much doubt it has a freewheel, it most probably has a freehub. When you get to see it, if at the rear cogs, just outboard of the 11 cog, you see a small "ring" with inner splines (hyperglide lockring), it's a freehub. EDIT: In the pics, I think I see a lockring, and hyperglide ramps on the cogs.

Please see my previous post with the amazon link; That is an 11-34 cassette (for freehub) with a smaller jump to the largest cog, much less than other cassettes I saw. Note however, that even if "evenly spaced" cogs, at the larger ones, you need more change in teeth to get the same percent change as with the smaller cogs (logarithmic relationship). That's why my 11-30, going from 11 to 30, the "gaps" between adjacent cogs, in teeth, are: 2,2,3,3,4,5. (If the gaps were linear, 2,2,2,2,2,2, at the largest cogs, the percent change would be much smaller than at the large cogs, you would barely feel a difference when you shifted.) Larger gaps than 40 years ago are possible, due to hyperglide ramps on the cogs, helping lifting the chain when downshifting. (Or as I like to say, hyperspaceglide, a little star wars pun there. )

While you have the cassette off to change, put on a clear plastic spoke protector, larger than the largest cog. These bikes, with short chainstays and a lot of chain angle, can occasionally have the chain fall between the large cog and the spokes, and it tears them up, causing spoke breakage. This is more common on the old Dahon compact derailleur, much less with a conventional derailleur, but do it anyway, it's cheap insurance, and doesn't look bad with the clear plastic protectors (I hated the old metal ones). You'll need a protector with hook spacing that works with 28 spokes, that is my bet for the rear wheel, common with Dahon and Tern. EDIT: Pics indicated a spoke protector! Leave it on, unless you need a larger one for the new cassette.

EDIT: More pics comments: Crank is swaged ring, you'll need a new crank with bolts (most probably 5x130 or 5x110mm BCD) to change to a 42 chainring. Yes, I think one of the frame gussets behind the seat tube, might block a front derailleur hanger, perhaps not, it would be close. I think that rear derailleur will work for a 34. Nice that it has a replaceable derailleur hanger. I see bolt connection on head tube for "Brompton style" front bracket, nice, and that also indicates a model that is at most 15 years old, perhaps less.

kayakkielbasa

Thanks for the tip with the plastic protector, I'll keep that in mind.
I had a plan of replacing the crankset, lite pro can provide some nice looking ones including chain protection which is not in my bike anymore, so that's not the case.
But that's an interesting story with this freehub/freewheel..maybe I'll ask at Tern/Bickerton to be sure what they've used, to be 100% sure.

Duragrouch

That deal on aliexpress is fantastic, but I don't like the cassette, cogs not evenly spaced. Look at the example from amazon I showed on my post, perhaps look for similar one on aliexpress for the same deal. OH, and that is a freewheel on ali, not a cassette. Your rear hub is freehub/cassette, from what I can see I think. The rear derailleurs are option for standard mount or claw mount, I use claw mount because my old frame has NO standard derailleur hanger, but yours does, so you would use a conventional mount. But all options there are freewheels, not for your bike.

Duragrouch

I made many revisions to my earlier post, among others, I see in your pics it has a spoke protector.

I doubt you'll reach anyone at Bickerton or Tern, but you can try. Any bike shop that does service, can look at the bike and tell you in 5 seconds if it is a freehub. If it has a lockring (visible without even taking the wheel off the bike), it's a freehub. My old road bike, pre-hyperglide so no lockring, is still a freehub, the smallest cog is threaded. But by the time that Tern and Dahon were producing models with that frame style, those older freehubs had been long since replaced by hyperglide. There was a further slight revision to fit 11 tooth high cogs, then the body lengthened when they went to 8-speeds, and other subsequent revisions. OH, there is even the possibility that you have an 8-speed-length freehub with a 7 speed cassette and a spacer behind it at the spokes side to allow that; If 8-speed-length was more common and cheap than old 7 at the time of manufacture, they would do that.

kayakkielbasa

Thanks mate for all this explanation. I really appreciate Your help.
Let's say this is an 8 speed freehub, if I want to replace my cassette with an 8speed one, does it mean I'd need to replace the chain, crankset, deraiileur etc (8 vs 7 means less space between the cogs meaning narrower chain, or am I missing something ?) - just out of curiosity ;D

Ron Damon

Chain: yes. Because it likely won't be long enough to span the wider cogset
Crankset: not necessarily but you may wish to change it in response to the expanded range afforded by the newly installed cogset
Derailleur: likely as it may not be able to span the new cogset

Duragrouch

Chain: Might not need replacement for length, if they go to a larger low cog AND a smaller chainring (in fact, they might need to shorten the chain as the chainring will go down by 10T from 52 to 42 (actually -5 teeth in the 180 degree chainwrap), and the low cog goes up by 6T from 28 to 34 (again, +3 teeth increase for 180 degrees chainwrap), so chain could be shortened by 2 links, but probably not needed. Chain width, an 8 speed chain will definitely work on 7 speed cogs, that's what I use; The reverse, unknown, possibly, will definitely fit on each cog fine, it's only a question of interference with adjacent cogs. 8 speed cassette, they made the freehub just a touch longer, I don't recall if they thinned the spacers between the cogs, versus 7 speed. Above 8, they definitely started to thin both spacers and cogs, reducing durability of both cogs and chains.

Derailleur: A big fat maybe. We're not talking about a big increase in total width of the cassette. My old road race bike, I swapped the double crank for a triple, a much bigger change, about 50% increase in range, and that double derailleur with road cage worked just fine on that triple, had enough range, and (at least when on the large cog and small 'ring), never dragged the chain on the bottom of the cage. NOTE: I use a 6 speed GS length rear derailleur (Shimano Tourney TX) on my 7, the 6 was the only claw-mount in stock at the LBS, needed because no rear derailleur hanger on my earlier Dahon Speed. Works great, 7 cassette and shifter.

Shifter: Would definitely need to change if going from 7 to 8 speeds.

Crankset: The original 7 crank will fit an 8 speed chain, no problem. But I think they'll be wanting a 42 chainring; One designed for 7 or 8 speed will work, possibly even 9 speed, as the inner teeth did not change as much as the outer chain width. So if they find an older used crank with 42 (most probably a 52/42), it should work fine. EDIT: Cranks come in different length arms. Most probably the original crank is 170mm arms, the most common size. There are guides online for crank arm length versus height or leg length. Even a little too long is not good for your knees. The trend of late, for people spinning fast on roads (not slow mountain climbs), is shorter crank arms. Also, have the seat higher helps, less knee bending, as long as you don't need to rock your hips to reach the pedals.

Note: Cogs wear, and so do chainrings. If buying used, worn cogs can slip (and since cassettes are really cheap cost, buy new). Chainrings also wear, I think the test is, wrap a NEW (unstretched) chain around 180 degrees (half wrap), and then shouldn't be able to lift the chain much in the middle of the wrap, if so, don't use. (Yes? Does someone know?)

kayakkielbasa

And my thought - I'm a bit worried about my current derailleur reach since the cage is very short.

https://bike.shimano.com/en-EU/produ...FT35-A-SS.html

it looks like its max capacity is 28T so I'd have to change it anyway when going to upgrade the rear cassette.

Ron Damon

A big, fat Yes.

Duragrouch

https://www.amazon.com/Shimano-Tourn...dp/B00O7XMG1C/

USD$17 !

I use a very similar derailleur, with claw mount (you don't need), and designed for 6/7 speed on my 7, this one is 8 speed and should work fine on 7 (the index is in the shifter, not the derailleur). Capacity 43 (you only need 34-11=23), 43 would also accomodate a double crank, you might be able to get by with a shorter cage, but this one would allow to mount a 52/42 crank and switch rings by hand if you are on flat ground for a long ride), doesn't say max cog size, but I'm sure it would do a 34.

This next one is very similar, nearly identical to mine, 6/7 speed, and says max cog size 34. I also like that it has a cable pulley, that helps to reduce cable bend. Less than $13 ! (sale, half-off) That's exactly what I paid for mine years ago. Shifts perfect, durable, cheap. The engineer's mantra; "Lighter than air, stronger than steel, cheaper than dirt."

https://www.amazon.com/SHIMANO-Tourn...dp/B01DQ8KA8O/

Fentuz

So far I have considered freewheel only because manufacturer and retailer identify it as a 14-28 freewheel which is what I had on my helios D7. Note that if you search 14-28 7speed cassette, you get freewheel, no cassette. Cassettes tend to be 11-28 or 12-28
https://www.bickertonportables.co.uk...-1607-country/

Why is there a big jump between gear 1 and 2 in the case of 14-34? These were vintage MTB cassette and the big shift was an bail out or mud gear and cheap to make.

Now, OP needs a high resolution picture on the rear cog, then, people can tell what is on this bike.

If the wheel was a freehub rather than a freewheel, as the shimano derailleur ratio and the same for 7, 8 and 9 speed, if OP want to change the ratio, for ~£90 (if not less), they can upgrade to 9 speed (no point to go 8 as it would cost the same as 9). They would need a sora or acera or sunrace 9s cassette 11-34 or 11-36 (£25) , an altus/alivio thumb shifter (and some grips) (£30) and a 9 speed chain (£10).

But, I think it is a freewheel

Duragrouch

I took a close look at the pics referenced in a link, and thought I could see a hyperspaceglide lockring, but I could be wrong, may just be the shoulder of the small cog. Based on the front screw holes on the head tube, which dates the bike as reasonably recent, I'd be astonished if it was a freewheel. It's later year than my Dahon, which has a 7 freehub and cassette, however mine is 11-30.

kayakkielbasa

To resolve doubts I asked the seller He might know since he told me he had made some improvements/changes to this bike.
When he replies, I'll post back and let You know.