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Help - Is what I want to do possible?
#1
Hi, first post in this forum.

I don’t know if I’m posting in the right sub-forum so please let me know.

I have this bike:

[Image: bikefull.jpg]

It is a 2003 Raleigh SC-30; yes I know it is old, is ugly and I have to fix that flat tire.

I will like to get the help and feedback of this forum because I want to remove the front derailleur and chain rings [48-28t], leaving only one chain ring and replace the 7 speed [13-34t] freewheel (or cassette I don’t know which one I have), to a 9 or 10 speed. The catch is if it is possible to combine a chain ring and 9 or 10 sprockets in such a way that I can obtain the same combinations that I frequently use which are:

(48-13) – (48-15) – (48-17) – (38-17) – (38-19) – (38-21) – (28-24) – (28-34)

As you can see out of the “21 speeds” I’m only using 8. The 48-13 is inefficient at some speed, when going downhill so I know that I will like to start with an 11t sprocket.

I had visited 3 different LBS and the experience has not being too encouraging. They all basically want me to buy a new bicycle going from $450 up to $700. But when I ask what new bike model has one chain ring in front without a derailleur and a 9 or 10 speed cassette with the combination that I’m looking for, they told me that they don’t have such a thing followed by questions like “why do you want to do that?” and phrases like “that’s not needed”, “you should not do that”, etc., etc.

I know that I have to change not only chain rings and sprockets but I’m not looking to get the most exotic ultra-space age components; actually I want to replace the parts that are needed to be replaced by components that are not crap and better than the ones currently on the bike but not expensive either, like mid or better mid-low entry level if such a thing exists. Here are some close up pictures:

[Image: bikefreewheel.jpg]

[Image: bikebottom.jpg]

So looking at the pictures What have to be replace? Is this doable in an inexpensive way? What combination of single chain ring and sprockets should I get to obtain the combinations that I use must frequently? Ideas, comments, suggestions are all welcome.

Thanks!
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#2
The first problem your going to have is fitting a 9 speed cassette, becuase they're wider than a 7 and need a different hub. Unless, your current hub is a 9 speed, and a 7 speed cassette has been fitted with a spacer behind it.

Assuming you get all that sorted, you next need to work out the "gear inches" of your current favourite front chainring - rear sprocket combinations. Luckily, there are some on-line calculators to help with this: http://www.machars.net/bikecalc.htm

Once you know what your current favourite 8 or 9 speeds work out as in inches, you can mess about to work out what cassette and chainring combination you need to get a close approximation to them. You probably won't get an exact match right through the range.

Having said all that, I don't think you'll cover 28-34, which is 24.3 inches, all the way to 48-12, which is 118 inches with a single chain ring. You'll have to compromise and lose the top and bottom and get something like a 38t chain ring with an 11-34 cassette, which is 33 to 102 inches. Alternatively you can get a slightly bigger or smaller chainring than 38t and decide whether you want to lose the high gears or the low ones.
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#3
Yep, you're going to need a new rear wheel. You can get an entry level one for about $50.
xerxes, isn't he going to run into problems getting the chain to go all the way from cogs 1 thru 9 while on one front ring? Won't it bind?
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#4
(08-10-2012, 02:10 AM)1FJEF Wrote:  Yep, you're going to need a new rear wheel. You can get an entry level one for about $50.
xerxes, isn't he going to run into problems getting the chain to go all the way from cogs 1 thru 9 while on one front ring? Won't it bind?

Shouldn't do, I have a 3x9, 27 speed bike and the chain will happily run on all the rear sprockets with the chain on the middle chain ring up front. If you have a front mech with rapidfire type shifters that have 3 fixed positions, the chain might rub on the front mech when on the outer two, smallest and largest, rear sprockets. Not a problem if you have a friction shifter that allows you to trim the front mech position slightly, or if you have a single chainring and no front mech at all. You will want to make sure the chain line is good though, so that the single front chainring is in line with the middle of the 9 sprockets on the rear.

Another issue is that in this case, you'll need a whole new chainset, becuase this one is a complete unit, with the chainrings spot welded together and fixed to the crank arm.

It's all kind of do-able, but I don't think it would be very economical and I don't think there would be a huge benifit.

I do have a bike with a single chainring up front with a 7 speed cassette. The original triple chainset was worn out and the front mech was junk, so I replaced it with a single chainring chainset and just removed the mech and shifter. The bike is only used for short, around town journeys, so 1x7 was plenty and it was cheaper than a new mech and tripple chainset, but if you have to start replacing wheels, cassetes and shifters to go from a 7 speed to a 9 speed it's going to be expensive.
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#5
Possible yes.

Note: your bike is newer than any of mine. Smile

Currently you have a freewheel not a cassette.

You need a new rear wheel:
http://www.amazon.com/Avenir-Weinmann-Cassette-Compatible-26-Inch/dp/B003RLDSTE/

Cassette:
http://www.amazon.com/SRAM-PG970-Speed-Cassette-11-34T/dp/B000NNQJAY/

RD
http://www.amazon.com/Shimano-RD-M430-Alivio-Derailleur-Black/dp/B004JKCHHG/

crank
http://www.amazon.com/Retrospec-Bicycles-Fixed-Gear-Single-Speed-Crankset/dp/B006A9ZAGE/

BB
http://www.amazon.com/Shimano-Square-Bottom-Bracket-68x118mm/dp/B005DTIDDY/

Chain
http://www.amazon.com/SRAM-P-Link-Bicycle-Chain-9-Speed/dp/B000RWE868/

And as Xerxes noted, you will still not get the ratios you want.

I had a 1X7 bike with a 44T chainring - I pedal slowly, so I wanted a 48T front ring - cheapest way was to purchase a 28-38-48 triple; later I added the FD, and have since sold the bike.

You must have some awfully steep hills to use the 28/34 combo. My SR's lowest is 39/23 - which is more than adequate for what I encounter on my commute. On the high end I have 52/13 which with a strong tail wind in the afternoon, I could go quite a bit higher - on level ground.

Our tandem is now equipped with 26-44-54 and 12-30 7 speed in back. But tandems need lower gears and higher gears than singles.
Nigel
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#6
Yes I do have few small awful steep hills where I use the 28-34 but I think that the problem is more related to the knees of the heavy and old bike """engine""" and those can not be replaced.

Many thanks for your responses. Nfmisso your list is excellent.

Questions, Is something else needed to keep the chain in the chainring?
Are there no 9 speed freewheels? If 9 speed freewheels are available Do I still have to change the hub?
Cassette is the only option?

If that's the case what the people at the LBS has told me make more sense. If I buy a factory 9 speed bike with a replaceable cranks I only have to change the chainrings plus BB and the cassette if needed. No need to buy a new bike though, I can check for an used one. I will check Nfmisso's list against ebay for used parts to see how it goes. So is always the same old story, it seems that almost everything is mechanically feasible but not necessarily cost effective.

Also I was afraid that you will told me that I won't get all the "gain inches". I was looking not to loose those but "waist" inches :-)
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#7
Already 7 speed freewheels were a really bad idea. The freewheels are rather wide and the hubs bearings sit very close to the centre on the drive side, so there's a long, unsupported distance with lots of force acting on it. The axles were prone to bending. So: no freewheels anymore.

The 9 speed MTB cassettes offer a very wide range (11 - 34 teeth), an 11 teeth sprocket is the smallest you can go. So with a 28 teeth chain ring you will never ever reach the 48 / 13 ratio you are using at the moment (you'll not even come close, 28 / 11 equals about... 48 / 19). For the wide gear range you need you will need either a compact crank set (2 chain rings, cyclocross bikes use 30 and 46 teeth) or a triple crank set. Or you change to one of the internally geared hubs (there's a bunch quite nice ones by SRAM without the back-pedalling hub brake). Might be an option?
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#8
Joe makes some excellent points. If you are putting a lot of shock load into a hub, definitely avoid freewheels, and go with freehubs with cassettes. If you are gentle on the hubs, even 7 speed freewheels are okay on well made hubs with premium heat treated cr-mo axles. A properly designed freehub puts about half the bending load on the axle compared to a cassette hub; and freehubs allow space for larger diameter axles. Stength of a shaft is proportional to the shafts diameter raised to the fourth power; thus a 12mm diameter axle is twice as strong in bending as a 10mm diameter axle.

Bottom line 3d1l; what you want to do is not possible with standard bicycle components - you'd have to give up either the high end (speed) or low end (hill climbing); and it would cost you more to modify your existing bike than to purchase new.
Nigel
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#9
I came back to tell you that I kept reading and founded this (it applies to the "freehub/cassette" setup but it made me felt I wasn't too crazy):

http://www.bikeradar.com/gear/article/workshop-how-to-convert-your-mountain-bike-to-1x9-or-2x9-gearing-29342/#null

It's a year old article so the concept is not new at all.

Then I keep looking for components and found this:

http://www.bicycleoutfittersindy.com/product_p/fw4629.htm

It is out of stock at this moment but they also have a 9 speed freewheel version. I call them and emphatically and specifically asked if these were not cassettes but threaded multispeed freewheels for a threaded hub and they said "yes". I then asked if I can replace the 7 speed freewheel and they said yes.

Then I came here and you just "stop my party".

Just to learn more you said that "If you are putting a lot of shock load into a hub, definitely avoid freewheels and go with freehubs with cassettes" but that's subjective. Can you please give some examples of what you consider "lot of shock load"?

Then Joe said "So with a 28 teeth", but why? Why it have to be 28? Why not 42? You are right with one thing even with a 36t cog I will not get that 28-34 combo using 4X T chainrings, not even a 38T, but that's a price I will be willing to pay (even when my knees don't agree), the rest of the numbers came very very close to what I use right now.

Anyways with that 10 speed freewheel I can only save the back wheel/hub. I still have to change the rest of the components. So there is the cost factor. Lets see for how much can I get a 9 speed bike.
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#10
These extra wide freewheels also require that you have more space in your frame. They are intended for people who use electric assist bikes - very easy going, big wide low pressure tires, often with suspension. The 8 speed freewheel has another 6 mm longer of unsupported axle.

I have seen 5 and 6 speed freewheels with bent axles......and even though I am a really heavy guy, I have had no issues over many thousands of miles with 7 speed freewheels. I never curb hop, always raise up for bumps, etc.

You can do whatever you want, but most of use VERY STRONGLY recommend going with a cassette.
Nigel
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#11
Nfmisso Thanks your feedback is very appreciated and well taken.
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#12
Well the 28 tooth chain ring was considering that you want some lower gear ratio to climb and start the calculations at some point, showing that the gear ratios you want will not be available with only one chain ring (by far!). That's all. To ride around town where I work I have an old bike that I stuck in one gear. I have to check the ratio, but it is... ok for me. I always wanted to get a clamp on down tube friction shifter to change this, but I cannot be arsed at the moment. It works good enough. My knees complain a bit when going uphill, and I cannot pedal fast enough downhill, but it brings me from my office to the lecture hall on the other side of town.

The 10spd freewheel is an interesting find! I didn't know these existed.
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#13
What you want to do is possible, but by the time you've bought a new chainset, rear wheel, cassette, front shifter, rear mech, cables and possibly a new bottom bracket it will likely cost more than your bike is worth.

You might be better off, selling your bike and buying a 27 speed (3x9) and then removing the front mech, shifter and a couple of chainrings or possibly buying a bike with hub gears.

And just to reaffirm what Nigel said, freewheels are rubbish. Back in the 80s, before cassettes were available and when I was considerably lighter than I am now as a full grown adult, I bent and broke dozens of rear axles.

What are you trying to achieve? Why do you want a single chainring?
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#14
Yep from the beginning, it seems that I should get a new bike. I know I'm not supposed to use it off roads, is a "comfort" bike after all, but for some reason I keep using once in a while at a fire road close to where I live. Nothing very technical though, with big rock drops and that kind of stuff. It is basically a 10 mile trail with flat dirt terrain with some steep grassy climbs at a margin of a small river, sometimes it gets bumpy on the uneven rutted terrain, small roots, gravel, that kind of things, but again nothing extreme. The change of tires to Kenda Cross and the Thudbuster, was of big help. The point is that this bike has never fail me, just the typical occasional flat tire and the needed cable adjustments. I wanted to remove the front derailleur and chainrings for convenience, less maintenance, easy shifting (just the rear), and because I use only 8 or 9 combinations with what I have right now.

[Image: creek1.jpg]
[Image: creek2.jpg]
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#15
Quote:I wanted to remove the front derailleur and chainrings for convenience, less maintenance, easy shifting (just the rear), and because I use only 8 or 9 combinations with what I have right now.

OK, I sort of get that, but to be honest, front mechs aren't usually that much hassle and don't require much maintenance. As for being a comfort bike, it's not that much different to a hardtail MTB and is probably more than up to the task of some light off-roading.

Some of the newer MTBs are showing up with 1x10, 2x10 and SRAM have a 1x11 drivetrain in the pipeline:

http://www.bikemag.com/gear/srams-1x11-group-new-details-emerge/

However, because they are fairly new systems they are generally restricted to Shimano and SRAM's more expensive components.
Also, the jury is still out on the efficacy of these new drive train set-ups. I watched the Olympic MTB cross country race and there were still plenty of competitors riding 3x9 set-ups. Good enough for a world class rider, good enough for me. Smile
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#16
Another advantage of 7, 8, 9 cassette is that the chains are stronger. I am noticing that 8 speed chains wear faster than 7 speed chains - but with my mass, I exert a lot of force on the chain.
Nigel
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#17
Quote:I am noticing that 8 speed chains wear faster than 7 speed chains - but with my mass, I exert a lot of force on the chain.

Are they the same brand/quality? There's quite a lot of variance in the quality/durability of different chain brands:

http://www.cantitoeroad.com/chains

But with regards to different widths of chain, I'm going to disagree with you, again. Smile

To make different chain widths, only the roller and the pins are different widths, the side plates are just as thick and with modern bushingless chains the amount of bearing surface within different width chains is not significantly different. It's a myth that chains "stretch", the side plates don't stretch, but the bearing surfaces wear, so the overall length of the chains increases.

http://sheldonbrown.com/chains.html

Up to 9 speed cassette sprocket and chainring widths are not significantly different either. There's only 0.07mm difference in the thickness of a 6 speed and 9 speed Shimano cassette sprocket. So, no real difference in wear rate due to thickness and you can run a 9 speed chain on a 6, 7 or 8 speed cassette without any problems. It's only when you get to ten speed that things change.

http://sheldonbrown.com/cribsheet-spacing.html

One thing that does have a significant effect on wear rates is the number of teeth on the sprocket, and chainrings, those little 10, 11, 12 and 13 tooth sprockets wear much quicker than the larger ones. So if you want to set up something like a single speed for durability, you'd be better off with something like a 44t chainring with a 18t sprocket, than a 30t chainring with 12t sprocket.
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#18
Hi again,

Ok it is given that I wont make the changes original intended but, I still want to do a couple of things.

1st I will like to remove the chainrings/cranks. Not to replace them but for other cosmetic reason I have in mind. I was able to remove the nut screws from both cranks but after that what?

[Image: cranks2.jpg]

Do I have to pound it with a hammer until it came off? Is there a tool to do that without damaging it?

Also I want to change the shifter, brake levers and cables from twist to thumb:

Shimano revoshift and Tektro levers
[Image: shifter2.jpg]

I found this one that includes the cables:

Sunlite Integrated shifter V-brake lever

Is that at least equal to the current one in terms of quality/performance?

Do you have any other suggestions for less than $25.00? It doesn't have to be integrated.

After this changes I will not make any other upgrades to this bike and will be looking for a new one keeping this one as a backup or for another person to come and ride with me.
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#19
To remove the cranks you need a crank extractor like this:

[Image: 859.jpg]

It's worth getting a decent crank extractor/puller, they fit the threads better and work better than the cheap ones. I have a genuine Shimano one and it works really well.

Together with an adjustable spanner, or 14mm open ended and a 17mm (I think).

You get them off like this: http://www.parktool.com/blog/repair-help/crank-installation-and-removal-square-spindle-type

The lever/shifters should work OK, but you could probably get separate shifters for less and use them with your existing levers.
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#20
I get what this guys saying, if you run in extremely ruff terrain, especially a lot of rough downhill spots, ditching the FD for a Chain Guide is a good idea, I think what you're looking for is an entry level dirtjumping/fourcross bike, you can find old kona cowans and shreds... really every company has made atleast 1 model Hardtail with chainguide and bashguard.

If you ditch the front derailler you definitely will need atleast a bashguard or you'll lose the chain constantly, bashguard + Chainguide is best if you're going through really rough stuff. Honestly Raleighs will disintegrate if you ride rough terrain, things like the crank, derailleurs, brakes, wheels(hubs and rims) and fork will never be able to keep up, you're much better off with an entry level trek, kona, giant, specialized, gt, ironhorse... etc, just not raleigh, ccm, dyno, anything they sell at wal-mart, k-mart or canadian tire. No offense meant to you or your bike, it's just I think those bikes are dangerous to ride off-road, and not really worth sinking any cash into. You can get a good used bike for like 350 and do the mods you want for 45-145 depending on whether you want a bashguard or bashguard + Chainguide.

I Personally love my chainguide and bashguard but I ride downhill and dirtjump a fair amount with it, when you ditch the FD you definitely lose a lot of you're ability to climb those steep hills so if you ride the bulk of cross country definitely keep your FD.

As for cost of modding the raleigh you definitely can, about 50$ for the wheel 110$ for the crank(you'll need to change it to ditch the front derailleur, raleighs all come with riveted cranks), bashguard for 45, cassette for 35-100 depending on 9 or 10 speed. RD, from 65 - 180 depending on 9 or 10 speed, shifter, 9 speed right only Shimano Saint is about 95$, i amgine the 10s all come in sets, so atleast 150 for them, add it all up and you've bought 2 better used bikes off kijiji lol

PS please don't say I'm hating, It's awesome you wanna start mountain biking, i just don't want you to ditch the sport because crappy equipment = a crappy and dangerous time lol Oh, and if you had you're bike assembled in store make sure to give everything a good tightening, the last time i was in canadian tire half their bikes had the stems on upside down lol.

Edit: I just looked at your pic a little closer and realized you have a threaded headset, Be very diligent about rust, they have a tendency to slip so when you turn the handlebars to avoid hitting that tree one day... well as they say in south park "you're gonna have a bad time" lol
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