bowlofsalad

Hello,

I am switching from a 9 speed cassette to a 6 speed cassette. I've found that I need to get a new chain and shifter because of the cassette size change, but that leaves me wondering about the derailleurs. I am guessing I need a new rear derailleur, but I don't really know about the front derailleur. I suspect that the front derailleur might have been designed for specific chain widths, it seems far fetched in my mind, but I don't really know.

https://postimg.org/gallery/6jr43ccy/56423c15/ These are some pictures of the derailleur and rear fork (reference for mounting).

To summarize, when switching or changing from a 9 speed rear cassette to a 6 speed cassette:

1. Do I need to replace the front derailleur?

2. Do I need to replace the rear derailleur?

3. Would anything else need to be replaced? Such as the front crankset.

I am not very familiar with bicycle hardware. Perhaps a few recommendations, if necessary, may be made if you happen to know of a suitable part or two. I am sure to some degree, this question has been answered before. Forgive me if it has, many of the search terms I used gave me a lot of aimless and seemingly random results. Thanks for reading.

spectastic

Disregard...

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wait a minute... you have a shimano FD, but a sram RD?? I'm guessing you have sram shifters? are they compatible with shimano's FD?

wait is that a mountain bike?? ok nevermind then. . .

Mobile 155

You have some other considerations. The six speed chain is wider so you more than likely will need new derailleurs. The Chain rings on the 9 speed is thinner so a wider one will work better with a six speed. I am not sure the six speed will fit on a nine speed hub. There is a difference between a freewheel and a free hub. So you are looking at Shifters, Chainrings, (more than likely just as easy to get a new crankset.) new rear hub,(or wheel) I honestly am not sure a six speed chain will clear a 9 speed derailleur so I am guessing new derailleurs.

bowlofsalad

I am not entirely sure I understand what you mean by other considerations. Either way, it sounds like a spicy meatball, lots of stuff to replace. I guess I'll either try and figure it out with another 9 speed cassette or take the bike to a bike shop and ask for a bunch of replacement parts.

Thanks for the response.

IthaDan 

Why?

ThermionicScott 

Sure you're not switching to 7-speed? I don't think anyone has made 6-speed cassettes for years...

More helpfully, if you're using friction shifters, you shouldn't have to change anything else.

Homebrew01

+1

BlazingPedals

I've never seen a 6-speed cassette. A 6-speed wheel uses 127mm dropout width; so you'd need a new wheel and you'd need to re-space the frame. Also, you'd probably need a new crankset with more space between the rings - otherwise the chain will rub on the big ring when you're in the small one. You may also need a new front derailleur, otherwise you'll be trimming continually to keep the chain from rubbing on first one side then the other. Good luck finding indexed 6-speed shifters; friction shifting (non-indexed) might be easier.

digger531

I don't know if you can find a six speed cassette either but if you are using friction shifting it will work as is, more than likely. All chains have the same inside dimension the difference is the thickness of the plates so if there is a problem it would be the chain falling between the gears but I am fairly certain it will work.

bowlofsalad

I am 100% certain it's a 6 speed, zero doubt about it, they still make them. I am just going to order a 9 speed cassette and try and spread the rear drop out to fit. The frame is made out of chrome moly, I was able to pull the drop out apart by hand to what looked like far enough. The difference in space needed between 6 speed and 9 speed is 8mm, which is a super small amount of space. I am saying 9 speed is 8mm wider than 6 speed.

Changing everything over to 6 speed seems like such a freakin hassle, I am likely to come out with lower quality components and it is likely to end up costing more. I was wondering earlier why there are so many different widths of bicycle chain. Maybe there is a sacrifice in longevity when using a thinner chain for something such as a 10 speed, or something that effect. I am likely to go back and forth on 6 vs 9 speed in my mind. There are pros and cons to both sides for myself. Changing out the parts seems like a hassle, but that's mostly because I am totally unsure of what parts to get. Hopefully my LBS will have some solid guidance.

hueyhoolihan

i think some posts may be correct about the unavailability of a six speed cassette. six speed freewheel? yes.

BTW, if those of us that disagreed are correct (and my apologies if i am wrong) about the availability of a six speed cassette, it IS possible to put six hyperglide cogs on a 8,9,10 speed freehub body and fill out the missing cogs with spacers. if you use the same width spacers and cogs as were designed for you rear derailleur it should be okay with it (unless it's electronic!) as will your FD and chain. you may want to adjust the high and low limit screws on your RD accordingly. OTOH you may be less than satisfied with your shifters unless they are old-fashioned friction type. good luck.

for others... feel free to pick away at my recommendations. i don't want to take the time to BF forum foolproof this post. i promise i won't complain. really.

Myosmith

Cold setting a chrome moly frame to fit a modern wheelset with 9sp cassette will save you a lot of hassle as there are lots of 9sp components available at reasonable prices in every bike shop, bike coops, etc. There are instructions online for making a good spreader using threaded rod, nuts and washers. I think Sheldon Brown discusses it on his site as well. You might have to get a BB with a longer spindle to realign your crankset with the wider rear wheel. The project will be easiest if you use friction shifters or stick with all Shimano or all Sram for the shifters and derailleurs. Start mixing brands and you may run into compatability issues.

Posting some photos of the bike along with the make and model would help you get more specific advice.

spectastic

ok because it was mountain bikes (and not road bikes), I thought it would be different. But apparently the only difference is the tire thickness.

They do make shimano compatible cassettes for 6 speed. But the gears are spaced out like 7 speed cassettes, so you would need a spacer. The drawback with spacers is that you might end up with a cassette that isn't perfectly perpendicular to the hub axis, resulting in a wobbling cassette. But if you're dead set on using a 6 speed cassette, use metal ring spacers, not the plastic ones. The plastic spacers can bend fairly easily, and cause more wobbling.

If you want to save money, just buy a 7 or 8 speed cassette and save yourself the trouble. Hell, I doubt a 9 speed cassette would cost that much more.

BlazingPedals

Isn't a road 9-speed 130mm wide? That would only be 3mm of spread. The important part, as I understood, was to make sure the dropouts were parallel again; otherwise you risk bent/broken axles.

As I remember, there were a couple of flavors of 6-speed. One was one cog wider than a 5-speed, one used 7-speed spacing to fit 6 cogs into the space formerly occupied by 5. The latter, dubbed 'ultra-6' was able to use 5-speed wheels and frames.

bowlofsalad

I am not very good with terminology. I am sure it makes a world of difference to many. When I say cassette, I might have used that interchangeably with words like cogs, freewheel, freehub and so on. Whatever it is, it's got 6 speeds, I think it screws on.

The bike is a recumbent vision R54. It has a 135mm rear drop out. The guy at my LBS suggested just using the 6 speed gearing on the rear wheel and change nothing else (I assume I'd have to change the shifter). He seemed to think it would likely work out, if shifting isn't great, I'll probably try and get the 9 speed gearing.

He also spoke against spreading things like drop outs. A lot of people seem to see it otherwise though. The hassle to changing everything over to a 6 speed setup surely would be a pain. I like the idea of just using the 9 speed setup with 6 speed gearing on the rear. I don't particularly love the idea of spreading the rear dropout. Thinking of cracking a weld doesn't sound amusing. All this leads me to hope I can just stick with the 6 speed.

https://postimg.org/gallery/3qfmskgw/c203eec7/ Pictures.

I didn't really know there were classifications of shifters beyond their 'style', such as twist or something else.

Would this (https://postimg.org/gallery/ic346n6/210dcf86/) shifter be suitable with a 6 speed? If not, maybe https://www.amazon.com/Pyramid-Thumb-...iction+shifter one of these will be suitable, I like this set on amazon because they seem like they might take up a very small amount of handlebar space, something I might not have a lot of.


Thanks a bunch guys.