6-speed freewheel - larger cogs available?
 

I have a Specialize Expedition, produced about 1984 - with mostly original parts. It's a glorious heavy touring bike.
It has half-step gearing, and because I am getting older, I need to re-gear it once again. Previously, I retained the middle chainring and put
it on the outside (top gear chainring), then replaced the old middle chainring with a smaller gear (yet retaining the half-step). Then, I replaced the granny chainring with a smaller gear.

Currently, the gearing is:

Chainrings:

44-40-24

Cogs on freewheel:

13-16-17-20-24-28

Can you guide me to a freewheel produced to make the freewheel something like (and retaining my half-step + granny arrangement):

14-16-20-24-28-34

I am not particularly interested in the "megarange" freewheel," because I would like a more fluid transition, not a huge jump to a 34: I believe the mega is 14-16-18-21-24-34.

Will my short-reach derailer be able to handle this gearing?


Will my current Sedis chain work?


Will front derailer work?

suntour mountech
super champion wheel (36 spoke)
specialized hub
friction shifting (original - on down tube)

I have a photo of the freewheel if this would help.

Consider changing the middle chainring to a 34 or 36 and try that before replacing the freewheel. A 14-34 freewheel would require a long cage mountain bike rear derailleur.
Clean and grease the hubs, headset, bottom bracket, and pedals including new bearings where needed.
Remove any unnecessary weight on the bike.
Ride

His mountech might already be long-cage. But if not, a long cage mountech (or a Suntour VXGT or something) can be had on the "bay" for $10-30.

But yes, changing the middle chainring might be a good thing to try.

ird makes a seven speed freewheel that goes from 14-32, with no big jump (I think it's 28-32).

Yep,IRD makes one,32 big cog.If you really want a 34 gear,you could get a mega-range and buy 1 cog,then do some gear swapping.That's what I used to do on my old touring bike before I changed to a freehub.

If you are actually going to tour with it,try to stay with 6 gears if you can on a freewheel.With 7 speed,you run a liitle more risk of bending an axle.

Just to muddy the waters a little more,they made a wide(130) and narrow(126) six speed freewheel.As long as you have non indexing shifters,you can run either one.

First off, have you tried mega-gearing? If not, it may not be as bad as you are thinking. I've built up freewheels with bail-out big cogs and it usually works out pretty well. But I believe my biggest bailout jump has been 26-34 not 24-34. Personally I would just get the megarange and be done with it.

You may be able to get two Shimano HG freewheels and mix and match cogs (I do not have any experience with HG but I do this all the time with UG freewheels). If the splines are compatible, you could get 14,16,18,20,22,24,34 and 13,15,17,19,21,24,28 7-speed HG freewheels and put the 21,24,28 from the 13-28 in place of the 20,22,24 of the 14-34 to get 14,16,18,21,24,28,34. The most likely impediment to this is that the 20 is likely to be a small spline while the 21 is likely a large spline. In this case, building a 13,15,17,20,24,28,34 might work.

Oh, and most bikes that use a 6-speed freewheel are 126mm rear spacing and can take a 7-speed with no modifications (but some may need an additional 1mm spacer on the drive-side axle). But a 7 might be a problem if your FW is a Suntour Ultra-6 and your frame is spaced at 120mm.

Wild Vagabond ....

IRD makes 6 speed's in 14,17,20,24,28,32 and 14,16,19,24,28,34.

You'll need a new chain. Your Mountech should be OK . (It is a long cage, for those that don't know) I can't believe you still using yours...... mine broke not long after I bought my Stumpjumper back in '83 at Cosmic Cycles .


If you use a good gear chart, you'll see the Shimano 6sp megarange FW isn't so great for half step gears. I also use half-step gearing, so I'm very familiar with it. I wouldn't use that particular FW.
http://home.earthlink.net/~mike.sherman/shift.html Just put in your rings and the IRD FW cogs and you'll see either IRD 6sp FW would work OK.... not perfect, but the progression should be satisfactory on the road.

The Mountech is actually a wide range derailler, with a max freewheel size of 34T and able to wrap 40T difference: http://www.disraeligears.co.uk/Site/...erailleur.html

Freewheels with 32T or 34T large cogs should be readily available.

Garthr,
Thanks for the very useful information! I am still working on completely understanding your most excellent gearing chart. Nice work! Do you have a suggestion as to the best (as in shifting ease and durability) chain for use with the IRD 6 speed? It, the freewheel, must be different in some important way to make a different chain necessary. What is the difference?

I see there is someone nearby who might have one: Arizona Spoke
Flagstaff, AZ
928-773-8544

http://www.interlocracing.com/freewheels_steel.html

Cosmic Cycles? Did you once live in Northern Arizona?

http://www.cosmiccycles.com/

The gear chart is pretty easy to work with. Since the IRD FW's are not listed on the pull down menu, you can just type in the ones you have. While the chart is pure numbers, it is a tool to use to see what changing your gears may feel like. In half stepping, your jumps between gears can be 4-5 gear inches, this is essentially splitting a jump of the traditional what now is called "crossover gearing" (like 26-36-46 rings)

You'll only need a new chain because it will need to be longer with a 32 or 34t cog, and with this a new chain is needed.... as opposed to just adding some links.... which would result in the chain skipping. When you change the FW to completely new gears, it's always best to get a new chain. No special chain is needed, these days you'll see them labeled a 8 speed, 9sp, 10sp. etc. What you want is an 8sp chain, which works for anything from 5-8 speeds. The exception to this are the Suntour Ultra 7 FW's, which work best with a 9sp. chain, but you're not using those. I use SRAM PC-850 chains myself, they're inexpensive and work as they should. Installing them and taking them off is simple with the quick connect Power Link.

I spent some time in Flagstaff in 1983/84 while going to NAU. I bought my Stumpjumper at Cosmic Cycles. I don't remeber much about school, but I sure remember the great rides around Flagstaff on the Stumjumper! Great fire road trails. My favorite ride had to be going up Lookout Road to the TV towers in Fall. What a view... I'll never forget that . The Pine trees..... wonderful smelling pine trees everywhere.

Yes, there is a host of terrific riding around here, although I find the season too short. Of course, I do lilt down to the Sedona area as the bird bath freezes, prompting me to turn on the bird bath heater. It was 24F here about a week ago and my Sacred Datura (Moon Flower) is just starting to poke out (and, it's June!). I love hiking the Grand Canyon, and recently completed a hike of the entire Tonto (115 miles).
Anyway, I digress, thanks for the very useful gearing tool/utility and for the most excellent information and suggestions. Rob of the WV wildernessvagabond.com

I like KMC chains, they are low priced and durable. Niagara has a missing link version on sale right now for $9, otherwise, just get the basic KMC Z chain for around $5.

Careful. "Long cage" does not equate to being able to handle larger cogs. It has to do only with the amount of chain slack the RD can handle. Note that Al1943 said, "A 14-34 freewheel would require a long cage mountain bike rear derailleur." Key is the bolded phrase. The parallelogram geometry of MTB RDs is such that the shifting arc is steeper than for road RDs. This is what makes them able to handle the big 34T cogs.


Larger cogsets do tend to produce more slack, so may want a longer cage. But a "long cage" RD may not be able to handle the big cogs. The equation is not commutative.

A mountour is a mountain RD. In fact, it's the very first one. Many of the old suntour long cage derailleurs can handle silly large cogs. The VX GT can do 34, easily,

As noted above.

Success! My good friend, Stan, sent a FW to me, and a Huret DR. I finally removed the FW and installed this new FW, taking it on a 40 mile ride up the Mormon Lk "steps." It worked terrific, without chain or DR replacement. I didn't even need to adjust the DR. The new (used) FW is freewheel: 14-19-20-21-28-34

So, Currently, the gearing is:

Chainrings:

44-40-24

Cogs on freewheel:
14-19-20-21-28-34

"Old" (removed FW) cogs were: 13-16-17-20-24-28

Thanks for the help,