Shimano Megarange 7spd freewheel compatibility

Howdy.

A budding mechanic here. I have a ~1990's Bianchi Boardwalk hybrid whose freewheel I'd like to upgrade from its current Shimano HG-37 7-speed 14-28 to a Shimano Megarange 7-speed HG-50. This is what I know about my bike:

Chainring: Suntour Powering 48-38-28
Freewheel cogset: as listed above HG-37
Dropout spacing: Well, my cheap ruler says 129mm, but I'm guessing that's really 130mm (or is it possible it's 129.....?)
F/R Derailleurs: Unknown make/model. Identifying markings long gone.
Dropout type: vertical

I'm confused about a couple of things:
-According to Sheldon Brown's website, the Megarange 7-speed (and most other 7-speeds) is for a 126mm spacing. And 130mm spacing is typically for >=8. Why, then, do I have a 7-speed freewheel on a 130mm spacing?
-Is it true that not only must I have a 7-speed rear derailleur, but one specifically able to handle the 34T on the Megarange? If so, can someone suggest a rear derailleur which I might use, given all the other specs I've provided?
-Is a rear derailleur dedicated to a certain number of speeds or can it typically handle a range (e.g., does "9-speed" mean "up to" 9 (but including 7 and 8) speeds?
-If I haven't provided/considered all the specs needed to decide on this freewheel (and, potentially, rear derailleur) can someone recommend a 7-speed freewheel cogset which would improve (as in 13 or 12 T) on my 14-28 and be compatible with my current setup, i.e., so's I don't need to change anything but the freewheel cogset?

Thanks

Peter

There are no speeds in a derailer,but it has to be compatible with the shifter as to pull/throw ratios. It also has to more importantly be able to shift a 34 cog, which a number of current shimano mtb and hydrid RD do. If you hub has stndard freewheel threading, the megarange will work, even tho 7 speed is generally considered 126 dropout spacing on road bikes, mtb and hybrids use 135 and road bikes were even made with spacing wider than 126 and 7 speed freewheels. The actual spacing is in your hub and is the locknut to locknut distance. Are you looking for higher or lower gears or both, aas sram may offer a 12x28 in a 7 speed.

Most important is higher, but a lower bottom wouldn't kill me either. Couldn't find any SRAM 12x28's online--doesn't mean they don't exist, just couldn't find 'em. I got most of what you said. Based on your comments, would the cogset currently found at http://cgi.ebay.com/ws/eBayISAPI.dll...672786359&rd=1
fit? [It's described as a Shimano HG-50 7-speed freewheel 1330]Sure seems like it. And if I can avoid a derailleur change, all the better.

Thanks.

Peter

Have you tried performance or nashbar for freewheels? the ebay seller describes it as a freewheel casette.It cannot be both. It looks like a hyperglide casette with lockring ro me.

Thank you again.

Somehow an earlier reply of mine didn't get posted. In it I:

- speculated that the eBay item is indeed a cassette and not a freewheel, and
- realized that SRAM used to be Sachs, and that Sachs did indeed make a bunch of 7-speed freewheels, one of which was a 12-28. Can find 'em at bikepro.com, but will maybe hang and see if I can get one on eBay.

The learning curve continues....

Peter

I will follow this topic with interest as I have a Merida Kalahari MTB with continental slicks, 26x1.3, and need higher gearing.

Front: 28/38/48
Rear: 7 speed 14-28 with 130mm between the stays.

I think the ideal for me would be 12->26 with the smaller wheels.

Lets wait and see what you guys come up with.

cheers
George

__________________
Cheers,
George.

I'm currently renovating an old 70's-era 27" 10-speed that's been carefully "stored" under a tree in my mom-in-law's back yard for the last twenty years. Needless to say, nothing much is left beyond the frame.

Since I'm no longer the vigorous teen that road this bike in its better days, I'm leaning toward the following configuration:

39/53 double chainwheels, 14-34 7-speed Megarange freewheel.

My reasoning is that, with the big 53 chainwheel, cogs smaller than the 14 will be of little use to me, and lacking the "granny" wheel of a triple, my middle-aged legs will appreciate the big 34 on hills.

I'm hoping that this combination will give me decent cruising on the freewheel's "normal" 6 speeds, plus the "bail-out" capability of the 7th.

Does this sound like a reasonable plan, or is my ingnorance leading me to disaster?

Make sure you use a derailer that will shift a 34. Rust may have rotted the frame from the inside. You can find old bikes at garage sales and threft stores for cheap that have fewer issues and big rear cogs. Many old freewheels had 32 to 34 teeth.

I picked up a Deore LX derailer that can handle the Megarange. The frame appears OK -- I've stripped off all the old paint and I haven't found any obvious weaknesses. Except, that is, for the fact that the seatpost is permanently stuck in the seat tube. I suppose that could be a warning sign. No amount of penetrating oil has managed to free it, and, frankly, I'm not interested in trying Sheldon Brown's trick of hacksawing it from the inside.

One concern is the need for long-reach brakes. The old Tourney center-pulls are rusted tight. I suppose I could find some exact replacements, but does anyone know if these will work with modern levers?

They work.

Has anyone used 650 road wheels with 8/9 cluster and changing the shifter and derallier?

__________________
Cheers,
George.

What?

If you read the original posting and my first post, this is a reasonable question. I have 559mm (26") rims and 650s are 571mm, there are plenty of old 650 wheels and gear clusters from Triathlon bikes around, just wondered if anyone has tried it?

__________________
Cheers,
George.

Why don't you put it in one question?What do shifters and derailers have to do with it. You can tell more from a gear inch chart about what you need than I can offer by guessing about what you need. You also have to consider rear dropout spacing, and hub width between road and mtb stuff.

I have found a suitable cassette in the new Shimano catalogue,
On Page 79,
Cassette sprockets availability chart,
CS-HG30-7I, 11-28

Oh and just for "boudreaux", 130mm.

cheers
George

__________________
Cheers,
George.