Bicycle Mechanics - custom machining a shimano HG freewheel to fit 120mm spacing

I have been thinking about this for some time and a fellow forumite said he could try it.

the objective is to take a new HG Shimano 7 speed freewheel
MF-HG37 13-15-17-19-21-24-28
http://www.productwiki.com/upload/images/shimano_hg37_7_speed_14_28t_freewheel.jpg


and narrow it down to be 24mm thick 6 speed.
why???

I have 120mm spaced junior road bikes that are 5 speed- it would be great to built them to be 6 or possibly even 7.
yes I hear you -it sounds quite easy to respace to 126
or throw in an Ultra-6 suntour freewheel.

well I have tried it and the ultra 6 just does not work.
why?
a regina 5 freewheel is 25mm outside cog to outside cog,
the ultra-6 is 27mm
a junior road bike(JRB) has such a short distance between the bottom bracket and the rear axle that the chain just cant flex that much-
yes I hear you- I have tried a 7 speed, 9 speed and 11 speed chain.


I looked at an old 9 speed casette I had lying around and noticed that 6 cogs outside to outside are 24mm!
now the HG freewheel has the same thickness cogs
cogs are 1.8mm thick and spacers are 2.6
so a 6 speed with narrow cogs should be something like this-
1.8 x 6= 10.8
2.6 x 5 = 13.0
total is 23.8

HG body.
http://bellsouthpwp.net/k/a/kaeru41/Seven_Speed_HG-37_Body.jpg


the 7 speed,6 speed and 5 speed HG bodies avail are all 31-33mm wide assembled

this wont do- 27 is the max I can go on this.-it just wont fit.

idea is to mount it up on the lathe and turn off the threads, and make new deeper threads,
and new shims at 2.6 and see how it goes.

any thoughts on this project are greatly appreciated.
and then again if it does work I hope we can make more- even a narrow 7 could be assembled with just shim swapping
mike

Quasi Ultra 6 of 7 with the lock ring wider, instead of the 13 top cog?
and just using the lock ring to secure all splined cogs?
say 15~28t


What's wrong with 5 speed freewheels? that 6th cog
is why the width went to 126.

Sram/Sachs made a 2 cog 3 speed hub hybrid hub as a supplier
to Brompton

those are closer to a 110 .. so narrow and still wide hub flanges for lateral strength..
then you get a 6 speed setup. a half stepped 3 speed.
standard: a 13,15t combo..

You are going about it all wrong, and are probably working with hubs that are not in spec...

Dimension A = Freewheel Stop to End of Drive Side Locknut
Dimension C = Outside Lock Nut to Outside Lock Nut

[Regular Spacing]

25mm 5-Speed A=29mm C=120mm to 122mm
31mm 6-Speed A=35mm C=120mm to 122mm OR 125mm to 127mm

[Narrow Spacing]

27mm 6-Speed A=31 C=125mm to 127mm
32mm 7-Speed A=36 C=125mm to 127mm
36.5mm 8-Speed A=40.5 C=130mm is usually the case


All you have to do is shift 2mm of spacer/locknut from the non-drive side to the drive side of the existing hubs - redish the wheel and you're all set for an Ultra-6 / Narrow-6 freewheel on a 120mm-122mm rear hub.

To go 7-speed, chances are you need to go 125mm-127mm OLD (Dimension C) simply to keep asymmetrical dish from getting too extreme...

=8-)

its the distance between the cogs -that is the issue.
a narrow hub wont fix the problem, re shimming the hub wont fix the problem
this is a junior road bike w/ 24" tubulars
the distance between the BB and rear axle are much shorter increasing the chain twist

my thoughts are
the 5 speed is 25mm wide and works perfect.
the ultra 6 at 27mm did not work because the cogs were too thick(old fashioned) and the chain just did not like the flex at the smallest cog or the biggest cog.
modern chain did not help either

new HG teeth are narrow and if I could build a Ultra HG at 25mm running a modern chain it would be perfect.

Freewheel bodies are HARD, and don't take kindly to machining, let alone thread cutting. IMO, you'd have some serious heat treatments to go through before being able to pull that off.

If I were to try for your goal, I think I'd start with a freewheel that'd fit. Then I'd consider two different options:
1) outside help - find a guy with a water jet cutter, and a good stock of sheet metal. Have him cut new sprockets that'd fit the existing spline pattern out of a suitable thick plate. Then cut spacers on a lathe, assemble and ride. Bevelling the tips of the teeth is easily enough, but you'd have to do w/o the ramps.
2) the home shop approach - Pull the sprockets off a couple of scrapped freewheels. Disassemble a 9-speed cassette. Use a hole saw in a drill press to cut out the splined center of the sprockets from both cassette and freewheel. Might want to use a slightly smaller hole saw when you cut the centers out of the cassette sprockets to get a slimmer seam. Fit cutout freewheel centers to cassette outer sections. Weld/braze them together depending on seam width, available equipment/skill, and personal preference. Cut spacers on lathe, assemble and ride.

its the distance between the cogs -that is the issue.
a narrow hub wont fix the problem, re shimming the hub wont fix the problem
this is a junior road bike w/ 24" tubulars
the distance between the BB and rear axle are much shorter increasing the chain twist

my thoughts are
the 5 speed is 25mm wide and works perfect.
the ultra 6 at 27mm did not work because the cogs were too thick(old fashioned) and the chain just did not like the flex at the smallest cog or the biggest cog.
modern chain did not help either

new HG teeth are narrow and if I could build a Ultra HG at 25mm running a modern chain it would be perfect.

You are trying to take an Ultra-7 at 32mm and reduce it to a Ultra-4 at 24mm when what you'll really end up with is an Ultra-6 at 24mm THAT WON'T WORK BECAUSE AN Ultra-6 REQUIRES 27MM and a Regular-6 REQUIRES 31mm.

I'll say it one more time:

Your rear 120mm hubs are in all likelihood setup at Regular 5-Speed with a Freewheel Stop to Locknut distance of 29mm.

Move 2mm of spacer/locknut from the non-drive side to the drive side so that you have Freewheel Stop to Locknut distance of 31mm.

That way you will have a 120mm rear hub setup for Narrow 6-Speed. Correct the dish and you are set to go.

=8-)

you fail to consider the factor of cost and time.

you cant find a narrow freewheel body that accepts narrow HG splined sprokets
they were never made

cutting with a holesaw and brazing the center to another cog would take forever,and impossible to get perfectly centered and flat.

waterjet cutting 1.8mm flat plate will not get you the same quality long wearing teeth as a manufactured cogs- plus its not free.

an entire HG freewheel new costs 11 bucks-
the body is case hardened- only need to redo the threads which are not very much under load.
the spacers need to be turned on a lathe.

so when the cogs wear out (the only wearing part) just buy new off the shelf cogs

1. Spacer and Locknut change. 5 minutes labor.
2. The exact same Shimano freewheel (Ultra-7) can be had as Ultra-6 - same for IRD. 5 minutes online shopping.
3. Modern day 6/7 speed Shimano compatible chain. 5 minutes online shopping.

DONE!!!

Reference: Sutherland's Fifth Edition, p. 10-5, Sutherland's Sixth Edition, p. 10-6

=8-)

You are trying to take an Ultra-7 at 32mm and reduce it to a Ultra-4 at 24mm when what you'll really end up with is an Ultra-6 at 24mm THAT WON'T WORK BECAUSE AN Ultra-6 REQUIRES 27MM and a Regular-6 REQUIRES 31mm.

I'll say it one more time:

Your rear 120mm hubs are in all likelihood setup at Regular 5-Speed with a Freewheel Stop to Locknut distance of 29mm.

Move 2mm of spacer/locknut from the non-drive side to the drive side so that you have Freewheel Stop to Locknut distance of 31mm.

That way you will have a 120mm rear hub setup for Narrow 6-Speed. Correct the dish and you are set to go.

=8-)

I respect your opinion.

as I said- I can get the ultra 6 in there just fine, it will kind of work, but the chain angle side to side is too extreme on both the smallest and the biggest cog.

all the respacing will only improve the high or the low but not both
this is a junior 24" tubular bike.
I bought the ultra 6 because it does fit in 120mm spacing- but the distance between the bb and axle is much shorter then 700 wheels.

http://www.modernbike.com/itemgroup.asp?igpk=2126178463&TID=367&gclid=CPyCg_arjLICFcV7QgoddhgACQ

15.99

Chain is about 15.00-17.00

=8-)

I respect your opinion.

as I said- I can get the ultra 6 in there just fine, it will kind of work, but the chain angle side to side is too extreme on both the smallest and the biggest cog.

all the respacing will only improve the high or the low but not both
this is a junior 24" tubular bike.
I bought the ultra 6 because it does fit in 120mm spacing- but the distance between the bb and axle is much shorter then 700 wheels.


1. Wrong - FACT! I provided the Sutherland's Reference for you already.
2. 29mm to 31mm - that's only 1mm more per each side of the rear chainline centerline.
3. Respacing to spec does BOTH - see #2.
4. The short stays will always be a problem - and you'll always make it worse irregardless anytime you try to increase gears. Going Ultra-6 is not too bad - just 2mm. Going Ultra-7 at +7mm will be awful.

Pick your poison on #4.

=8-)

I wouldn't be surprised if someone else jumps in suggesting an IGH 8-speed - assuming one is available in 120mm or 126mm spacing.

=8-)

1. Wrong - FACT! I provided the Sutherland's Reference for you already.
2. 29mm to 31mm - that's only 1mm more per each side of the rear chainline centerline.
3. Respacing to spec does BOTH - see #2.
4. The short stays will always be a problem - and you'll always make it worse irregardless anytime you try to increase gears. Going Ultra-6 is not too bad - just 2mm. Going Ultra-7 at +7mm will be awful.

Pick your poison on #4.

=8-)

I tried to put in the falcon body-its 31mm and it touches the stays and I cant fix that.
shimano is slightly thicker.

regina5 -- ultra 6 --falcon-- shimano
http://i51.photobucket.com/albums/f394/rivieraproject/Childrens%20Racing%20Bicycles/IMG_6772.jpg

I was after only 6 cogs not 7 in a 120mm space

the ultra 6 at 27 was as far as possible with the short stays.

I have considered reshaping the big and small teeth on the ultra6 but it will never be the same as a modern hg cog set

i found a freewheel for 11 on th enet-its not worth arguing who has it for the cheapest price-
ok 11-15 bucks

You are confusing freewheel thickness with freewheel stop to end of lock nut dimensions.

27mm thick Ultra-6 / Narrow-6 freewheel on a re-spaced hub such that freewheel stop to lock nut = 31mm

PAY ATTENTION!!! Re-read the chart I initially posted for you...straight out of Sutherland's.

=8-)

(night)

OK I got the wheel in my hand..

Dimension A = Freewheel Stop to End of Drive Side Locknut
Dimension C = Outside Lock Nut to Outside Lock Nut


25mm 5-Speed
A=30.4mm C=120.4mm

campagnolo GS hubs.

-mike
(off to work)

you fail to consider the factor of cost and time.

I wouldn't say failed, I've just not done it.
How am I supposed to know what it's worth to you to get this done? Bike riding is a hobby, a deliberate choice. There's no specifiable "worth" to it.

Now, if you'd started your post with "I need to get this done in under one hour", or "I can't pay more than XX EUR/USD/GBP for parts" or something like that, then I'd left this thread alone.

We see it all the time. People build their own frames, wheels, bike lights, racks, have old generic frames sand blasted and repainted etc etc. Dead stupid things to do if you were to try to fit a price tag to them.



you cant find a narrow freewheel body that accepts narrow HG splined sprokets
they were never made

You're missing the point: take/keep the freewheel that'll fit the spacing, either custom make sprockets that'll fit the splines of said freewheel from sheet metal, or graft splined part from thick sprockets onto thin sprockets. Trim sprocket pitch to desired value by adjusting the thickness of the spacers.



cutting with a holesaw and brazing the center to another cog would take forever,

Again: How am I supposed to know what it's worth to you to get this done?

Although several steps, this is readily doable, w/o fancy shop equipment.

Forever - I don't think so. I'd need 3 jigs to hold the sprocket(s) - one hour to build those. Align-clamp-cut - I'd have the 1st set done in 30 minutes tops.
Brazing is slower, so I'd weld this. That's a 30 sec operation for each sprocket. Hardly worth counting, under the circumstances.

Including building the jigs, but excluding cutting the spacers, I reckon I could make one set in about two hours. For a batch build, time would drop dramatically.

... impossible to get perfectly centered and flat.

But you don't need "perfectly centered and flat". Ever looked at a cassette/freewheel wobble on its axis as the wheel is spinning? Getting it "good enough" seems well within reach.


waterjet cutting 1.8mm flat plate will not get you the same quality long wearing teeth as a manufactured cogs-
....so when the cogs wear out (the only wearing part) just buy new off the shelf cogs

So? Ever heard of something called a compromise?

But sure, if you prefer holding out for a perfect solution while ignoring possible workarounds, be my guest.
Wasn't this for a junior racer anyhow? Can't see wear rate being a critical feature there.


- plus its not free.
So?
Any attempt at solving this that doesn't rely on moving washers and/or redishing the wheel will have a definite cost associated to it anyhow. The amount is what should be important, not where it goes.

Water jetting is fast, once you've gotten the pattern worked out.
Doing one set of sprockets is probably scary expensive if you have to pay shop prices for it. But for a batch production, the cost-per-unit would drop right down.


the body is case hardened-

.. which you'd need to get rid of before cutting the threads, then back in to keep the serrated area where the pawls engage from getting chewed up. Good luck with that.


... the threads ... are not very much under load.

True. Aluminium bodies tend to do OK.


...the spacers need to be turned on a lathe.

So?
How were you planning to cut the threads? By hand? I see your whole scheme as relying on having access to a lathe anyhow, so cutting spacers is no bid deal.

"How were you planning to cut the threads? By hand? I see your whole scheme as relying on having access to a lathe anyhow, so cutting spacers is no bid deal."

I have friends with access to cnc machines, this would be a moonlight job.

older freewheels have each cog threaded on.
the hg freewheel type they are splined, just like casettes

of all the choices on how to do this -narrowing the body,
by cutting new threads for the locking washer
and making some spacers
is the most simple and repeatable method of doing this
all the wearing parts are replacable and off the shelf then.

"How were you planning to cut the threads? By hand? I see your whole scheme as relying on having access to a lathe anyhow, so cutting spacers is no bid deal."

I have friends with access to cnc machines, this would be a moonlight job.

older freewheels have each cog threaded on.
the hg freewheel type they are splined, just like casettes

of all the choices on how to do this
-narrowing the body,
by cutting new threads for the locking washer
and making some spacers
is the most simple,reliable and repeatable method of doing this
all the wearing parts are replacable and off the shelf then.

OK I got the wheel in my hand..

Dimension A = Freewheel Stop to End of Drive Side Locknut
Dimension C = Outside Lock Nut to Outside Lock Nut


25mm 5-Speed (correct)
A=30.4mm C=120.4mm (correct)

campagnolo GS hubs.

-mike
(off to work)

For Ultra/Narrow 6-Speed you need:

27mm Ultra/Narrow 6-Speed
A=31mm minimum, C=120-122mm OR 125mm-127mm (your call on OLD)

Narrow 6/7/8 speed chain required and re-dishing required....


=8-)

so you are telling me by moving one shim it will improve the chain/cog contact on both the high and the low??

OP

You really should grab a copy of Sutherland's Fifth or Sixth Edition...

On the pages I noted earlier, 10-5 / 10-6 under the "Hubs" section, the specs for the various freewheel widths are clearly spelled out. Furthermore, the specs for the freewheel stop to locknut on the hubs are clearly noted. You will also see that when the specs are followed - it in general establishes the centerline for the cogset - typically being the middle. A graphic is used on the noted pages to illustrate.

=8-)

Looks like you need to narrow it about 1/8 inch or so.......no thread cutting involved.After the gears get narrowed,an 1/8" or so of the spline will be showing correct?

You could surface grind about .020 thou off each gear to narrow it.Remove the theaded part and add a clip instead of threads to hold the gear pack together.Using the spines to our advantage,machine the spines for a clip,then using a belleville washer retained by a clip will easily hold the gear pack together.If you machine the clip in the correct place,you can set the side clearance tight using a belleville washer and it won't rattle.

You can always shim it if you don't like belleville washers.

It doesn't HAVE to be threaded,clips work in car and power transmissions,it should work on a bicycle trans also.

Looks like you need to narrow it about 1/8 inch or so.......no thread cutting involved.After the gears get narrowed,some of the spline will be showing correct?

You could surface grind about .020 thou off each gear to narrow it.Remove the theaded part and add a clip instead of threads to hold the gear pack together.Using the spines to your advantage,machine the spines for a clip,then using a belleville washer retained by a clip will easily hold the gear pack together.If you machine the clip in the correct place,you can set the side clearance tight using a belleville washer and it won't rattle.

You can always shim it if you don't like belleville washers.

It works in car and power transmissions,it should work on a bicycle trans also.

thanks booger- I think you understand the situation,

I believe making spacers to 2.6mm will narrow the cluster down fine,
then its the same distances as a 9 speed so I should be able to use a 9 speed chain with it.

the housing is too fat and is wider then the axle nut so thats why I need to cut it down.

a clip- sounds like a good concept to investigate.
with a 13t it get pretty thin at the nutted end.
the falcon has the last cog 13t threaded on so that would be a good locker.

these freewheels are cheap so if I muck one up Im not going to cry

Puch,

Why not space a 126mm HG hub down to 120mm and use 5 or 6 cogs with thin 8 speed spacers. Doing it this way will aloow you to place spacers on either side of the group of cogs to set your chainline.

I think he's having trouble fitting the inner body in 120,...he needs to narrow the whole body.Then respace the gears and spacers,then run a 9 or 10 speed chain.

I never tried,but I think you could respace down to 120 but you move the hub to the left 4-5 mm......not the best direction as far as wheel strenght goes and it's not helping your chainline any.You could shim the gears back out to help with the chainline after you narrow them,but then your back to threading the body again,and the wheel strenght still suffers some.

I guess you could run 9 or 10 speed gears also to give you some more room between gears,if you wanted to try and run 8 speed chains,but they are not so cheap....I don't own any 9-10 speeds......I think the gears are a little thinner but the splines are the same.

You also might want to look at the splines themselves from underneath.Are they solid or hollow.If hollow,your going to have an open slot when you machine them for threads or a clip.......not so good for bad weather....:)

You may have to sleeve the right side of the hub if the splines are hollow,so that you have some strenght,to block the weather and to support a clip or threads......it's starting to get complicated........spreading the stays is starting looking better all the time........

I never tried,but I think you could respace down to 120 but you move the hub to the left 4-5 mm......not the best direction as far as wheel strenght goes and it's not helping your chainline any.

Many of the older hubs have enough space on the right side allowing for 3 or 4 of rightward movement, then you'd remove another 2 from the left resulting a net movement of 2mm to the left. Yes, that would be 2mm of additional dish which shouldnt compromise wheel strength for the abuse an 8 year old is going to dish out. Chainline would be set by adding spacers to either side of the cog pack.

I think he's having trouble fitting the inner body in 120,...he needs to narrow the whole body.Then respace the gears and spacers,then run a 9 or 10 speed chain.
I think the gears are a little thinner but the splines are the same.

correct- the body is too wide to fit in 120mm spacing
correct the chainline is very tight on a 24" junior roadbike

the 9 speed has 1.8mm cogs and so does the inexpensive HG freewheel,
the tooth design is very simmilar.
by making 2.6 mm spacers I should end up with 24.8 cog to cog
that is slightly less then a narrow 5 speed.

unrelated but funny- the old 5-6 speed freewheels are so thick they take forever to wear out
these thin 7-8-9 speeds wear so fast and keep you coming back for more!

I think I'd use a Shimano 7 speed free hub and 9 speed cogs with the spacers thinned down enough so that a 10/11 speed chain will just fit between them.
Might have to thin down the smallest cog to use as a spacer only so the lock ring gets enough/proper purchase.

Cogs would then be EASILY changeable without a problem for different gearing options or replacement due to wear.
You'd have to rebuild the wheel for the new hub, but that seems relatively simple, considering the nature of your project.

A few years ago, when money WAS tight, I made an 8 speed cassette by using 7 speed cogs and thinned spacers.
I taped a sheet of emery cloth to the table and hand sanded each spacer.
X strokes, rotate a 1/3 turn, repeat.
Measure so all spacers are the same thickness.
Do it to all spacers and assemble cassette on free hub to get an idea how much more.
Repeat until lock ring seats properly.

It took about 2 hours at a semi leisurely pace. ( I worked slow and measured often)

As a side note, last year I got a bike that was factory equipped with an 8 speed. I tried my "custom" cassette and it worked BEAUTIFULLY!

I think I'd use a Shimano 7 speed free hub and 9 speed cogs seems relatively simple, considering the nature of your project.

umm I think freehubs are 130m spaced???

I would need to do a custom body on them also-i think they exist but only for the single speed boys.

all the wheel spacing in the world will not make the chainline good on both sides.

Sutherland's Fifth Edition, 1990, p. 10-5

Freewheel Clearance

-------------------------Freewheel Width----------Minimum Dimension A

Regular Spacing

5 Speeds.....................................25mm.....................................29mm
6 Speeds.....................................31mm.....................................35mm

Narrow Spacing (Ultra)

6 Speeds.....................................27mm.....................................31mm
7 Speeds.....................................32mm.....................................36mm
8 Speeds.....................................36.5mm..................................40.5mm



Quote:

"unrelated but funny- the old 5-6 speed freewheels are so thick they take forever to wear out
these thin 7-8-9 speeds wear so fast and keep you coming back for more!"

Regular 6-speed freewheels are THICKER than Narrow/Ultra 6-speed freewheels.

Regular 6-speed cogs are THICKER than Narrow/Ultra 6-speed cogs.

You understand why a Regular 5/6 speed chain is different than a Narrow 6/7/8 speed chain right?

=8-)

umm I think freehubs are 130m spaced???

I would need to do a custom body on them also-i think they exist but only for the single speed boys.

all the wheel spacing in the world will not make the chainline good on both sides.


Do you even have a clue what chainline is, what front chainline is, and what rear chainline is - and why rear hub specs exist in terms of rear chainline?

=8-)

umm I think freehubs are 130m spaced???

I would need to do a custom body on them also-i think they exist but only for the single speed boys.

all the wheel spacing in the world will not make the chainline good on both sides.

I'll mock up something for you tonight. Freehubs are available in 126 and if my poor memory serves correct the early, early versions may have been 120. Regardless, I'll mock up something with cog spacing less than 25mm for you to review.

umm I think freehubs are 130m spaced???

I would need to do a custom body on them also-i think they exist but only for the single speed boys.

all the wheel spacing in the world will not make the chainline good on both sides.

There were a lot of 7 speed free hubs with 126MM spacing on earlier mountain bikes.

I have had the bike in a very top-end bike shop.
we put on the ultra 6 and tried at least 5 different chains and checked the chainline.
the owner and I both agreed that it just wont work because
the distance between the BB and the rear axle is very short on a 24" junior
and I can also point out I do know what a chainline is.
http://businesscycles.com/graphics/chainline4.jpg

So this is what you do....

1. Find a threaded Shimano freehub cog and grind all the teeth down but leave just enough so that you can grab hold with locking pliers, vice grips or whater. This cog is you new lockring.
2. Obtain a Shimano 9 speed cassette with loose cogs...most modern cassettes have the cogs mounted on carriers which will not work. Choose the 5 cogs you want and their respective spacers. This is your new 5-speed cassette.
3. Looking at the hub below mount your custom made lockring and thread it on so its even with the freehub body.
4. Remove spacing from the right side until the freehub body hits the frame then add 1mm.
5. Measure the OLD. Remove spacing from the left side until your down to 120mm.

At this point I'll venture a guess and say your center to flange distances are within 1mm of the unmodified hub and I'll venture a guess and say the right center to flange distance is the same as any modern hub. What does all this mean? Simply it means you have 120mm spaced freehub that has normal dish.

6. Install your 5 speed cassette and move spacers to the left or right of the cogs to achieve the desired chainline.

Note: If your using HG cogs you'll need to grind off the wide spline. No big deal. Solid axle? No big deal, swap it to a hollow axle. Cheap hub? Gotta do what you gotta do. I read your previous thread, your daughter will never keep up with you on downhill runs...it's just simple physics, at whatever she weighs she has no potential energy.

http://i495.photobucket.com/albums/rr314/jimr2527/shimanohub.jpg

1. Find a threaded Shimano freehub cog and grind all the teeth down but leave just enough so that you can grab hold with locking pliers, vice grips or whater. This cog is you new lockring.

ok- i think i even have one simmilar to the pic shown.

2. Obtain a Shimano 9 speed cassette with loose cogs...most modern cassettes have the cogs mounted on carriers which will not work. Choose the 5 cogs you want and their respective spacers. This is your new 5-speed cassette.

got one worn out sram one right here for testing

3. Looking at the hub below mount your custom made lockring and thread it on so its even with the freehub body.

4. Remove spacing from the right side until the freehub body hits the frame then add 1mm.

5. Measure the OLD. Remove spacing from the left side until your down to 120mm.

At this point I'll venture a guess and say your center to flange distances are within 1mm of the unmodified hub and I'll venture a guess and say the right center to flange distance is the same as any modern hub. What does all this mean? Simply it means you have 120mm spaced freehub that has normal dish.

6. Install your 5 speed cassette and move spacers to the left or right of the cogs to achieve the desired chainline.

Note: If your using HG cogs you'll need to grind off the wide spline. No big deal. Solid axle? No big deal, swap it to a hollow axle. Cheap hub? Gotta do what you gotta do. I read your previous thread, your daughter will never keep up with you on downhill runs...it's just simple physics, at whatever she weighs she has no potential energy.

solid axles!!!
not on my bikes-skewers prevail in my kingdom!

I will look into this a bit more on thursday and friday.
I am stubborn with old tech(freewheels) freehubs is something completly new to me!

I have had the bike in a very top-end bike shop.
we put on the ultra 6 and tried at least 5 different chains and checked the chainline.
the owner and I both agreed that it just wont work because
the distance between the BB and the rear axle is very short on a 24" junior
and I can also point out I do know what a chainline is.
http://businesscycles.com/graphics/chainline4.jpg

If you spec a rear hub for Regular 5-Speed, and use a Regular 5-Speed freewheel, any chainline issues that occur will be due to the FRONT.

If you spec rear hub for Narrow 6-Speed, and use an Ultra-6/Narrow 6-Speed freewheel, any chainline issues that occur will be due to the FRONT.

Rear hub specs exist as published an noted for you for that very reason - it's an attempt to normalize the rear chainline thereby isolating the front - issues there are resolved by crankset type and bottom bracket sizing.

According to Sutherland's Sixth Edition, p. 4-31:

Shimano Freehub Cassette Hub

5-Speed Spline Length=23 OLD=120 or 126
6-Speed Spline Length=28.4 OLD=126 or 130
6-Speed Hyperglide C Spline Length=25.6 OLD=130
7-Speed Hyperglide C Spline Length=28.4 OLD=126,130,135

=8-)

My guess is MiamiJim is looking at those middle two for modification purposes...and possibly the third as well.

=8-)

Shimano Freehub Cassette Hub

5-Speed Spline Length=23 OLD=120 or 126
6-Speed Spline Length=28.4 OLD=126 or 130
6-Speed Hyperglide C Spline Length=25.6 OLD=130
7-Speed Hyperglide C Spline Length=28.4 OLD=126,130,135
=8-)

My guess is MiamiJim is looking at those middle two for modification purposes...and possibly the third as well.

=8-)

That is correct. I have a 126mm 7s HG I'm going to experiment with.

That is correct. I have a 126mm 7s HG I'm going to experiment with.

I have the 30.4mm non-Hyperglide C one as a 32h Deore LX FH-M550 with an OLD of 135mm if you think that will work too. It's free to the OP for the cost of shipping only. When customers abandon stuff...I don't consider it mine but rather as belonging to those who really need it.

Considering its age, the freehub body, mechanism, cones and bearings appear to be in excellent shape.

=8-)

I have the 30.4mm non-Hyperglide C one as a 32h Deore LX FH-M550 with an OLD of 135mm if you think that will work too. It's free to the OP for the cost of shipping only. When customers abandon stuff...I don't consider it mine but rather as belonging to those who really need it.

Considering its age, the freehub body, mechanism, cones and bearings appear to be in excellent shape.

=8-)
thanks-but I am dedicated to 36 holes-24" tubular rims are nt so easy to find anymore-especially in less then 36h

I have a set of 28h laced up to campy gs hubs and they are staying that way.
"let the pot stew for awhile before adding more salt"

umm I think freehubs are 130m spaced???

You can still buy 7-speed Freehub bodies -- they'd make for a 126mm spaced wheel. I wonder how much you could lop off the end of the body before you lose all of the lockring threads...

I would investigate taking a Shimano UG 5-speed freewheel, and making spacers to fit 6 cogs on it.
I built an Ultra-5 freewheel that way for a 1952 Christophe racing bike, but with 9s spacers (2.58mm iir) there shouldn't be a problem getting 6cogs on there. Total thickness would be only 23.7mm measured from the outside faces of the cogs.

The most important reason for using th Shimano freewheel is that you could then use the whole range of excellent UG cogs, for fully-customizable gearing. The Shimano sprocket ALL will work with 9s (and probably 10s) chain.

BTW, what knd of shifter is the OP wanting to use???

I would investigate taking a Shimano UG 5-speed freewheel, and making spacers to fit 6 cogs on it.
I built an Ultra-5 freewheel that way for a 1952 Christophe racing bike, but with 9s spacers (2.58mm iir) there shouldn't be a problem getting 6cogs on there. Total thickness would be only 23.7mm measured from the outside faces of the cogs.

The most important reason for using th Shimano freewheel is that you could then use the whole range of excellent UG cogs, for fully-customizable gearing. The Shimano sprocket ALL will work with 9s (and probably 10s) chain.

BTW, what knd of shifter is the OP wanting to use???

Have you followed the discussion at all "dddd"?

All he has to do is set the freewheel stop to locknut dimension on the rear hub to 31mm and then he's all set to use a Narrow/Ultra-6 freehweels - freewheels which are readily available online from Shimano and others.

=8-)

Look at the hub below and you'll notice it has overly thick lock nuts and cones. Assuming that hub is 126mm I'm very confident it can easily be spaced to 120mm by doing 2 modifications. First, your going to swap out the thick locknuts for thin locknuts and second your going to grind down the cones so they aren't so thick. This should get you to 120mm.

What your going to do now is accure a Shimano UniGlide threaded cog and buzz off ther teeth, this your lcokring. Next step is throw together a 5 speed cassette, I went inot my spare cassette/cog box and quickly put a 5 speed together that measure 22mm outside to outside. Once placed on the freehub add spacers to either side to set your chanline. The video below should give you an idea of what I'm talking about.

http://i495.photobucket.com/albums/rr314/jimr2527/shimanohub.jpg

http://i495.photobucket.com/albums/rr314/jimr2527/th_00001.jpg (http://s495.photobucket.com/albums/rr314/jimr2527/?action=view&current=00001.mp4)
http://s495.photobucket.com/albums/rr314/jimr2527/?action=view&current=00001.mp4

Look at the hub below and you'll notice it has overly thick lock nuts and cones. Assuming that hub is 126mm I'm very confident it can easily be spaced to 120mm by doing 2 modifications. First, your going to swap out the thick locknuts for thin locknuts and second your going to grind down the cones so they aren't so thick. This should get you to 120mm.

What your going to do now is accure a Shimano UniGlide threaded cog and buzz off ther teeth, this your lcokring. Next step is throw together a 5 speed cassette, I went inot my spare cassette/cog box and quickly put a 5 speed together that measure 22mm outside to outside. Once placed on the freehub add spacers to either side to set your chanline. The video below should give you an idea of what I'm talking about.

http://i495.photobucket.com/albums/rr314/jimr2527/shimanohub.jpg

http://i495.photobucket.com/albums/rr314/jimr2527/th_00001.jpg (http://s495.photobucket.com/albums/rr314/jimr2527/?action=view&current=00001.mp4)
http://s495.photobucket.com/albums/rr314/jimr2527/?action=view&current=00001.mp4

MiamiJim:

His goal is 6-Speed, NOT 5-Speed on a 120mm rear setup.

=8-)

...hence why I keep explaining to him the need to set Dimension A on his 120mm hub (freewheel stop to locknut) to 31mm and then using a Narrow/Ultra-6 freewheel with some minimal re-dishing of the wheel.

=8-)

MiamiJim:

His goal is 6-Speed, NOT 5-Speed on a 120mm rear setup.
-)

OK, so I'll add another cog....granted the freehub in my video is 126 but there's no reason 6 cogs wouldnt work with a modified hub.

http://i495.photobucket.com/albums/rr314/jimr2527/th_000032.jpg (http://s495.photobucket.com/albums/rr314/jimr2527/?action=view&current=000032.mp4)

Bumping this back to the top with a question for the OP:

The OP claimed he had tried a Suntour Ultra-6 freehweel, and stated that it didn't work. My question is:

"Does the freewheel body of the freewheel you tried say, "Accushift" on it?

=8-)

Have you followed the discussion at all "dddd"?
All he has to do is set the freewheel stop to locknut dimension on the rear hub to 31mm and then he's all set to use a Narrow/Ultra-6 freehweels - freewheels which are readily available online from Shimano and others.
=8-)

Not sure what you meant when you repeatedly referred to a freewheel stop. Is that what stops the freewheel threading in too far? I'm not sure that would be as important as how far from the inside of the dropout that the cogs are positioned, since the OP has a "chainline sensitivity" problem in addition to getting the 6sp freewheel to actually fit.

As for the "Narrow/Ultra-6 freewheels", Shimano never offered these, but the 5sp Uniglide freewheel is readily available and the spacers are plastic, so easily modified if one has a precision caliper.
The Shimano freewheel will also give the best friction shifting characteristics, and has the potential (because of the cog thickness) to perhaps allow narrower spacers than any Suntour freewheel could use.

As for modifying the locknuts, the wrench flats might go away, and the dust cap might be in the way of any wrench flats which are extended inward, but the cone and locknut could be torqued together on one side at least before doing the final axle cone adjustment on the other side of the hub.

If I had this problem, I would just go with the parts I have and do some test-fitting. There's nothing like having the parts in front of you, and you can usually just try different setups later as the parts become available.

If I had this problem, I would just go with the parts I have and do some test-fitting. There's nothing like having the parts in front of you, and you can usually just try different setups later as the parts become available.

exactly- this is why I came to the conclusion to modify a freewheel and make a nice tight 6 speed with modern teeth and a 9 speed chain.

have not started but it is on the list of things to do,
I can pick up a new freewheel anytime- but finding the cogs I want is a different matter.
13-14-15-17-18-20-22

Not sure what you meant when you repeatedly referred to a freewheel stop. Is that what stops the freewheel threading in too far? I'm not sure that would be as important as how far from the inside of the dropout that the cogs are positioned, since the OP has a "chainline sensitivity" problem in addition to getting the 6sp freewheel to actually fit.

As for the "Narrow/Ultra-6 freewheels", Shimano never offered these, but the 5sp Uniglide freewheel is readily available and the spacers are plastic, so easily modified if one has a precision caliper.
The Shimano freewheel will also give the best friction shifting characteristics, and has the potential (because of the cog thickness) to perhaps allow narrower spacers than any Suntour freewheel could use.

As for modifying the locknuts, the wrench flats might go away, and the dust cap might be in the way of any wrench flats which are extended inward, but the cone and locknut could be torqued together on one side at least before doing the final axle cone adjustment on the other side of the hub.

If I had this problem, I would just go with the parts I have and do some test-fitting. There's nothing like having the parts in front of you, and you can usually just try different setups later as the parts become available.

1. Shimano HG 6-speed and HG 7-speed freewheels ARE Narrow/Ultra spec freewheels...5.0mm cog center to cog center spacing. So are 8-speed freewheels.
2. He doesn't have a chainline issue - he has a Dimension A (freewheel stop to end of locknut) and freewheel width mismatch.
3. He certainly does have very short chainstays - increasing gear count = increase chain angle of attack at the low and high ends - more prominent the shorter the chainstays.

=8-)