Vintage_Cyclist

On the freewheel spacing, sometimes there is a differentiation between freewheels of the same number of speeds and how far they thread onto the hub.

I was putting a 7 speed F/W on my Trek 760 (126mm spacing) and got a Shimano MF-T721 14x28 7 speed F/W. The chain couldn't ride the small gear, without hitting the seat stay. I pulled a F/W off another bike, a Shimano MF-HG37, 13x28 7 speed. This one worked fine. The fact that the small cog was one tooth smaller didn't account for the difference, it was the threading on the two F/Ws.

Before I put it on, I set the two freewheels on the work bench and laid a level across them and they were equal distance, front to back. There was, however, a difference in construction between the two that allowed the HG37 to thread on about 2mm further, giving more clearance for the seat stay. The HG37 is constructed like a vintage freewheel, where every cog is on the freewheel body. On the other hand, the T721 has the two largest cogs riveted onto the 5th cog, like outriggers. When threaded all the way onto a hub, it sits farther out.




The Trek 760 has fastback seat stays and the sharper angle was probably a factor here. I have the T721 on two other 126mm spaced bikes with standard seat stays and it works fine.

The T721 (brown/bronze) is made in China. I believe the HG37 (silver) is made in Singapore.

If you have another different F/W, you might want to put it on and see if it works.

seedsbelize 

Today I switched from 7 spd to six. I think I'll like it better. Of course it's not an Ironman. It's a lowly Trek.

RobbieTunes

Jeepers, math AGAIN!

texaspandj

@ Vintage_Cyclist that explains a lot and very useful to know. Thank you.

canklecat

Yup, what @Vintage_Cyclist wrote. That's why I use the dork disc with the original Suntour freewheel but omit the disc when I use a SunRace freewheel. Slight differences between the two, just enough that the dork disc acts as a shim with the Suntour, while the SunRace inner facing flange is thick enough to make the dork disc unnecessary. And the rear derailleur needs only minor tweaks when I switch between the two types of freewheels.

RobbieTunes

I'm having trouble wrapping my head around a dork disk as a shim. I've never seen one that affected the dimensions on the rear before. I've seen them clipped on in various places, but never as a spacer or shim.

Can you clarify this for me?

TXsailor

​​​​​​Can the power link for a Sram 850 chain be reused? I didn't clean the factory lube off mine and 75 miles later it's a gooey mess.I want to put it in my ultrasonic cleaner.

rccardr 

canklecat

I'll try to remember to photograph both the SunRace and Suntour freewheels, and original dork disc, next time I swap freewheels -- may be a week or so.

The dork discs may vary between Ironman models, or year to year. On my various other bikes with dork discs the discs were all dispensable plastic, with no function other than to protect the spokes in case the chain overran the freewheel or cassette on shifting with a misaligned derailleur.

But on my '89 Expert the dork disc is plastic attached to a metal inner disc. The metal acts as both a shim or spacer, and a lock washer, with the original Suntour freewheel. The dork disc doesn't just spin freely. When the Suntour freewheel is snugged up it locks into the metal disc, like a washer.

Without the disc the Suntour freewheel snugs up a little closer to the hub, requiring adjusting the rear derailleur. The SunRace freewheel has a thicker flange on the inner facing side toward the hub. It serves the same effective function as the dork disc, a spacer. So I can swap the two freewheels without needing significant adjustments to the rear derailleur.

If I leave the dork disc on with the SunRace freewheel, there's too much space between the freewheel and hub, requiring more adjustments to the derailleur.

The Suntour freewheel *could* function just fine without the dork disc. And the SunRace freewheel *could* function just fine with the dork disc. But swapping freewheels would require significant adjustments of the rear derailleur in index shifting mode. (Probably less critical in friction mode, which I'm using this year.)

Clear as mud, right?

Right now my 13-25 SunRace freewheel is on my Globe Carmel comfy hybrid errand bike, since it works better than the original Shimano MegaRange freewheel. I'm going to get a SunRace 13-28 or 14-28 for the Globe, then try the 13-25 SunRace on the Ironman again. I used the 13-25 SunRace briefly on the Ironman several months ago but didn't care for the spacing in indexed shifting mode. Now that I've switched to friction shifting the 13-25 might work okay. And I'll need a little extra help on climbs while I'm recuperating.

RobbieTunes

OK, I get it now. Thanks.

Classtime 

rccardr 

canklecat

Continental Ultra Sport II in 700x25 run very slightly wider (about 25.5) on my '89 Ironman Expert's original Araya CTL-370 rims. Plenty of clearance and a noticeable difference in comfort compared with 700x23.

However I didn't care for the handling with a 700x25 on the front. Felt just a bit squirmy on fast turns. There's just a bit too much tire hanging over the rims. So I swapped the front back to Schwalbe One 700x23, and kept the Conti USII on the rear for comfort. Good handling again and still comfortable on chip seal.

canklecat

Has anyone converted an Ironman 7-speed freewheel to 8-speed cassette wheel set? Did you need to re-dish the wheel, cold set the frame or any other tricks?

Asking because a friend gave me a set of pretty decent wheels with 622x14 rims that are currently on my hybrid. The hybrid really needs a slightly wider rim to take advantage of the wider tires I prefer on that bike.

But 622x14 would be fine for the Ironman, assuming the hub width is compatible. That way I could tweak the original wheels and keep riding. The original wheels need to be properly trued with the spokes tensioned, and I see the freewheel wobbling slightly as if the axle is warped. I plan to go over it with a mechanic friend who has a truing stand.

And I'm guessing the older style Shimano rear derailleur I'm using at the moment would handle an 8-speed cassette. There appears to be enough movement and room in the limit screws. However I'm not really concerned about making full use of the gear range, since the existing Suntour GPX shifters may not handle it. Mostly I'm curious to see how the wheel would do on the Ironman. It's a bit stiffer, higher profile and both wheels appear true without any hub wobble.

RobbieTunes

Look at any of my Ironman models. All use an 8/9/10 wheelset, except for the Not Your Daddy's, which uses an 11-sp wheelset.

So the answer is yes, it works, no re-dish, no cold-set. You will quickly develop the technique to insert that rear wheel. With more gears, be sure to use the axle adjusters, as precision is more important.

Some shifter/RD's will cover the distance of 8/9/10, some won't. Generally I match my R shifter to my RD.

RobbieTunes

By the way, folks, I'm thinking of converting a Paramount from 2x7 DA to 2x9 DA. This may well free up a set of DA 7-sp wheels, shifters, brake levers, and crankset. For an Ironman that wants to go fast.

canklecat

Hey, I might be interested, at least in the wheels. I really need to replace the original Araya CTL-370 set and get them some proper loving care and attention.

texaspandj

Im interested in what ever CC doesnt need.

canklecat

I'll attach some photos to this post separately -- I'm typing from my laptop but the photos are on my phone. It'll take a few minutes.

The wheelset is from a friend who was helping get my Univega working again. It's the bike I was riding when I was hit by a car in May. It sat in a friend's garage for months until I was able to retrieve it a couple of weeks ago. The frame is fine but the original single wall Araya rims (PX-45, I think) were warped. I'll salvage the Shimano Exage hubs from those wheels later.

The wheelset he gave me are Alex S500 double wall rims, 622x14, a nice looking functional set. The Univega really needs 622x18 or wider for my preferred tires, Continental Speed Rides (nominally 700x42 but measure closer to 700x38). The 622x14 rims would probably do nicely on the Ironman.

I didn't notice until a couple of days ago the rear wheel is offset. Finally occurred to me when I could not get the cantilever brake pads both aligned and with the smooth posts roughly equidistant. After an hour of wrenching and cussing I finally realized the entire wheel was offset in the frame. Interestingly enough, it rides just fine. I've ridden it several times, distances from 12-34 miles, no problems. But it looks funky. Dunno if it's potentially dangerous.

I'm wondering whether I could substitute thinner locknuts on the hub side opposite the drive side to balance the wheel a bit.

markwesti

Killin' some time on the web I was reading a Sheldon Brown page written by T-Mar . I have read this page before but because this time I was looking at it for different info I noticed that the Comp TA was made in 84' and became the IM in 85' because of the copy right infringement lawsuit . I had always thought the Comp TA was a 85' . ?

RobbieTunes

jjames1452 

I am going to need some help. I had a 56 cm Miami Vice Ironman that was a little small. I let it go to a fellow BF member. I am supposed to get a 60 cm red and white Ironman frame. Question, should this be built as a Suntour (Arx) or Shimano 600 build to get as close to original as possible. I will provide pics and the serial number when it arrives in a week or so .

Very Excited to get on an Ironman that fits!!!

texaspandj

Excited for you.
Depends on year and or if expert.
Btw if its suntour it would be GPX.

RobbieTunes

If it's red&white 2tone, it would be an 86 with 600EX, or an 87 Expert with 105 (1050).

if it's red&white fade, it's an 88 Expert, would still be 105.

(yer slippin' Tex)

RobbieTunes

we should talk.