AirborneFolder

Hi all - hope forums are like I remember them (and not like ****** or facebook where someone asks a question and most response are just people saying "I have one of those")

I recently got back into cycling after a long hiatus. I'm mechanically inclined but have forgotten more than I probably knew in the first place.

I have a Davidson Impulse handmade steel bike from the 1990s. It came with a mish-mash of components (Sach, Ultegra, Campagnolo, etc). I like consistency and have purchased (rash, too soon, not enough knowledge) a full Dura-Ace 7400 series groupset, which is where I am running into problems.

Downtube shifters. No problem here. I'm missing a mounting screw but I'll source one.

Front derailleur. No problem here. The cranks were 3 ring Ultegra and I've switched to 2 ring Dura Ace with a DA BB and a DA front derailleur.

Rear derailleur. Here's my problem(s)

1: How long should the rear outer cable be? I know enough that these can be sensitive to cable length and entry. Is it enough that I ensure there is no harsh bend to the cable adjuster or is there a "must be 8" and no longer than 9" rule - I think an old GF had that one as I recall...
: Second question - will any current cable outer and inner work? If I can keep my current outer, fine, but I do need a new inner as there was a kink.

2: It came with Fulcrum Racing 7s with an 8 speed (8 rings) on the cassette. However the largest is 32t and I know that the 7401 Dura Ace rear derailleur is only good for 28t. So I need a new cassette. I am assuming that I can pick up any vintage DA cassette (yes, I know it's probably called freewheel...) as long as it isn't larger than 28t?

3: Rear spacing. I'm not a fan of these modern(ish) wheels on a 90s bike and want to switch to a period-correct set - which means shiny rims, shiny spokes, skinny tires. Am I better off just buying a used wheelset that I like that already has a >28t freewheel fitted?

icemilkcoffee 

2. It's called an 8 speed cassette. Freewheels have the ratcheting mechanism built in together with the cogs. There are almost no 8 speed freewheels. Cassettes are just a stack of cogs. Any Shimano or Shimano compatible HG cassette will do. There are millions of these on Ebay or Amazon. Just avoid the Dura Ace UG one which uses a spin-on small cog to lock in the rest of the cassette. That one is an older standard that is totally different from and incompatible with anything else.

3. I agree period correct wheels look much better than the generic black wheels on these classic bikes. Just look for one with Shimano HG 8-10 speed freehub. Avoid the Dura Ace hub with the previously mentioned UG cassette (unless you really, really want to get into that). Also avoid the later WH7800 wheelsets which uses the stepped spline freehub. That one only works with Dura Ace and Ultegra 10sp cassettes. And obviously avoid freewheel hubs (identified by the spin-on threading).

rccardr 

Rear outer cable should be long enough to make a nice, rounded curve. There are no hard rules there. New cable housing is always nice on a new build and it’s cheap.

You are correct, the 740X DA series is generally limited to a 28t max cog. This is somewhat dependent on rear dropout length, as I’ve had Cannondale frames that would not permit shifting larger than a 26t. You do not need a DA specific cassette, any Shimano or SRAM cassette will fit and shift just as well. If you have a local co-op, they may be able to provide you with a couple of cogs that you can mix with your own to come up with a 12-26 8 speed combination. It ain’t hard.

Assuming you want 130mm rear spacing on the new wheels, I’d place a WTB in the For Sale section here as well as on The Paceline. Shouldn’t take long to get some very decent offers as many folks have moved on to 11+ speed and the older wheels won’t work. Or, build your own (or have them built) to get exactly what you want, which is what I do.

Davidsons are geat bikes. Enjoy yours!

RiddleOfSteel

1. I aim for 11-12" of rear derailleur cable housing (from the cable stop on the chain stay) on all my bikes with traditional derailleurs. I've had issues with them being too short. Standard shift cable and cable housing works just fine. Stainless for the cables, and at least Jagwire Sport or better for the housing. Both Shimano and Jagwire have DIY cable kits, which work well and don't cost a ton.

2. Seconding the statement that if you are shifting 8 cogs out back, any standard Shimano 8-10/11-speed wheelset with accommodate this request, and 7400 8-speed cog spacing is the same as any 8-speed spacing from any other Shimano groupset. If you're shifting 7 speeds, then you have a freewheel hub option available to you, or the aforementioned 8-10/11-speed rear hub, just with a 7-speed cassette and a spacer behind it to take up the extra space. Are your shifters 7- or 8-speed?

I, too, have gotten 7400 to play with a 28T big cog out back, and that is definitely the largest I would go without resorting to edge-case options like a Wolf Tooth drop hanger/link or putting a 620x GS (long cage) rear cage onto a 7400 body for more chain wrap and perhaps a touch more tooth capability/flexibility. A "standard" 53/39t front and 11-28t rear setup should be easily doable with the stock 7400 RD.

3. I've put 130mm (8-10/11-speed) rear wheels in plenty of my vintage bikes and had no issue. 7400 130mm hubs even had tapered outer locknuts to accommodate 126mm-spaced frames that they knew their new 8-speed wheels would go into as their owners upgraded. Depending on color and overall desired composition, modern wheels either look appropriate or very inappropriate. I've had modern Dura-Ace C24 wheels on my former Impulses and with their corresponding groupsets, looked great. For a vintage build, I definitely keep the wheels looking vintage/appropriate.

AirborneFolder

They are SL-7401 so 7 speed...again a thing I didn't check when the guy had the groupset at the swapmeet. I guess I need to source an 8 speed set. Or I can use the non-Dura Ace Shimano downtube shifters that were already on the bike.

icemilkcoffee 

They make 7 speed HG cassettes too.

BTinNYC 

What paint scheme does it have?

RiddleOfSteel

Since 7400 derailleurs only shift properly with 7400 shifters (pull ratios matching), you'll have to go one or the other. Either find a 7-speed cassette to use on the newer rear hub or build/have built a vintage setup that can take a 7-speed freewheel or cassette; or pick up some 8-speed 7400 down tube shifters. Those 8-speed 7400 shifters are uncommon. More common are the first gen 7400 STIs (brifters), but it's pay to play. But you have an Impulse, so you're already in that game.

You can use any normal Shimano rear derailleur with the 8-speed down tube shifters you have (assuming they're R400's or 6400-era 600 in very light grey).

icemilkcoffee 

Hold on, the Dura Ace 74** rear derailleur has a different pull ratios than other Shimano RD's. In general Shimano 7-10 speed road RD's are all interchangeable, except for that Dura Ace 74**, and the Tiagra 47**.

jamesdak 

Here this might help to make sense of the old Dura Ace combo's. There's a nice little chart in the link.

https://www.sheldonbrown.com/dura-ace.html

jamesdak 

Just an unsolicited comments on the wheels. First off, I get the sentiment of running period correct silver rims and how they look. That said, after having 3 or 4 set's of wheels on my Impulse over the time I've had it the bike just feels best out on the road with the more modern Campagnolo Eurus wheels on it. In fact even though this bike almost always makes it into my top 3 it's one I feel would be correct running anything from 6 speed friction bits all the way to the most modern rim braking kit. Sometimes I stay period correct with the bikes but the smiles per mile issue leads me to upgrade a lot of them.

Good luck with your choices though and we all are here to help.

reissue59

I run 7400, 7700, 7800 cranks.
7400 and 7700, i run 47, 48, 49 big rings, 39 small. If you have a clamp on front derailleur, just move it down a bit. For braze on , get a front derailleur extender .
i run 28 or 30 cassettes, even 32 with a woolftooth rear der extender

7400 and 7700, 130 generic rings are easy to find and wont ruin the look

RiddleOfSteel

This is exactly what I said in the entire first paragraph of the post that you just quoted from.

OP says he bought 7-speed 7400 shifters but has 8-speed DT shifters on the bike right now (that are not 7400 generation) and that those came with the bike.

AirborneFolder

Correct.
As Bought: Sachs front derailleur, Shimano 3 chainring cranks, rear ultegra 8 speed derailleur, 8 speed cassette on Fulcrum7 wheels, Shimano (non DA) 8 speed downtube index shifters.

Trying to get to (since I bought this DA groupset): DA front derailleur, DA cranks (2 chainring), rear DA 7402 8 speed derailleur, DA (7401) 7 speed downtube index shifters.

It seems the easiest is to procure a 7 speed cassette and mount it to the existing Fulcrum7 wheels/hubs. That saves me from having to buy an 8 speed cassette AND DA 8 speed downtube shifters and a new (old) wheelset.* If I go with an 8 speed cassette (have to replace the current one as it's too large) then I have to also buy 8 speed downtube shifters.

So if I buy a 7 speed cassette do I need any kind of spacer rings? It seems to me that it would be smaller (not as wide in other words) but I'm not 100% on that - just a guess.

*the DT shifters that came with the Ultegra are Shimano SIS 8s SL-R400. If those work with the DA 7402 rear derailleur then I can keep them but from reading above they aren't going to work with my DA derailleur.

smd4

Nothing to add, except excellent choice to go all Dura Ace. One of the nicest groups ever, for sure. I agree with you on the "consistency" statement. I hate a mish-mash of parts.

Oh, and I'd agree with 11" or 12" cable housing at the rear. Just make it a nice bend with no kinks from the cable stop on the chain stay to the adjuster on the derailleur.

Rick_D

IDK if I can help, but have a Davidson Stiletto from that era, bought new from Bill himself. It came with full Dura Ace, 2X8 freehub setup and indexed downtube shifters. The wheels were DA hubs and grey anodized Campy Omega 32H v-section rims. Quill stem is a Richey.

Good luck with your project!

AirborneFolder

I found this on Marketplace. Not sure if he'd ship but wondering if this Suntour Winner 7 speed freewheel would work with my DA 7400 series derailleur and the 7 speed downtube shifters?

Vintage Dura Ace Tubular Wheelset

wheelset Glued once
No brake track wear
Super light Double butted spokes to matrix rims
Suntour winner 7 speed freewheel Dura Ace skewers

icemilkcoffee 

According to Sheldon Brown's cog spacing crib sheet, the Suntour 7 speed freewheel should have the same cog spacing as the Shimano one. So it should be compatible with you Shimano 7s shifter and derailleur.

Just make sure you really want to deal with a tubular wheel/tire.

rccardr 

Have you tried using the 8 speed cassette you already have and shifting just the first 7 cogs with the DA shifters and DA RD?
If the second-to-largest cog is 28t or fewer, then the big one will just act like a giant spacer since you won’t shift into it.
The difference in cog spacing between 7 and 8 speed is .2mm, so if set up with perfect spacing in the 4th cog, it would only be off by .6mm at either end, which may not even be noticeable.
Or it might be terrible.
Wouldn’t know without trying.
And would buy you some time to find exactly the stuff you want while still being able to ride.

Rick_D

Mine measures 10.5+ inches. You want compressionless housing intended for index shift systems.

Piff 

I've used a Suntour Winner pro 7-speed freewheel with dura ace 7400 shifters/derailleur and it was okay. Not perfect, but good enough.