rjhammett

I am building up a bike that has a Shimano 600/Ultegra 6401 rear derailleur. According to VeloBase this is from the 8 speed group. Currently, the bike has downtube friction shifters and a 7 speed freewheel. I am interested in changing to 8 speed index shifting if possible. The chain stays have a 126mm spread. So my question is can I switch to an 8 cog freewheel and run index shifters with the 126mm spread?

FastJake

Not unless you want to bend axles at an even faster rate. Also, 8S in 126mm makes for a really weak wheel. Better to stay with 7S in this situation unless you want to spread the stays to 130mm AND get a cassette freehub.

Right now I'm running a Shimano 7S cassette with 8S bar-end shifters with the "alternate cable routing" and it works great. If you're worried about shifter options.

zukahn1 

Simply answer no if it works good as a 7 speed leave alone. I state this again if it works good leave it alone. Changinging it to a 8/9 will reguire changing wheels, resetting changing the dropouts if possible and a lot of other minor stuff.

fietsbob

you need more frame spread 8 speed needs a 130 width or spoke tension imbalance ie dish is worse..
135 & 7 speed is good. as hub is dished less , not more..
but 135 and 8 speed is able to use stock wheels..
not custom modified builds.

NB: Its the Ratios , not the cog # count , that is the Gear..

7 useful ratios X 2 or 3 on the cranks is fine..

did many international bike tours on 7x3 bikes..

friction shifting derailleurs is a skill ..
index shifting is just a product.

(my index shifter lever operates a 3 speed IG Hub.

the Rohloff IGH does all that internally, as well ..)

bradtx

It's become a fairly common practice to install a 130 mm hub into a bike with 126 mm rear dropout spacing without cold setting. You'll need a 8-10S compatible freehub, a cassette, an 8S chain and shifters to convert from 7S.

Brad

fietsbob

just do the math, what gear ratio do you gain, and do you miss having that ratio.

7 speed freewheels start at 13t, changing to 8 (cassette) you might gain a 12t.

cs1

The late great Sheldon Brown recomended using a 9 sp cassette minus one cog on a 7 sp cassette hub to get 8 sp in a 126mm rear. He seemed to think it was fine. If I trust anyone it was Sheldon. Good luck

ThermionicScott 

If it's really a freewheel, I would stick with 6 or 7. If you want more speeds, you should upgrade to a cassette wheel.

rjhammett

It is a 7 speed freewheel on a silky smooth Suntour Superbe Pro hub. I would never replace those hubs to gain 1 speed with a free hub/cassette. I wanted to see if I could go to an 8 speed freewheel and if so I probably would.

onespeedbiker

If you do decide to replace your rear wheel, I'll take it off your hands real cheap! Anyway, you may be able to go with indexing very cheap, dpending on your freewheel and shift levers. The Shimano 6401 is STI rated meaning it will index with the right shifters; if your shifters are index capable, you simply need to turn the ring on the end of the shifter to the right. Also, many Shimano 7 speed freewheels are index compatible, so you may have an index system without knowing it (the 6400 shifters are 7 speed and the 6401 are 8 speed; it would ironic if you have the 6401!)

rjhammett

Don't you also want the Superbe Pro front wheel/hub for cheap? Anyway, I will be replacing the Campy friction shifters with 600/Ultegra 6400 DT shifters or Dura Ace 7401 DT shifters since they are 7 speed index.

Al1943

I think it makes more economic sense to stay with the 7-speed.

If you want to upgrade the bike because it has special sentimental valuable or if you just want the experience it would make more sense to go to 9-speed, not 8, due to the availability of parts. Your old derailleurs will work with 9-speed. You would need new new rear freehub wheel or rebuild the wheel with a new Shimano 8, 9, speed freehub. Also needed would be new shifters, cassette, chain, and bar tape. This can really add up $.

onespeedbiker

A warning if you go with the Dura Ace shifters, the pre 1997 Dura Ace shifters pulled less cable when shifting, so with a non-Dura Ace derailleur will not move far enough to accurately index. To account for the difference you will need going to have to use an alternate cable routing with the 600 derailleur. From the Sheldon Brown web site https://sheldonbrown.com/dura-ace.html#indexing

fietsbob

freehub body is no narrower if you remove 1 cog,

rjhammett

Thanks for reminding me. I have seen that before but had forgotten about it. I would most likely go with the 600/Ultegra shifters unless I find DA for cheap.

Kimmo

7spd freehub body is narrower than 8/9/10 though.

fietsbob

But that was not, really, the question..


[dyslexic correction]

Cassette freehub body for 8 is HG, I think the 7 is still UG
so cog splines are different.

OP: since new 7 speed freewheels have gotten a HG tooth Profile
now, Id just go that way..
8 'speed' is adding 1 cog on the high end of 7 ,
speed same general spacing.
narrower than std 6 but wider than 9

the 'centron' top pulley float sideways makes up minor misalignment.

gyozadude

I have upgrade component groups, sort of on a 1988 Bianchi Limited and a 1991 Bridgestone RB1. Both with Ultegra 600 Tricolor 6400 series. Both had/have 7spd cassettes. I did cold set both frames (both are steel) to 130mm spacing and added 4mm of spacers on the non-drive side to hit 130mm (I'm a clyde and wanted reduced dish). I was able to retro-fit ACX/Acera freehub body onto the older 6400 freehub and use a 7spd 13-23 and 12-23 HG cassettes. I scrounged around eBay and the like for older 7spd STI brifters. The ST-3300 sora line might still be available. I still have the option to go 8 or 9 speed someday with the right brifters.

But sticking with 7-spd wasn't too expensive. About $80 for the brifters and cables, $25 for the cassette, $18 for the freehub, $5 for a new chain. Shifts and rides just fine.

Back then, I priced a 2 x 8 or 2 x 9 setup, and since my frames are cold set, I have that option. I might pay an extra $20 for the chain and then use up one of my newer hubsets and road rimsets I keep in stock for some strange reason :-). But the cost for older retro 2 x 8 or 2 x 9 brifters is pretty cheap these days and a LOT more available. I think you might do well either way. And if money isn't an object, a 2 x 10 setup with Ultegra components on a retro steel RB-1 sounds kinda cool. Might consider that for the holidays.