Convert 6spd shimano 600 to 7 spd?
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Convert 6spd shimano 600 to 7 spd?
My bike is a 1986 Centurion Dave Scott Ironman with 600ex 6spd 13-21 cluster. My 60 yr old legs cannot get up some of the climbs anymore with nothing lower than 42/21. I have read in a couple places including Sheldon Brown that I should be able to switch to a 7 speed freewheel (thinking 14-28), new chain and index shifting will still work? Just making sure before I order parts. Any and all ideas are appreciated!
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A 28T cog is too much for most short cage derailleurs, which is why I use a hard-to-find 26T low on most of my road bikes. Coupled with a 42T inner chainring, this is much better than fighting a 42/21, or even a 42/23, up a steep hill. Although the Bianchi came with 52-42/13-15-17-19-21-23, I changed it to 50-42/14-16-18-20-23-26, which is still a 12-speed configuration. I have also used a 13-15-17-19-21-23-26 7-speed freewheel on a different rear hub.
See other recent threads regarding the relative OLD requirements of 6-speed and 7-speed freewheels. Usually, a 1 or 2mm spacer on the right side is all that's needed to make the smallest cog usable.
See other recent threads regarding the relative OLD requirements of 6-speed and 7-speed freewheels. Usually, a 1 or 2mm spacer on the right side is all that's needed to make the smallest cog usable.
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Thanks John. I thought that might be the case. I will keep looking for a freewheel with a 25 or 26T low. I mention the 25T because I did see one on ebay. I'll also check w/ one of my LBS who I know happens to have quite a bit of "stuff" in the back. Maybe I'll get lucky and he'll have some cogs he can just replace on my current freewheel. If anyone knows of any 7 spd freewheels out there with a 25 or 26 low, I'd love to hear it!
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To be honest, I think you'd need to go lower (bigger) than 25t to make a big change (52.5" to 44" development on lowest gear). If you can swap in a 39t small chainring at the same time, that should be a help (52.5" to 41" development).
Last edited by CO_Hoya; 06-17-14 at 04:15 PM. Reason: Math is hard
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There are some pretty reasonable climbs in Wisconsin and your knees aren't getting any younger. I'd get your idea of a 14-28 freewheel is a good one. I'd get a modern shimano rear derailleur as well; it will handle the freewheel and index. You can pick up a shimano 105 RD for aroound $50; you can pick up a Tiagra if you prefer for less.
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600EX RD will work with a 28t low cog. Therefore, installing an alpine 14-28t 7 speed freewheel will be the quickest and cheapest route. I recommend a new chain like a KMC X.8.
If more clearance is required on the drive side, adding a 1mm washer under the locknut usually is all it takes.
But if you want indexing:
You'll need additional hardware.
1. a Shimano SIS spec rear derailleur.
2. 7-speed DT indexed shifters, or 7-speed brifters.
For a better low range, I also recommend replacing the 42t inner ring with a 39t ring. The crank should be 130mm BCD. Try a local bike co-op for parts. I find chainrings for $5 each. Look for indexing derailleurs and shifters while there.
If more clearance is required on the drive side, adding a 1mm washer under the locknut usually is all it takes.
But if you want indexing:
You'll need additional hardware.
1. a Shimano SIS spec rear derailleur.
2. 7-speed DT indexed shifters, or 7-speed brifters.
For a better low range, I also recommend replacing the 42t inner ring with a 39t ring. The crank should be 130mm BCD. Try a local bike co-op for parts. I find chainrings for $5 each. Look for indexing derailleurs and shifters while there.
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I thought the Ironman had a cassette (that era would be an uniglide version, totally obsolete).
So it starts with verifying whether you currently have a cassette or a freewheel, and if a cassette, whether it is hyperglide or uniglide.
https://sheldonbrown.com/k7.html#hyperdrivec
So it starts with verifying whether you currently have a cassette or a freewheel, and if a cassette, whether it is hyperglide or uniglide.
https://sheldonbrown.com/k7.html#hyperdrivec
Last edited by wrk101; 06-17-14 at 08:15 PM.
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I have that same RD with a 28 tooth 7 speed freewheel on my 1988 Centurion. The placement forward and back of the rear wheel is critical.
Ed
Ed
#9
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I thought the Ironman had a cassette (that era would be an uniglide version, totally obsolete).
So it starts with verifying whether you currently have a cassette or a freewheel, and if a cassette, whether it is hyperglide or uniglide.
Shimano Cassettes & Freehubs
So it starts with verifying whether you currently have a cassette or a freewheel, and if a cassette, whether it is hyperglide or uniglide.
Shimano Cassettes & Freehubs
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Nobody answered the question about indexing yet, so I'll take it. Six speed shifters won't index seven speed gear clusters. If you have a freewheel on there, you can easily replace it with a new 6 speed freewheel with a lower gear (28T). If the bike has a rd-1050 rear derailleur, it'll handle it.
What is the reasoning behind wanting to go to 7 speed? Changing to 7 speeds will get you 1 extra middle gear from a 6 speed cluster that has the same range. A 14-28T freewheel whether it's 6 or 7 speeds will give you the same high and low gears. I can see if you find the difference too great between gears on a 6 speed, or you cannot find the exact tooth counts you want in 6 speed. If those aren't concerns, stick with 6 speed. If you have a UG cassette, all hope is not lost, but you've got to be creative to find reasonable cost replacements.
I think a 39T small chainring in conjunction with the new cluster would make those hills more manageable.
What is the reasoning behind wanting to go to 7 speed? Changing to 7 speeds will get you 1 extra middle gear from a 6 speed cluster that has the same range. A 14-28T freewheel whether it's 6 or 7 speeds will give you the same high and low gears. I can see if you find the difference too great between gears on a 6 speed, or you cannot find the exact tooth counts you want in 6 speed. If those aren't concerns, stick with 6 speed. If you have a UG cassette, all hope is not lost, but you've got to be creative to find reasonable cost replacements.
I think a 39T small chainring in conjunction with the new cluster would make those hills more manageable.
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Nobody answered the question about indexing yet, so I'll take it. Six speed shifters won't index seven speed gear clusters. If you have a freewheel on there, you can easily replace it with a new 6 speed freewheel with a lower gear (28T). If the bike has a rd-1050 rear derailleur, it'll handle it.
What is the reasoning behind wanting to go to 7 speed? Changing to 7 speeds will get you 1 extra middle gear from a 6 speed cluster that has the same range. A 14-28T freewheel whether it's 6 or 7 speeds will give you the same high and low gears. I can see if you find the difference too great between gears on a 6 speed, or you cannot find the exact tooth counts you want in 6 speed. If those aren't concerns, stick with 6 speed. If you have a UG cassette, all hope is not lost, but you've got to be creative to find reasonable cost replacements.
I think a 39T small chainring in conjunction with the new cluster would make those hills more manageable.
What is the reasoning behind wanting to go to 7 speed? Changing to 7 speeds will get you 1 extra middle gear from a 6 speed cluster that has the same range. A 14-28T freewheel whether it's 6 or 7 speeds will give you the same high and low gears. I can see if you find the difference too great between gears on a 6 speed, or you cannot find the exact tooth counts you want in 6 speed. If those aren't concerns, stick with 6 speed. If you have a UG cassette, all hope is not lost, but you've got to be creative to find reasonable cost replacements.
I think a 39T small chainring in conjunction with the new cluster would make those hills more manageable.
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My bike is a 1986 Centurion Dave Scott Ironman with 600ex 6spd 13-21 cluster. My 60 yr old legs cannot get up some of the climbs anymore with nothing lower than 42/21. I have read in a couple places including Sheldon Brown that I should be able to switch to a 7 speed freewheel (thinking 14-28), new chain and index shifting will still work? Just making sure before I order parts. Any and all ideas are appreciated!
Here it shows the sis version and it says 26 tooth but they will do 28 easily VeloBase.com - Component: Shimano RD-6208, 600EX (SIS)
EddyR
Last edited by EddyR; 06-18-14 at 05:12 AM.
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You could convert your bike to a modern gearing system with a new 130 mm rear wheel, a 10 speed cassette, 10 speed downtube shifters or brifters, a new rear derailleur, and a compact crank.
This won't be cheap but you will end up with a lot of really usable gears that will get you up all sorts of hills and mountains too for that matter.
I like my old bikes but that's what I would do for a bike that I rode on a regular basis. You'll get more usable gear ratios this way while significantly improving your climbing gears.
This won't be cheap but you will end up with a lot of really usable gears that will get you up all sorts of hills and mountains too for that matter.
I like my old bikes but that's what I would do for a bike that I rode on a regular basis. You'll get more usable gear ratios this way while significantly improving your climbing gears.
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You could convert your bike to a modern gearing system with a new 130 mm rear wheel, a 10 speed cassette, 10 speed downtube shifters or brifters, a new rear derailleur, and a compact crank.
This won't be cheap but you will end up with a lot of really usable gears that will get you up all sorts of hills and mountains too for that matter.
I like my old bikes but that's what I would do for a bike that I rode on a regular basis. You'll get more usable gear ratios this way while significantly improving your climbing gears.
This won't be cheap but you will end up with a lot of really usable gears that will get you up all sorts of hills and mountains too for that matter.
I like my old bikes but that's what I would do for a bike that I rode on a regular basis. You'll get more usable gear ratios this way while significantly improving your climbing gears.
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If you're only looking to get a lower gear- why not replace the freewheel/cassette for a 14-28 and stay 6 speed. The indexing stays the same- the RD may work.
I really only care about the range- having the steps between makes a difference when racing and to some extent, comfort. I've found I'm perfectly comfortable with a 6 speed- and actually just started using 3x5 bikes- I don't notice a whole lot of difference.
I really only care about the range- having the steps between makes a difference when racing and to some extent, comfort. I've found I'm perfectly comfortable with a 6 speed- and actually just started using 3x5 bikes- I don't notice a whole lot of difference.
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If that is a 1050 RD it will work with a 28T cog and a triple. You just have to experiment with chain length to make sure the RD pulley is not riding the biggest cog. I have this setup on an 87 Ironman. 52/42/30 FC-1057 and 12-28 7speed in back on hard climbing days. Normal is a 13-23 in back. Shimano L-600 barcons handle the shifting since I like friction. About as good as it gets for a friction setup.
The triple in front is the best option in my opinion. You can change out the cassette if you desire, but a new spindle and crankset will get you 6 more gears and a lower end. You can find both on the cheap. Some of the others members can recommend a good crank to put on. I've bought 2 FC-1057. One was NIB and the other slightly used. I spent less that $100 for both and the 2 spindles. Triple FDs are cheap. So are used long cage RDs. Why more people don't go this route baffles me.
The triple in front is the best option in my opinion. You can change out the cassette if you desire, but a new spindle and crankset will get you 6 more gears and a lower end. You can find both on the cheap. Some of the others members can recommend a good crank to put on. I've bought 2 FC-1057. One was NIB and the other slightly used. I spent less that $100 for both and the 2 spindles. Triple FDs are cheap. So are used long cage RDs. Why more people don't go this route baffles me.
Last edited by seypat; 06-18-14 at 06:50 AM.
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You are all awesome! This is my RD: 6208, 600EX (SIS). Since there are tons of 6spd 14-28 freewheels for not much money, that and a new chain are a great start for me. My low gear will be 39.7 instead of 52.9. I'll keep an eye out for a 39 chainring as well. This goes with my idea of keeping the investment real low. Part of me wants to buy a new bike in the next year or so. Main use is training and competing in Triathlons. So I might want a dedicated aero bike. Or I might want a newer, smoother riding road bike I can also use for Tris.
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When I posted, I got the impression you had friction 600EX, if that is not the case and you have 6 speed indexing DT shifters, it's best to get a 6 speed freewheel.
If you actually have a Uniglide freehub system, that becomes more complicated since these cassettes are obsolete. But a little grinding or filing of a HG cog will allow it to fit.
Then you can install your 28t low cog.
If you actually have a Uniglide freehub system, that becomes more complicated since these cassettes are obsolete. But a little grinding or filing of a HG cog will allow it to fit.
Then you can install your 28t low cog.
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