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#1
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6 speed shifter...7 speed block.....
Plan to change the rear cogs from a 6-speed sis type to the 7 speed 14-34
megarange type. Obviously I'll need to change the rear mech (old one's past it anyway) but do I really need to change the front shifter? OK so it's not going to 'index' properly but that's of little interest to me so long as I can shift from one end of the set to the other.... Anyone see any problems with me keeping the original shifter? |
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#2
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6 speed shifter...7 speed block.....
LaoFuZhi wrote:
Plan to change the rear cogs from a 6-speed sis type to the 7 speed 14-34 megarange type. Obviously I'll need to change the rear mech (old one's past it anyway) but do I really need to change the front shifter? OK so it's not going to 'index' properly but that's of little interest to me so long as I can shift from one end of the set to the other.... Anyone see any problems with me keeping the original shifter? You will not be able to use a 6 speed shifter with a 7 speed cassette/block in indexed mode. It will constantly rub against adjacent sprockets unless you are very very lucky with the adjustment. You may not need to change the rear mech. but if its past it .... In friction mode you shifter ought to be OK. Why not change the shifter ? |
#3
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6 speed shifter...7 speed block.....
LaoFuZhi wrote:
Plan to change the rear cogs from a 6-speed sis type to the 7 speed 14-34 megarange type. Obviously I'll need to change the rear mech (old one's past it anyway) but do I really need to change the front shifter? OK so it's not going to 'index' properly but that's of little interest to me so long as I can shift from one end of the set to the other.... Anyone see any problems with me keeping the original shifter? Hi, you may find that the 7 speed block won't fit on your 6 speed hub. Also a wheel with a 7/8/9 speed hub won't fit into your frame. This is because the 6 speed hub is slightly narrower. At least, that was my experience when trying to upgrade a six speed bike from 1989. Frames can be stretched through a process known as cold setting so that 7/8/9 speed hubs can be fitted. |
#4
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6 speed shifter...7 speed block.....
Rob Horton yahoo.com@mr_horton opined the following...
LaoFuZhi wrote: Plan to change the rear cogs from a 6-speed sis type to the 7 speed 14-34 megarange type. Obviously I'll need to change the rear mech (old one's past it anyway) but do I really need to change the front shifter? OK so it's not going to 'index' properly but that's of little interest to me so long as I can shift from one end of the set to the other.... Anyone see any problems with me keeping the original shifter? I suspect that a 7 speed shifter may need to pull more cable than a 6 speed. Consult Sheldon. At least, that was my experience when trying to upgrade a six speed bike from 1989. Frames can be stretched through a process known as cold setting so that 7/8/9 speed hubs can be fitted. Cold setting is a steel thing. I don't know that anyone recommends cold- setting Aluminium. Jon |
#5
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6 speed shifter...7 speed block.....
Rob Horton wrote:
you may find that the 7 speed block won't fit on your 6 speed hub. Also a wheel with a 7/8/9 speed hub won't fit into your frame. This is because the 6 speed hub is slightly narrower. At least, that was my experience when trying to upgrade a six speed bike from 1989. Frames can be stretched through a process known as cold setting so that 7/8/9 speed hubs can be fitted. My tourer, frame dating from 1984, got upgraded from 6 to 7 last year. Block fitted OK; I just had to put a washer about 1mm thick on each end of the axle to sprong the frame out a little. -- Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/ ================================================== ========= Editor - British Human Power Club Newsletter http://www.bhpc.org.uk/ ================================================== ========= |
#6
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6 speed shifter...7 speed block.....
Rob Horton wrote:
LaoFuZhi wrote: Plan to change the rear cogs from a 6-speed sis type to the 7 speed 14-34 megarange type. Obviously I'll need to change the rear mech (old one's past it anyway) but do I really need to change the front shifter? OK so it's not going to 'index' properly but that's of little interest to me so long as I can shift from one end of the set to the other.... Anyone see any problems with me keeping the original shifter? Hi, you may find that the 7 speed block won't fit on your 6 speed hub. Also a wheel with a 7/8/9 speed hub won't fit into your frame. This is because the 6 speed hub is slightly narrower. At least, that was my experience when trying to upgrade a six speed bike from 1989. Frames can be stretched through a process known as cold setting so that 7/8/9 speed hubs can be fitted. I think a 7 speed cassette will be OK on a 6 speed hub, you may be right if the OP is using a screw on block though. I have test fitted a 7 speed cassette on my 6 speed hub OK, the wheel fits into the frame perfectly. I actually changed to 8 speed by using 9 speed sprockets and spacers which gives a total width near enough the same as 7 speed. I used a 9 speed chain and 9 speed levers too of course. |
#7
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6 speed shifter...7 speed block.....
On Wed, 21 Jul 2004 08:44:22 +0100, "Martin 'MSeries' Newstead"
wrote: LaoFuZhi wrote: Plan to change the rear cogs from a 6-speed sis type to the 7 speed 14-34 megarange type. Obviously I'll need to change the rear mech (old one's past it anyway) but do I really need to change the front shifter? OK so it's not going to 'index' properly but that's of little interest to me so long as I can shift from one end of the set to the other.... Anyone see any problems with me keeping the original shifter? You will not be able to use a 6 speed shifter with a 7 speed cassette/block in indexed mode. .....except if you're shifter is a Suntour and you're cassette is Shimano. I have an old Schwin road bike in Sacramento that came with Suntour stem mounted shifters and a Suntour 6 gear freewheel. The Suntour shifters pull a different ratio of cable compared to Shimano shifters, slightly less in fact, and this prves to be just dandy for a standard 7 speed shimano freewheel. Works fine. Chances are the shifters are not Suntour though :-) Garry It will constantly rub against adjacent sprockets unless you are very very lucky with the adjustment. You may not need to change the rear mech. but if its past it .... In friction mode you shifter ought to be OK. Why not change the shifter ? |
#8
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6 speed shifter...7 speed block.....
garryb59 wrote:
....except if you're shifter is a Suntour and you're cassette is Shimano. I have an old Schwin road bike in Sacramento that came with Suntour stem mounted shifters and a Suntour 6 gear freewheel. The Suntour shifters pull a different ratio of cable compared to Shimano shifters, slightly less in fact, and this prves to be just dandy for a standard 7 speed shimano freewheel. Works fine. Chances are the shifters are not Suntour though :-) OP said SIS so I presume it was Shimano |
#9
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6 speed shifter...7 speed block.....
Thanks to all for the responses........
I should perhaps have said that the new block was already attached to a replacement wheel which fitted the frame with no problems. Given the apparent likliehood of the shifter not being suitable I may as well order a replacement with the rear mech ...I was merely hoping to make the job a tad simpler (lazy sod that I am g) |
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