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Convert 7 Speed to 8-9 speed

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Convert 7 Speed to 8-9 speed

Old 10-10-19, 10:25 AM
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AZ4Mtb
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Convert 7 Speed to 8-9 speed

Rebuild questions for a 1993 Bridgestone MB-3. I am putting new wheels, cassette and chain on my MB-3. I also need to replace the original bottom bracket. The new wheel set is from Quality Wheels with current model Deore hubs. The rear freehub is an 8-10 speed model - Deore FH-T610.

I had originally intended to simply stick with a 7 speed cassette but am also considering an upgrade to 9 speed. I understand that I would need to change out rear derailleur, shifters and go with a narrower chain. My question is regarding the front crank and derailleur. I currently have the original Deore DX crank and front derailleur. Do those need to be changed or will they work with a narrow chain? Thanks in advance.

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Old 10-10-19, 10:44 AM
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Old rear derailleur may work.

https://www.sheldonbrown.com/speeds.html#chainrings - article on compatibility. I have run 7/8 speed SunRace crankset with a 9 speed chain.

Front derailleur will probably work. Yes, the chain is narrower, but anyway it has more degrees of freedom (mounting height and angle) than the rear one. It may be hard to adjust it even with 7 speed chain. Changing front to friction shifter will mitigate these problems in case you decide to stick with the old crankset and FD.
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Old 10-10-19, 02:02 PM
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The existing parts should work fine. I have used 9-speed chains on full 8-speed drivetrains before without issue. You should need to change only the cassette, chain, and shifters initially, and that's probably where I'd start.
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Old 10-10-19, 03:16 PM
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Seems to me that if you have an 8-10 speed freehub, you might as well make full use of it.
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Old 10-10-19, 03:57 PM
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I am running a 10 speed Shimano cassette with original 105, indexed, 6 speed , rear and front derailleurs, and original 6 speed 105 DT shift levers set in friction mode. It shifts great, just took a short while to get the travel distance for the levers. If you are a bit off on a shift, just move the levers a bit in the correct direction. Very easy.
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Old 10-10-19, 05:42 PM
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Went from 7 to 9 when ebaying a pair of rims. Changed chain and shifters.... Rder mostly worked but often phantom shifted in the middle.... Finally reached sanity with a 9 speed derailleur. Still happily using the original front derailleur from 1995....
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Old 10-11-19, 11:29 AM
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Originally Posted by delbiker1 View Post
I am running a 10 speed Shimano cassette with original 105, indexed, 6 speed , rear and front derailleurs, and original 6 speed 105 DT shift levers set in friction mode. It shifts great, just took a short while to get the travel distance for the levers. If you are a bit off on a shift, just move the levers a bit in the correct direction. Very easy.
I've been advocating using friction shifting with 10 speed for years here. It does work great. I have 2 bikes with Campy downtube shifters with 10sp rear, I believe both Shimano, but maybe one has Campy on it at the moment. But it doesn't matter. It wasn't the indexed shifters that made 10sp work so well, it is the ramps on the cogs plus the chain. It takes a light touch on the shifter and it is almost never between gears since they are spaced so closely anyway.
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Old 10-11-19, 12:52 PM
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Originally Posted by zacster View Post
I've been advocating using friction shifting with 10 speed for years here. It does work great. I have 2 bikes with Campy downtube shifters with 10sp rear, I believe both Shimano, but maybe one has Campy on it at the moment. But it doesn't matter. It wasn't the indexed shifters that made 10sp work so well, it is the ramps on the cogs plus the chain. It takes a light touch on the shifter and it is almost never between gears since they are spaced so closely anyway.
Do you find friction shifting to get more difficult (or at least more sensitive) with closer gear spacing? I'll be the first to admit that I'm not a professional friction shifter...but I do find it more difficult with my 9-speed bikes than with 8-speed or below (or even traditional 5- and 6-speed spacing). I have found that the wider the spacing, the more forgiving, and less sensitive, the system seems to be.

I don't think your experience and mine are necessarily mutually exclusive. Perhaps you're more adroit at it than I. Or, are you saying that the closer 10-speed spacing means the chain is almost never skipping around -- that no matter where you have the shifter, you're pretty much always positively in a gear?
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Old 10-11-19, 03:17 PM
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Originally Posted by hokiefyd View Post
Do you find friction shifting to get more difficult (or at least more sensitive) with closer gear spacing? I'll be the first to admit that I'm not a professional friction shifter...but I do find it more difficult with my 9-speed bikes than with 8-speed or below (or even traditional 5- and 6-speed spacing). I have found that the wider the spacing, the more forgiving, and less sensitive, the system seems to be.

I don't think your experience and mine are necessarily mutually exclusive. Perhaps you're more adroit at it than I. Or, are you saying that the closer 10-speed spacing means the chain is almost never skipping around -- that no matter where you have the shifter, you're pretty much always positively in a gear?
No, I find it easier. You learn quickly that it only takes a touch to get to the next gear in either direction. I find with wider spacer you need to jockey it around a lot more to kill the noise. With 10sp you are almost never between gears, and besides, you feel the chain respond immediately to the shift because of the ramps on the cassette. None of that kerchunk. And I can also skip from one gear to the other easily. With Shimano it was one at a time, with Campy I can do multiples, but with friction I can go from largest to smallest in one motion and vice versa.
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Old 10-12-19, 08:19 PM
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Shimano 105 on my original 92 Trek 1400 was indexed for 7 speed, but in friction mode covered a 9 speed cassette well...
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Old 10-13-19, 12:32 AM
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Originally Posted by Digger Goreman View Post
Went from 7 to 9 when ebaying a pair of rims. Changed chain and shifters.... Rder mostly worked but often phantom shifted in the middle.... Finally reached sanity with a 9 speed derailleur. Still happily using the original front derailleur from 1995....
Oddly enough, i had the opposite experience. The RD worked pretty well, although you want to try to get the first couple cogs dialed in perfect or, like you said, the tolerances start stacking and it gets sloppy as you get close to the top.

I never had much luck getting a 7-sp triple FD to work with a 9-sp chain and indexed shifters. You had to push the cage so far to get the chain to pick up the next ring, that you used the whole shift, and the trim positions, that now there wasn't enough throw left in the shifter to make the next one. I imagine this wouldn't be a problem running friction, but i was trying to work with the shifters at hand.
The one double i did, an RX-100 (7/8-sp) had no problems with a 9-sp chain and cranks.
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Old 11-03-19, 07:22 PM
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MB-3 Rebuild Questions - Half Way There

Thanks for all the helpful replies. As posted before, I am rebuilding a Bridgestone MB-3 that needed new wheels and new drive train. I am at the point where I need to figure out my proper bottom bracket spindle length as the BB also needs to be replaced. As per previous I am converting the bike from 3x7 to 3x8 while I am at it. The original component group was all Deore DX. Here is what I have obtained for the upgrade followed by what I have done so far:

New Alex DT19 Rims with Shimano Deore Hubs (8-11 speed non disk rear hub 135mm spacing).
New (old) Deore XT M739 3x8 rapid fire shifters
New (old) Deore XT M739 rear derailleur
New (old) Deore XT M735 front derailleur
New SHIMANO 8 Speed Cassette - HG50 and new HG71 Chain

While the original dropout spacing for the MB-3 is specified as 135mm I had to cold form the rear triangle to fit the new rear hub because it was about 2.5mm too tight. I could get the rear wheel in but I required me to muscle it somewhat. Now it pops into place with minimal effort and will fall out of the dropouts if the QR is opened.

The rear cassette is installed and the wheels are on and I have measured for chain line with the new hub/cassette combo. I am keeping the original Deore DX crank and just installing new chain wheels. My new rear chain line is 43.5mm and my front chain line is 47mm with the DX crank and the original Tioga BB40. The Tioga BB has a 120mm spindle and I want to replace it with a sealed cartridge setup. I am looking at the Origin8 Torqlite or the OMNI Racer JIS Square Taper BBs. Sheldon Brown's guide to BBs shows the symmetrical equivalent for a 120mm spindle as 124mm. If I am understanding all of this correctly, I've moved the chain line of my rear cassette in about 2-3mm closer to the center line of the bike with the jump from a 7 speed to an 8 speed rear hub. So, can I install BB with a 122.5 spindle and end up with a 45.5 front CL? That would leave me with a 2mm difference back to front if I am understanding the effect of spindle length on the chain line. Also, nobody seems to make a 124mm spindle anyway so I would need to go up to 127mm and that seems like the wrong direction to be headed...

Thanks again.
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Old 11-03-19, 09:31 PM
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Originally Posted by AZ4Mtb View Post
Thanks for all the helpful replies. As posted before, I am rebuilding a Bridgestone MB-3 that needed new wheels and new drive train. I am at the point where I need to figure out my proper bottom bracket spindle length as the BB also needs to be replaced. As per previous I am converting the bike from 3x7 to 3x8 while I am at it. The original component group was all Deore DX. Here is what I have obtained for the upgrade followed by what I have done so far:

New Alex DT19 Rims with Shimano Deore Hubs (8-11 speed non disk rear hub 135mm spacing).
New (old) Deore XT M739 3x8 rapid fire shifters
New (old) Deore XT M739 rear derailleur
New (old) Deore XT M735 front derailleur
New SHIMANO 8 Speed Cassette - HG50 and new HG71 Chain

While the original dropout spacing for the MB-3 is specified as 135mm I had to cold form the rear triangle to fit the new rear hub because it was about 2.5mm too tight. I could get the rear wheel in but I required me to muscle it somewhat. Now it pops into place with minimal effort and will fall out of the dropouts if the QR is opened.

The rear cassette is installed and the wheels are on and I have measured for chain line with the new hub/cassette combo. I am keeping the original Deore DX crank and just installing new chain wheels. My new rear chain line is 43.5mm and my front chain line is 47mm with the DX crank and the original Tioga BB40. The Tioga BB has a 120mm spindle and I want to replace it with a sealed cartridge setup. I am looking at the Origin8 Torqlite or the OMNI Racer JIS Square Taper BBs. Sheldon Brown's guide to BBs shows the symmetrical equivalent for a 120mm spindle as 124mm. If I am understanding all of this correctly, I've moved the chain line of my rear cassette in about 2-3mm closer to the center line of the bike with the jump from a 7 speed to an 8 speed rear hub. So, can I install BB with a 122.5 spindle and end up with a 45.5 front CL? That would leave me with a 2mm difference back to front if I am understanding the effect of spindle length on the chain line. Also, nobody seems to make a 124mm spindle anyway so I would need to go up to 127mm and that seems like the wrong direction to be headed...

Thanks again.
Hey, if you want to part with your old DX rear shifter, I could use it. I just rebuilt my 1990 Trek 8000 with DX, a very light rebuild, but shifting was a problem. When I opened up the shifter to change the cable, I somehow managed to pop the return spring and in reassembly seem to have bent it to where it no longer has any springyness to it. Anyway, I'm really just looking for the spring. The rest of the rebuild just included new fat tires to go back closer to original, and a new chain. Everything else is still intact. It just bothers me that I somehow killed that spring. In the meantime, I just need to push back on the downshifter (to a larger rear cog) when I use it and it all otherwise works.
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Old 11-03-19, 10:05 PM
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Originally Posted by AZ4Mtb View Post
I understand that I would need to change out rear derailleur, shifters and go with a narrower chain. My question is regarding the front crank and derailleur. I currently have the original Deore DX crank and front derailleur. Do those need to be changed or will they work with a narrow chain? Thanks in advance.
I don't know enough to add to the answers you've received. However, for the RD you could open up the rear wheel spacing and use normal 8-9 speed cassette. The MB-3 is a chromoly frame, yes?
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Old 11-03-19, 10:11 PM
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Originally Posted by WizardOfBoz View Post
I don't know enough to add to the answers you've received. However, for the RD you could open up the rear wheel spacing and use normal 8-9 speed cassette. The MB-3 is a chromoly frame, yes?
Thanks for your reply. I am way past this part. I have already opened up my rear spacing and have wheels installed. I am trying to figure out chain line. I think I need to start a new thread because I am getting lots of responses to the older parts of this one...
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Old 11-05-19, 07:48 AM
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I'm messing with several 90's 3X7 mountain bikes. Still original Deore setups. They came with a 122.5 BB. 135mm rear spacing. I think the 122.5 is too long. That's just from eyeballing the chain line angles by eye. I changed one bike to a 118mm BB. I think that centers the chain better on the rear cogs. I'm looking at moving to 3X8. For me a 120mm BB would be what I'd like using with that setup.
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