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Discussion Starter · #1 ·
At first this seem strange but I want to reduce the # of speeds on my dh bike. The bike in question is a 2004 giant dh, which with it's 100mm bottom bracket shell with a 135 mm hub makes for a very bad chain line in the lower gears. The lowest 3 gears are almost unusable but for slowspeed stuff sometimes they are usefull. I want to reduce the number of speeds to 6 so I can space the cassett away from the hub and space the remaining gears to a usable position and better chainline. I have a lx cassett that i can strip down for the cogs, I'm thinking of ditching the middle 3 gears. Has anyone done this, I used the search but no luck.
 

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Sure you can do it and it is a great idea. The easiest way to to just move the 3 cogs and spacers you do not want to use to the inside of the largest cog on the freehub body. Readjust your derailleur low limit screw so you can not shift to the inner-most cogs.

If you still want your largest cog I would remove something like the 3rd, 5th and 8th cogs (from the outside) from the LX cassette
 

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Master of None
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How's your project going? I have something similar going on, from 9 to 5 speed. I have the rear cogs all installed, seems to shift ok. I just need some more parts to finish it off.
 

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Discussion Starter · #5 ·
I performed the changeover to 6 speeds and all went well ,the bike shifts fine because I kept the cog spacing the same as normal. People look at me strange, but I'm used to that ;) I'll post pics latter.
 

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The major advantage to going to 6-speed is to keep the chainline more straight (so it's not going to extreme angles at either gear-spread end).

If your really want to do it right, try out PVD's info:

http://www.pvdwiki.com/index.php?title=Six_Speed_MTB

I'm happy with my 1x9, but of I made the jump to a 6-speed, PVD's got the right idea there.

Cheers, Chris
 

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Master of None
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I set up the cassette as 32, 24,18,14,12. My chainring is a 38. I noticed that it is not as crisp shifting because the tooth difference from cog to cog is greater... My bottom bracket is wrong so my chainline is off, and I have ordered a short cage derailleur. I think with a little more tweaking it will be good.
 

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presslab said:
I set up the cassette as 32, 24,18,14,12. My chainring is a 38. I noticed that it is not as crisp shifting because the tooth difference from cog to cog is greater... My bottom bracket is wrong so my chainline is off, and I have ordered a short cage derailleur. I think with a little more tweaking it will be good.
I have one of my bikes setup as a 1x5:
  • Cheap (Nashbar?) 8sp 12-32 cassette keeping the 2 smallest cogs, removed every-other cog then added a 1mm spacer between each cog in addition to the regular spacer.
  • Spacers to fit behind the cog stack
  • XT medium cage RD (8/9sp)
  • 9sp SRAM chain
  • Old SunTour 6sp barend shifter
Crank chainline adjusted to match the cogs.
Shifts perfectly and instantly even though the cogs' ramps do not line up "properly."
The wider cogs spacing is less affected by muck and debris, and the indexing stays in adjustment better. No issues with the narrow chain falling between the cogs, always drops onto the teeth.
 

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a 1x5 is what i'd like to build. does anyone have pictures?

the sample in pvdwiki uses a 970 cassette. what are my options for other cassettes that can be similarly disassembled? i'm looking to convert from an 8 speed.

thanks.
 

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newaccount said:
a 1x5 is what i'd like to build. does anyone have pictures?

the sample in pvdwiki uses a 970 cassette. what are my options for other cassettes that can be similarly disassembled? i'm looking to convert from an 8 speed.

thanks.
You can break apart any cassette that does not have a carrier spider for the larger cogs. Basically any of the cheaper models.
 

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thanks for the info.

i guess especially with the cheaper and heavier models, i'd want to limit myself to 4-5 gears.

it seems like the sram cassette shown can be put back together with the hex screw. i believe shimanos are riveted(?) being able to pack it back together instead of having individual cogs hanging loose is a concern for me b/c i don't want the big cogs biting into my spline. how would you deal with a 5-pack cassette if you're using the set screws?
 

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newaccount said:
thanks for the info.

i guess especially with the cheaper and heavier models, i'd want to limit myself to 4-5 gears.

it seems like the sram cassette shown can be put back together with the hex screw. i believe shimanos are riveted(?) being able to pack it back together instead of having individual cogs hanging loose is a concern for me b/c i don't want the big cogs biting into my spline. how would you deal with a 5-pack cassette if you're using the set screws?
If your freehub body is steel it does not matter. Run the stack of loose cogs.

If you setup the cassette as I suggested to the OP you can just bolt the stack back together.
 

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shiggy said:
I have one of my bikes setup as a 1x5:
  • Cheap (Nashbar?) 8sp 12-32 cassette keeping the 2 smallest cogs, removed every-other cog then added a 1mm spacer between each cog in addition to the regular spacer.
What prompted you to add a 1mm spacer? Did this improve shifting performance?

Right now it hesitates going from the 24 to the 32. Maybe this is too big a jump? I'm hoping the short cage derailleur might improve this.

I am running the loose cogs with some spacers from another junk cassette so I only have the cogs I want on there. The 12t was a little tricky as the spacers were too large in diameter. However, I found a spacer from a SRAM cassette that was smaller and allowed the chain to drop down into the teeth properly.
 

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I'm guessing that the 1mm spacer worked better with your SunTour shifter? This is an indexed shifter it seems.

I guess I never have problems with the cassette getting packed with mud. Just trying to understand if you added the 1mm spacer to solve a particular problem you were having.
 

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presslab said:
I'm guessing that the 1mm spacer worked better with your SunTour shifter? This is an indexed shifter it seems.

I guess I never have problems with the cassette getting packed with mud. Just trying to understand if you added the 1mm spacer to solve a particular problem you were having.
I set this up with a friction shifter at first. That the indexed 6sp shifter works was a happy accident.

If you have never used wide(r) spaced 5, 6, 7-sp cogs you have no idea how much less fussy they are to maintain and operate. I would still use un-ramped cogs if I could, too.
 

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shiggy said:
If you have never used wide(r) spaced 5, 6, 7-sp cogs you have no idea how much less fussy they are to maintain and operate. I would still use un-ramped cogs if I could, too.
I have a set of 1993 Deore/Mavic wheels with 7 speed Shimano freewheel that have less than 200 miles on them. I bought some 6 speed XT thumb shifters off eBay that have a 7th ghost shift. I want to build a 1X7 but am concerned about chainline in the big and small cog being too far in distance for the chain. Would 1X6 be a better idea? What do you think?
 

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shiggy- one more question and i think i can start ripping my cassette apart.

how do rear shifters/derailleurs work? this is kinda hard to explain in words but i'll try. on the rear derailleur, there are hi/low set screws. if i want to make 5 speeds, do i just limit the travel to speeds 3 to 7? i am assuming indexing works by pulling the cable the same exact length with each click. will the set screws reach to provide these limits?

as an alternative, i was also thinking along the lines of the old thumb shifters. i can use any old one regardless of how many speeds and take it off of indexing and using the friction mode.

thanks.
 

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thebreeze said:
I have a set of 1993 Deore/Mavic wheels with 7 speed Shimano freewheel that have less than 200 miles on them. I bought some 6 speed XT thumb shifters off eBay that have a 7th ghost shift. I want to build a 1X7 but am concerned about chainline in the big and small cog being too far in distance for the chain. Would 1X6 be a better idea? What do you think?
Even if you do not change the chainline of the crank the overall chainline will be BETTER with the 7-sp FW than an 8/9-sp cassette. It is the same chain angle for the smaller cogs and much better for the largest.
 

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newaccount said:
shiggy- one more question and i think i can start ripping my cassette apart.

how do rear shifters/derailleurs work? this is kinda hard to explain in words but i'll try. on the rear derailleur, there are hi/low set screws. if i want to make 5 speeds, do i just limit the travel to speeds 3 to 7? i am assuming indexing works by pulling the cable the same exact length with each click. will the set screws reach to provide these limits?

as an alternative, i was also thinking along the lines of the old thumb shifters. i can use any old one regardless of how many speeds and take it off of indexing and using the friction mode.

thanks.
*sigh*

I am going to let some one else explain this
 
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