>
> 3) Anything I didn't think of?
> A: What's wrong with shifting?
>
> Nothing. It just drives me nuts commuting because I always seem to need
to be in the 5 gears that lie across the 53/39 split. That and it seemed
inticing to get rid of one more thing that needs maintenance (the front
derailleur).
-Joel
----- Original Message -----
From: Joel Morrissette
To: obra@list.obra.org
Sent: Friday, September 22, 2006 1:31 PM
Subject: [OBRA Chat] Single chainring setup
For my commuter bike I'm thinking of going to a single chainring setup because I'm incessantly shifting between chainrings on my ride. I currently run a 53/39 with a 12-26 cassette on 175 cranks. Here are my questions:
1) According to Sheldon Brown's calculator, I can go to a 42 or 44 tooth ring and the upper end will functionally be like a 53/14, and the bottom end at 39/23, which is workable. Will a 42 or 44 fit on the inner position and still clear the chainstay? I'm riding a Lemond Poprad.
A: Probably
1b) If not, what can I do? I suppose running on the outside might work. Is there a lateral adjustment on a 105 octalink bottom bracket?
A: If it's a small adjustment, you can put a 1 or 1.5mm freewheel spacer under the drive side or you can get a longer BB axle.
2) I was told once that the reason you don't cross-gear is that it increases your chain wear and breakage. Running a single ring means I would definitely be running a combination that is cross-gearing. Should I worry?
A: No.
Is this hard on the chain or derailleur?
A: It's hard on the chainring and chain.
3) Anything I didn't think of?
A: What's wrong with shifting?
-Joel
--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond
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Lots of great responses. Here's the answers:
1) According to Sheldon Brown's calculator, I can go to a 42 or 44 tooth
> ring and the upper end will functionally be like a 53/14, and the bottom end
> at 39/23, which is workable. Will a 42 or 44 fit on the inner position and
> still clear the chainstay? I'm riding a Lemond Poprad.
Probably, but close. With an Octalink bracket, it's likely not an issue due
to stiffness.
1b) If not, what can I do? I suppose running on the outside might work.
> Is there a lateral adjustment on a 105 octalink bottom bracket?
One respondant reports having a better chainline outside. Pick whichever
works for the better chainline up the middle. One advocates for a square
taper setup just for this kind of adjustment. Another suggested an Octalink
track crank for best results.
2) I was told once that the reason you don't cross-gear is that it
> increases your chain wear and breakage. Running a single ring means I would
> definitely be running a combination that is cross-gearing. Should I worry?
> Is this hard on the chain or derailleur?
No and barely. The rear derailleur should be fine, and the chain needs
replacing anyway. Modern chains are build for a fair amount of abuse, so
this is unlikely to cause any additional pain.
3) Anything I didn't think of?
My big ring is too big for the riding I'm doing, and I should put on a 48 or
50. This completely makes sense now that I look at it. A 48t gives me all
the ratios I need for my commute, plus the bottom end I need for climbing on
the 39.
So....
Anyone out there have a 48t, 130BCD black FSA chainring they'd sell or trade
for a practically new 53t of same make? Thought I'd check before
ordering...
Thanks for all the info.
-Joel
1. yes a 42 or 44 should fit and not hit the chainstay... a 44 might be close though.. sometimes you can flip the chainring too, if it is not symmetric.. and you can use little shims to laterally adjust the bb, of course then you will be off center of frame a little. But sometimes all you need is a .5mm for chainring clearance and thats not much off center. [this is one of the reasons I am still using square taper.. a lot of options to get you exactly the spacing you want or need.] but octalink is stiffer though so it won't tend to flex over and hit the chainstay, so you are able to initially set up a little closer. You could also possibly get octalink track crank... the chainring should be in the middle of the two on a double..?
2. crossgearing: Well it depends where things line up. I use to like a lot of closely spaced cogs in the back, and thus reason for 9 speed then 10 speed. you get that just slighter bigger or smaller gear.. but after riding around on a single speed, i now tend to like fewer gears and bigger jumps in between the gears.. So i usually run with a 7 speed freehub (with 9 speed spacers/cogs). Obviously not as wide so you don't have to worry as much about cross gearing in either small or large cogs..
But anyway, i wouldn't worry about it too much. Just try to line up the chainring with the middle of the cogs, or where you tend to run most of the time and then just ride . chains are made to handle this, and you slap new ones on occasionally anyway..
3. I might leave the front derailluer on there anyway .. or some sort of guide. For some reason the chain seems to like to jump off when running just a single up front..
Joel Morrissette wrote:
For my commuter bike I'm thinking of going to a single chainring setup because I'm incessantly shifting between chainrings on my ride. I currently run a 53/39 with a 12-26 cassette on 175 cranks. Here are my questions:
1) According to Sheldon Brown's calculator, I can go to a 42 or 44 tooth ring and the upper end will functionally be like a 53/14, and the bottom end at 39/23, which is workable. Will a 42 or 44 fit on the inner position and still clear the chainstay? I'm riding a Lemond Poprad.
1b) If not, what can I do? I suppose running on the outside might work. Is there a lateral adjustment on a 105 octalink bottom bracket?
2) I was told once that the reason you don't cross-gear is that it increases your chain wear and breakage. Running a single ring means I would definitely be running a combination that is cross-gearing. Should I worry? Is this hard on the chain or derailleur?
3) Anything I didn't think of?
-Joel
--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond _______________________________________________
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obra@list.obra.org
http://list.obra.org/mailman/listinfo/obra
Unsubscribe: obra-unsubscribe@list.obra.org
For my commuter bike I'm thinking of going to a single chainring setup
because I'm incessantly shifting between chainrings on my ride. I currently
run a 53/39 with a 12-26 cassette on 175 cranks. Here are my questions:
1) According to Sheldon Brown's calculator, I can go to a 42 or 44 tooth
ring and the upper end will functionally be like a 53/14, and the bottom end
at 39/23, which is workable. Will a 42 or 44 fit on the inner position and
still clear the chainstay? I'm riding a Lemond Poprad.
1b) If not, what can I do? I suppose running on the outside might work.
Is there a lateral adjustment on a 105 octalink bottom bracket?
2) I was told once that the reason you don't cross-gear is that it
increases your chain wear and breakage. Running a single ring means I would
definitely be running a combination that is cross-gearing. Should I worry?
Is this hard on the chain or derailleur?
3) Anything I didn't think of?
-Joel
--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond
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