Fixed gear conversion questions



On Sun, 09 May 2004 21:01:33 -0400, Michael Press wrote:

> Yes, I'd prefer a lockring even though I'll keep the brake(s). I've
> also discovered since my original post that the bike actually has
> "semi-horizontal" dropouts - much closer to horizontal than vertical,
> so I'm defintely going forward with this.


If there is room to move the wheel forward or backward about 1/2", that
will do nicely. Forget, though, the tensioner. If you only have 1/4" of
forward/rearward motion, you can still make it work. You may not need
this if the numbers work out in your favor, but you can get extra
flexibility by getting a half-link. These are only available for 1/8"
chain, which you can use.

>
> Can you give more detail on this - what's a bottom bracket lockring? Is
> that from an old-style bottom bracket?


Yes. The old, non-cartridge bottom brackets use a separate lockring on
the left side to secure the left cup. On English thread bottom brackets,
that lockring will fit on the hub threads of an old freewheel-style hub.
I do suggest that a real track hub is better, but....

I recall the last BB
I installed
> (a few years ago), a cartridge-type, each half of the BB screwed in on
> opposite sides, but I don't recall a lockring. Can this still be bought
> or do you have to scavenge an old BB?


Should be available, but not easy to find. Easier to find an old bike --
cheaper to buy the bike for the lockring than to order it special. Seems
a waste, but you can put a cartridge bottom bracket on the old bike,
maybe.

>
> Also, does the lockring screw into the hub threads after the cog? If
> not, what do you mean by Locktiting "overtop of the cog"?


If you are not using a track hub, which has left-hand threads for the
lockring, some sort of goop to hold the lockring and sprocket in place is
a good idea.

--

David L. Johnson

__o | What is objectionable, and what is dangerous about extremists is
_`\(,_ | not that they are extreme, but that they are intolerant. --Robert
(_)/ (_) | F. Kennedy
 
Michael Press <[email protected]> wrote in message news:<[email protected]>...
> I'm going to convert my old 7-speed road bike to fixed gear. I want
> to do it as cheaply as possible; if I really enjoy it I'll spend more
> later or get a "real" fixed gear bike.
>

<SNIP>

If you really mean "as cheaply as possible" then you can
1. disassemble the freewheel & degrease the innards
2. reassemble it using JB Weld or similar structural
epoxy instead of lubricant (put the bearings into the
epoxy so that it aligns... experience talking)
3. shuffle cogs, if desired, to improve chainline
4. degrease & threadlock the freewheel onto the hub
5. possibly swap inner and outer chainrings to give more
gear ratios with a smaller chain length variation

Forget that "buying" and redishing for a while.
Maybe buy (Ouch!) SRAM powerlink(s) to trivialize chain
length/gear ratio changes.

Using 39 and 42t rings can give several ratios with no
chain length changes (depends on your dropouts). I've been
happy riding fixed on my 53t ring with only horiz dropouts
supporting changing between two "fixed" gears. I change
gears on the road in about a minute.

I'm suspicious that the use of the larger gears reduces
the tendency to dechain in addition to the increased chain
and gear life you get for free. I did not disturb my
freewheel cogs to optimize chainline nor did I spend on
a new retro-chain.

(on topic) Ed