Dumb de-railer refitting question

"Stuart Millington" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

My bike, is a £100 cheapo from Decathlon (as I may have mentioned
before, sorry). But, I really haven't got the hang of the 21-speed
de-railer(!) gears - I sort of stall whenever changing down whilst
going up a hill - and would prefer something more like an old 7 speed
cassette hub.

Is it worth talking to the LBS about re-fitting this thing or would it
cost more than a basic bike with a single front cog and a cassette in
the rear?

You've already got a basic bike with a single front cog and a 7-speed
cassette in the rear. It just happens to have the option of a couple of
extra front cogs.

All you need to do to replicate the basic 7-speed thing you're looking for
is to not use the front shifter.

Initially it would probably be worth just not using it - but longer term you
could remove some of the unused bits.

Or when you say cassette hub, do you actually mean hub gear? In which case,
mmm. If you've got horizontal dropouts (see sheldon), it should be possible.
But it'll cost you more than your bike did.

cheers,
clive

in message <[email hidden]>, Stuart Millington

(') said:

My bike, is a £100 cheapo from Decathlon (as I may have mentioned
before, sorry). But, I really haven't got the hang of the 21-speed
de-railer(!) gears - I sort of stall whenever changing down whilst
going up a hill - and would prefer something more like an old 7 speed
cassette hub.

Is it worth talking to the LBS about re-fitting this thing or would it
cost more than a basic bike with a single front cog and a cassette in
the rear?

Let's just get out terminology straight.

A derailleur is a mechanism for moving a chain from one sprocket to
another. A cassette is a pyramid of sprockets which fits onto a freehub,
and is used with a derailleur. Before cassettes there were 'freewheels',
which looked superficially similar except that the ratchet mechanism was
part of the pyramid of sprockets and not part of the hub.

Entirely separate from this line of development is the epicyclic or hub
gear, in which a single front chainwheel drives a single rear sprocket,
which in turn drives a train of sun-and-planet gears inside the body of
the hub body.

OK, having said that, you can simplify gearing on a derailleur bike by
removing or locking the front derailleur and just using the back; or you
can simplify it by replacing the back wheel with one containing an
epicyclic hub.

Derailleurs have a very small efficiency advantage over epicyclics, which
is why they're the preferred gearing system for racers; but this really is
very small. Epicyclics have a significant maintenance advantage over
derailleurs - most of the mechanism is enclosed inside the hub away from
dirt, grit and weather. The very badly made Sturmey Archer epicyclics of
thirty years ago have tended to give epicyclics generally a bad name, but
modern ones are better.

The other significant difference between the two systems is in use. On a
(good) derailleur system you can change gear under full power (although
it's kinder not to), but you can't change gear at standstill. Again, this
suits racers. With an epicyclic it's usually not a good idea to change
gear under full power, but you can change gear when freewheeling or at
standstill.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

-- mens vacua in medio vacuo --

Simon Brooke said:

With an epicyclic it's usually not a good idea to change
gear under full power, but you can change gear when freewheeling or at
standstill.

IIRC, with the old Sturmy Archer (shudder) changing down under power was like
having a pre-selector. It would change as soon as you eased off the pedalling.

I don't think I ever tried to pull the lever hard enough to change up under
power.

In article <[email hidden]>, Stuart
Millington
[email hidden] says...

Quoted message said:

My bike, is a £100 cheapo from Decathlon (as I may have mentioned
before, sorry). But, I really haven't got the hang of the 21-speed
de-railer(!) gears - I sort of stall whenever changing down whilst
going up a hill

Change down earlier - if you wait until you're pedalling slow and hard
then cheap gears don't shift easily.

(Ziggy) said:

Simon Brooke said:

With an epicyclic it's usually not a good idea to change
gear under full power, but you can change gear when freewheeling or at
standstill.

IIRC, with the old Sturmy Archer (shudder) changing down under power was like
having a pre-selector. It would change as soon as you eased off the pedalling.

I don't think I ever tried to pull the lever hard enough to change up under
power.

Reverse the above!

It's changing up where it acts like a pre-selector.

As soon as I got on a bike, I remembered.

Clive George said:

"Stuart Millington" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

My bike, is a £100 cheapo from Decathlon (as I may have mentioned
before, sorry). But, I really haven't got the hang of the 21-speed
de-railer(!) gears - I sort of stall whenever changing down whilst
going up a hill - and would prefer something more like an old 7 speed
cassette hub.

Is it worth talking to the LBS about re-fitting this thing or would it
cost more than a basic bike with a single front cog and a cassette in
the rear?

You've already got a basic bike with a single front cog and a 7-speed
cassette in the rear. It just happens to have the option of a couple of
extra front cogs.

All you need to do to replicate the basic 7-speed thing you're looking for
is to not use the front shifter.

True, but a single ring bike would probably have wider spacing on the back,
so it might still make sense to change the cassette to a Shimano Megarange
or something.

Jim Higson said:

Clive George said:

"Stuart Millington" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

My bike, is a £100 cheapo from Decathlon (as I may have mentioned
before, sorry). But, I really haven't got the hang of the 21-speed
de-railer(!) gears - I sort of stall whenever changing down whilst
going up a hill - and would prefer something more like an old 7
speed cassette hub.

Is it worth talking to the LBS about re-fitting this thing or would
it cost more than a basic bike with a single front cog and a
cassette in the rear?

I'd practise on changing. Learn to change just before you need the lower
gear (ie. before the stall).

And, if you don't fully understand which gear positions are doing what, ask
someone to explain. (your bike, like almost every bike with 3 front chain
rings will have a lot of overlapping gear ratios, the trick is to know
roughly how it works out on your bike, not necessarily every detail of every
ratio).

Quoted message said:

Quoted message said:

You've already got a basic bike with a single front cog and a 7-speed
cassette in the rear. It just happens to have the option of a couple
of extra front cogs.

All you need to do to replicate the basic 7-speed thing you're
looking for is to not use the front shifter.

True, but a single ring bike would probably have wider spacing on the
back, so it might still make sense to change the cassette to a
Shimano Megarange or something.

Which is OK, unless the derailleur is a small cage one, whereupon a new rear
derailleur is also required, so the bill becomes:
wide range cassette - say £15
rear derailleur - say £15
new chain (longer) - say £10.
mechanic time - say £25 (lots more if central London ?)
Total - £65

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Stuart Millington said:

My bike, is a £100 cheapo from Decathlon (as I may have mentioned
before, sorry). But, I really haven't got the hang of the 21-speed
de-railer(!) gears - I sort of stall whenever changing down whilst
going up a hill - and would prefer something more like an old 7 speed
cassette hub.

as others have said need to change earler or get a better rear derailer,
cheap ones tend to fail to change down, under load.

Quoted message said:

Is it worth talking to the LBS about re-fitting this thing or would it
cost more than a basic bike with a single front cog and a cassette in
the rear?

thing to rember is that you don't have 21 gears but 7 gears with 3
ratios, rather like 4X4 cars have two ratios of 5 gears.

and the ratios over lapp heavly so only two gears or so either side of
the 2nd ratio.

its easyer on the gears if you keep to the lower gears on the 1st ratio
and to higher gears on the 3rd ratio.

roger

Nigel Cliffe said:

Jim Higson said:

Clive George said:

"Stuart Millington" <[email hidden]> wrote in message
news:[email hidden]...
>
> My bike, is a £100 cheapo from Decathlon (as I may have mentioned
> before, sorry). But, I really haven't got the hang of the 21-speed
> de-railer(!) gears - I sort of stall whenever changing down whilst
> going up a hill - and would prefer something more like an old 7
> speed cassette hub.
>
> Is it worth talking to the LBS about re-fitting this thing or would
> it cost more than a basic bike with a single front cog and a
> cassette in the rear?

I'd practise on changing. Learn to change just before you need the lower
gear (ie. before the stall).

And, if you don't fully understand which gear positions are doing what,
ask
someone to explain. (your bike, like almost every bike with 3 front chain
rings will have a lot of overlapping gear ratios, the trick is to know
roughly how it works out on your bike, not necessarily every detail of
every ratio).

Quoted message said:

Quoted message said:

You've already got a basic bike with a single front cog and a 7-speed
cassette in the rear. It just happens to have the option of a couple
of extra front cogs.

All you need to do to replicate the basic 7-speed thing you're
looking for is to not use the front shifter.

True, but a single ring bike would probably have wider spacing on the
back, so it might still make sense to change the cassette to a
Shimano Megarange or something.

Which is OK, unless the derailleur is a small cage one, whereupon a new
rear derailleur is also required, so the bill becomes:
wide range cassette - say £15
rear derailleur - say £15
new chain (longer) - say £10.
mechanic time - say £25 (lots more if central London ?)
Total - £65

I don't know about a new derailleur. The capacity lost in front would
probably be at least the same as that gained in back. Unless the cassette
had a very tight ratio to start with, I'd say you could probably keep the
same chain and rear mech.

Say, going from:
triple front: 22-33-44 & back: 14-28
to:
single front: 33 & back: 11-34

The original setup would need a rear mech with a 36t capacity, whereas the
second setup needs 23t, so keeping the old mech would be more than enough.

Stuart,

All you have to do is learn the technique!!
It will take a bit of practice but its not rocket science.
Try and do your gear shifting when you are only pressing lightly on the
pedals, practice on a flat bit of road going up and down through the gears
and forget about the front cogs if you have more than one (just leave it on
the middle one). Then all that's left to do when you are riding normally is
to try and anticipate when you will need to change gear and do it before you
have to start pressing hard on the pedals.
Even these cheap derailleur set ups work well and reliably if set up
correctly by the shop.
BTW it would not be economical to upgrade but you can buy a Triban 5 from
Decathlon for about 260 quid and that's got a nice trouble free hub gear.
Good luck, and hang on it there. It will all come together!!

SW

Simon Brooke said:

Let's just get out terminology straight.

....

Quoted message said:

Entirely separate from this line of development is the epicyclic or hub
gear, in which a single front chainwheel drives a single rear sprocket,
which in turn drives a train of sun-and-planet gears inside the body of
the hub body.

Sorry, yes, this is what I meant. Doh!

Quoted message said:

The other significant difference between the two systems is in use. On a
(good) derailleur system you can change gear under full power (although
it's kinder not to), but you can't change gear at standstill. Again, this
suits racers. With an epicyclic it's usually not a good idea to change
gear under full power, but you can change gear when freewheeling or at
standstill.

Yep, it's the ability to change gear instantly when freewheeling or at
standstill (after not predicting a required change in advance) that
would help at the moment. Especially at a junction after not changing
in advance and knowing I'll be starting off in the wrong gear and
vaguely worried until the change completes with the current system.

As others have said, I guess I need to learn how to use the current
gears properly and I haven't used the bike enough yet. Still too used
to hub/single gears. At least the weather's getting better and I may
start getting some practice in soon.

Thanks all.