Regearing a Brompton

In message <[email hidden]>, Ric
<[email hidden]> writes

Quoted message said:

I have a Brompton T6 with so-called "standard" gearing. How I wished I'd
bought the "low gearing" option!

I now want to reduce the gearing - can anybody advise me what sprocket sizes
I need to get to get near the "low gearing" option? Do I need also to modify
the chain length or can I get away with it unchanged? Is it possible to buy
an off-the-shelf kit from one of the Brompton specialists to make the
conversion?

Alternatively, would anybody advise fitting a Schlumpf speed drive (with
smaller front cog)?

Hi
Just been there and done it. Like you I wished I'd bought the lower
gearing. Just replace your standard 50 tooth chainring with a 44
(standard Brompton part, about £25). Remove a link from your chain and
spin up those hills.

Cheers

Bob
--
Bob Downie
Downie GeoScience Ltd.
please remove #n0spam# to reply directly

Ric said:

I now want to reduce the gearing - can anybody advise me what sprocket sizes
I need to get to get near the "low gearing" option?

According to the manual, with the derailleur on the 6 speed you look
like you're stuck with 13/15 sprockets, so I guess that means a smaller
chainwheel. The chainwheels seem to be pretty standard so there
shouldn't be much problem fitting something smaller.

Quoted message said:

Do I need also to modify
the chain length or can I get away with it unchanged?

Suck it and see: you've got the tensioner to take up the slack, and if
it doesn't do enough then it's a short job with a chain tool.

Quoted message said:

Alternatively, would anybody advise fitting a Schlumpf speed drive (with
smaller front cog)?

A colleague has a Mountain Drive (slightly bigger chainwheel) and is
very happy with it. A Speed Drive will give some overlap between your
sets of ranges, but a High Speed Drive should give more or less
continuous sets. It comes with a 29 tooth wheel as standard. This is
what I'll do to my L3 at some point if/when there's a cash surplus.

Quoted message said:

Does anybody have a BromSON?

Quoted message said:

I have a SON on one of my other bikes, and know that the fullsize version is
excellent. But does the tecnhnology translate well to the Brompton?

I have the standard smaller wheel version SON on my Brom. This needs a
slight spread of the forks, but that hasn't caused any problems and the
dynamo works fine. The SON XS for the Brom has been about for a while
now and I've heard zero instances of complaints, so I wouldn't hesitate
to get one if the full width one I had wasn't there. Brompton now
supply them as a standard option and they are not known for rushing
things into use untested, and Schmidt have an enviable quality
reputation that I doubt they're in a hurry to throw away.
Go for it!

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Thanks for the advice - splashed out today and ordered Bromson, titanium
telescopic seatpost (anybody want to buy a standard telescopic post?), 44T
front sprocket, and a Vitesse saddle.

Apparently best option with the Schlumpf is the speed drive on a 44T front
sprocket - this gives the best spread of gears (as opposed to a bigger front
sprocket and mountain drive). But I'll pass on that at the moment - maybe
something to add later if I really miss the topend.

In message <[email hidden]>, Ric
<[email hidden]> writes

Quoted message said:

Thanks for the advice - splashed out today and ordered Bromson, titanium
telescopic seatpost (anybody want to buy a standard telescopic post?), 44T
front sprocket, and a Vitesse saddle.

Apparently best option with the Schlumpf is the speed drive on a 44T front
sprocket - this gives the best spread of gears (as opposed to a bigger front
sprocket and mountain drive). But I'll pass on that at the moment - maybe
something to add later if I really miss the topend.

I'm interested in the standard telescopic post. Email me at the above
address minus the #n0spam# if you still have it.

Cheers

--
Bob Downie
Downie GeoScience Ltd.
please remove #n0spam# to reply directly