Front derailleur on a Bromptopn

[Tenkaykev]

Due to combination of age and anaemia I was really struggling on the local hills.
I swapped out the 50 for a 44 and it's made all the difference.
At first I didn't bother shortening the chain for a while as the tensioner takes up the slack, finally got round to it last week.
I spend most of the time in 2nd on the hub gear and going up and down on the derailleur. Don't usually go fast enough for top gear but the lowest gear on the steep hills is definitely useful.

 

[TheDoctor]

I can confirm that a double chainset works perfectly well, although like Fabbers I've not got a front mech.
I did try a 44T chainring, which in theory should have suited me well, as it pretty much moved the whole range down a gear.
What it actually meant was that my two most used gears involved a double shift to go between them...

 

[shingwell]

@Tenkaykev thanks that is a useful bit of experience to share. I live in a hilly area and have been wondering if 50->44 is a worthwhile mod for a combination of age and knee problems! Plus I don't like to pull on the bars too hard, feels like they could bend or maybe that is just an overactive imagination, nothing bad has happened (so far).

 

[Kell]

@Tenkaykev thanks that is a useful bit of experience to share. I live in a hilly area and have been wondering if 50->44 is a worthwhile mod for a combination of age and knee problems! Plus I don't like to pull on the bars too hard, feels like they could bend or maybe that is just an overactive imagination, nothing bad has happened (so far).

I've found it to be noticeably easier.

Like you I didn't really want to pull too hard on the bars and the hill near me is pretty steep. I have done it once in second when my chain pusher didn't work, but it meant standing up for a good portion of it (and I was blowing out my arse at the top). With the change, I could do most of it in 2nd seated, and the steepest part in the middle in can do in 1st and just rest a finger on the bars.

According to Strava, the gain is over 300ft in just over half a mile.

I can't find a good picture that shows how steep it is (or at least makes it look as steep as it feels to me) but it's one hill that consists of three inclines and two slightly shallower bits.
this is about the best photo I can find of the steeper middle section - and this is where I hit 40mph+ on the downhills.

According to my Strava feed, the KOM on this averages out at over 17mph... my best time averages out at 5.3mph.

If it wasn't for this part of my commute, I'd have been perfectly happy with the gearing.

 

[ukoldschool]

I still cant decide whether the 44T is better or worse.

It's not been a full week yet so it needs a little time for me to get adjusted.

I took a different route last night and couldn't really settle into a gear. 4th was too low and 5th not quite low enough for in town.

I think I'll persevere with it as I'm definitely liking the lower first gear - especially last night when I had 100kg of me, 12kg of bike, 5-6kg of my normal commuting backpack plus, because I was playing softball last night, my softball cleats, two softballs, softball glove, rain jacket, a softball bat, spare shorts and T-Shirt all in a C-bag.

Then when time comes to swap them out again, I might look at the smaller cog on the rear.

I think you are an ideal candidate for the 3 cog conversion....

 

[Kell]

I think you are an ideal candidate for the 3 cog conversion....

Oooh.

Tell me more...

(Please).

 

[Tenkaykev]

I've found it to be noticeably easier.

Like you I didn't really want to pull too hard on the bars and the hill near me is pretty steep. I have done it once in second when my chain pusher didn't work, but it meant standing up for a good portion of it (and I was blowing out my arse at the top). With the change, I could do most of it in 2nd seated, and the steepest part in the middle in can do in 1st and just rest a finger on the bars.

According to Strava, the gain is over 300ft in just over half a mile.

I can't find a good picture that shows how steep it is (or at least makes it look as steep as it feels to me) but it's one hill that consists of three inclines and two slightly shallower bits.
this is about the best photo I can find of the steeper middle section - and this is where I hit 40mph+ on the downhills.

According to my Strava feed, the KOM on this averages out at over 17mph... my best time averages out at 5.3mph.

If it wasn't for this part of my commute, I'd have been perfectly happy with the gearing.

View attachment 465768

That's some hill Kell, I see on the left in the photo someone pushing a bike.

 

[rualexander]

I have this clamp and several other and combinations of different derailleurs and cranksets and tried various combinations and options and can categorically state that it cannot work unless you give up on standard folding. Yes I tried that!

P.S. There should be no problem showing photos of the operation.

Sure, no problem,



Also video,


View: https://youtu.be/FUVr0y_KDec

 

[TheDoctor]

That's impressive.
I've no plans to fit a front mech myself, but my gut reaction would have been that it'll impede the fold, or stick out, or something.
And I'd have obviously been wrong. Chapeau!

Oooh.

Tell me more...[about the 3 cog goodness]

(Please).

IIRC it involves taking the existing two cogs off, then replacing them with 3 cogs (and two spacers) from a 10 speed cassette. You use a 10 speed chain, and alter the rear lever by filing a notch in it. It's a bit bodgetastic IIRC.

 

[u_i]

Sure, no problem,

Also video,

Thanks. I did not try the same derailleur as yours but I tried some other ones and they did not differ much between themselves. In any case, my derailleur would have to start out its swing out by ~5mm to drive side compared to now, I would have to increase the bottom bracket axle extent on the right side by that amount and I am not sure whether any of my derailleurs would be able to shift to the largest ring. In more detail, with the specific clamp, the crankset must be pretty much out to the drive side for the derailleur to be able to shift to the smallest ring, but then if you shift it too far out, it starts having problems shifting to the largest. Finally with all that push to the right I would have problems with the finger on the left fork grabbing the chainstay in the folded bike - the whole transverse size would go up.

P.S. My front gear span is more twice that your suggested 26-34-42, at 20-32-50, but I did not think it mattered this much for feasibility.

 

[u_i]

Maybe I can even be more precise in describing the problem with that adapter. Its clamp blocks the cage of the derailleur so that it cannot swing down to a position under the mounting point. On a bike with actual braze-on, the position of the derailleur for the smallest ring is with the cage touching or nearly touching the seat tube, under the mounting point. It is more serious for triple derailleurs with bulky cages than double with slimmer. All of this is additionally aggravated by the much larger seat tube diameter in Brompton than in non-folding bikes. I.e. I still think this clamp is a bad choice for mounting a triple, even if you somehow succeeded getting it to work - I still have hard time believing. Double setup is more forgiving.

 

[mitchibob]

Thanks for this thread. I recent just took a 44T with me for when I knew I was going after a climb, and switched over when I got near it (I did remove the link in the chain too, then when putting back the 50T, stuck in another quick link).

But after a while with riding with the 44T, it did annoy me that I was mostly in fifth gear outside of Wales, and that never feels quite as efficient as the direct drive ones. Also, constantly spinning out on decent descent. While the 44T let me get up the Bwlch with luggage, I did wonder if I'd get up some of the others I'd thought about doing (but ran out of time, accommodation, bottle) without a bit of a lower gear.

Hearing about doing the manual compact-type chain-set, I think for the big climbs, this could definitely be the answer to quickly restore something like a 50T at top so that you can pedal on the descent and keep more control and warmth, while being able to easily knock into the little ring before starting ascent. Am I being picky to want to find such a set with sensible chain-guard? ;-) It might even make a Brommie more Fred friendly (apart from the cattle grids). Maybe something like a 50/34 or something. That'd get me up Hardknott pass, right?

 

[u_i]

Am I being picky to want to find such a set with sensible chain-guard? ;-) It might even make a Brommie more Fred friendly (apart from the cattle grids). Maybe something like a 50/34 or something. That'd get me up Hardknott pass, right?

This is the typical route with modest challenges only. Indeed start from the chainguard side and there 50/34 Shimano Tourney seems to be an option. You can combine it with the SP8 adapter mentioned above and a SunRace thumb shifter.