Riding an audax on a Brompton

[L CC]

It appears HK and LW&B of this parish are doing LEL on Bromptons. HK has had tyre trouble & Tweets she now has a new 20" tyre for Casper.
I thought Brompton wheels were 16"...

HK, LW&B & teethgrinder are on Moultons- Casper is a Moulton- a white one.

[LittleWheelsandBig]

There were at least 6 Moultons at LEL; Julian on his Double Pylon, Martyn (first year of distance) on a TSR and another bloke on a TSR with a lot of bags.

[nashd]

Thanks – I’ve just stumbled across these replies.  I thought I was subscribed to the thread, but must have missed a notification.

Still trying to decide which version to buy.  I definitely think the 6 speed we tried wasn’t riding that well – it had a Schmidt dynohub and H bars.  Not sure what the cause was, but it didn’t freewheel.  We did a roll-down comparison with a 3-speed M, and that romped ahead.  It also felt better on the climbs, and there was less flex/twitch when honking out of the saddle.  Is it possible there’s more friction with a 6-speed? I checked for rubbing brakes etc.  If it was me I’d probably go for a single-speed or 2-speed. 

Was also able to try a Rohloff conversion with ti ends.  I’ve never ridden a bike with such a low gear before!  It’s too expensive for what it would be used for, though.  Also considering some of the other conversions such as 8-speed Alfine, but there are pros and cons with all those.

It looks like a 6-speed with lowered gears will be chosen, but the demo bike’s performance was a bit off-putting.

Yes, I saw a few pics of Moultons on LEL – even Teethgrinder had one!  I followed LEL on the forum.  I’m full of respect for everyone who rode it…especially anyone on a Brompton!

[LittleWheelsandBig]

Small wheels need free-rolling tyres more than big wheels. It is possible that the tyres and pressures were different between your test bikes.

teethgrinders very first LEL was on a Moulton, so something of a homecoming for him.

[nashd]

The 6-speed Brompton had the standard Brompton tyres, and the 3-speed had Marathons, which Brompton seem to suggest are slower.  When we had the 6-speed on demo I had to put some air in the tyres, so tyre pressures shouldn’t have been too different.  The roll-down test wasn’t exactly scientific, but it confirmed what I’d been experiencing – before then I thought maybe it was just the nature of the machine.  Are any of the Brompton configurations known to be slower/faster than others?  Obviously, the S is more aerodynamic than the M or H, but do the different hubs etc make a difference?  Is the 6-speed generally a bit lethargic, or did we possibly get a bad demo bike?

I’ve read Teethgrinder’s report of his first LEL, but didn’t know he used a Moulton.

[Biggsy]

H gives a more upright position than M, doesn't it?  If so, of course the H will be slower in a roll down test.  Anyway, it's not a bad hub and its drag is insignificant compared to tyre rolling resistance, let alone air resistance.  None of your tests have been fair to the hub, in my opinion.

Even in a like-for-like test, you don't test the drive resistance of hubs in a roll down, only the freewheel resistance.

[hellymedic]

It appears HK and LW&B of this parish are doing LEL on Bromptons. HK has had tyre trouble & Tweets she now has a new 20" tyre for Casper.
I thought Brompton wheels were 16"...

HK, LW&B & teethgrinder are on Moultons- Casper is a Moulton- a white one.

I sit corrected.

[tkatzir]

Way back in 2007 ... a guy on a Brompton dropped me ... during PBP ... he passed me on a descent

PBP07 was Tal aka tkatzir.

Yeah, I guess it was me.

I was young (read: foolish...) back then.


The main modifications for my S type B: A double chainset on the front (50/33) and Ergon grips.
The rest was stock.
I was using the standard Schwalbe Marathon tyres.

Tal.

[hellymedic]

I did the Gridiron 100km on a Brompton; it was not an AUK event at the time.

[Bromptoneer]

I've done a few 200km's on a H type and M type, both were very comfortable both were very slow compared to my fixie.

I'm now planning my next 200km on a 2 speed with a super duper lightweight front rim. The difference the sealed bearing-ed hubs front and back have made a MASSIVE difference to the rolling and the lower bars of the S type reduces air resistance MASSIVELY.

I think it feels faster than my fixie bike now.

[rogerzilla]

Even with the best tyres in the world, a 16" wheel rolls much worse than a 700c because it converts  road irregularity into more energy-wasting up and down movement.  There is no appreciable drag from any internally geared hub when freewheeling, so the 6 speed would not perform worse in a coastdown test (unless it had very tight axle bearings, which would manifest themselves by turning the cranks forward if you lifted your feet clear; a sure sign of bad bearing adjustment in any SA hub).

The wheels are often so out of true that the brakes catch the rims, which would have something of a slowing effect.

[Bromptoneer]

Even with the best tyres in the world, a 16" wheel rolls much worse than a 700c because it converts  road irregularity into more energy-wasting up and down movement.  There is no appreciable drag from any internally geared hub when freewheeling, so the 6 speed would not perform worse in a coastdown test (unless it had very tight axle bearings, which would manifest themselves by turning the cranks forward if you lifted your feet clear; a sure sign of bad bearing adjustment in any SA hub).

The wheels are often so out of true that the brakes catch the rims, which would have something of a slowing effect.

Interesting, I've had 4 Bromptons with different front hubs as well (dyno and lightweight) and I've not had any out of true wheels.

[Biggsy]

My Brompton wheels were supplied untrue, and the dishing of the rear was so out that I thought it was deliberate.  One rim tape was missing as well, proving that the builders' attention to detail is lacking.  Shame, because it's such a great bike overall.

Anyway, I'm thinking about rebuilding with different spokes and perhaps even different rims.  I hear Brompton have a new lighter version of their lightweight rim.

[Bromptoneer]

My Brompton wheels were supplied untrue, and the dishing of the rear was so out that I thought it was deliberate.  One rim tape was missing as well, proving that the builders' attention to detail is lacking.  Shame, because it's such a great bike overall.

Anyway, I'm thinking about rebuilding with different spokes and perhaps even different rims.  I hear Brompton have a new lighter version of their lightweight rim.

Oh dear, that's not very good is it? No one on the yahoo group has mentioned this.

I've just got a new lightweight front rim for my S4L and it is different and the rim tape is a far superior quality. The bearings are so silky smooth it's lovely to spin it it. I just hope they stay that way over winter.

[rogerzilla]

The bits of production that Brompton outsource, i.e. frame painting and wheels, also give the most problems.  The paint on mine ws appalling - it was rusting and flaking off within a year despite being ridden only in the dry.  I had to get it re-enamelled,  Apparently the later "satin" paint finishes are even worse.

[Bromptoneer]

The bits of production that Brompton outsource, i.e. frame painting and wheels, also give the most problems.  The paint on mine ws appalling - it was rusting and flaking off within a year despite being ridden only in the dry.  I had to get it re-enamelled,  Apparently the later "satin" paint finishes are even worse.

Yes I agree, the satin paint is awful just awful. Thankfully mine are work horses and I'm not too bothered about the paint scuffing and rusting where the cables rub. Good job really as it has rubbed thru in less than a month on my B's, maybe I'm less careful than most owners?
I did have a pre 2004 in gloss red, the gloss did seem to be more robust than the satin.

[Bromptoneer]

The 6-speed Brompton had the standard Brompton tyres, and the 3-speed had Marathons, which Brompton seem to suggest are slower.  When we had the 6-speed on demo I had to put some air in the tyres, so tyre pressures shouldn’t have been too different.  The roll-down test wasn’t exactly scientific, but it confirmed what I’d been experiencing – before then I thought maybe it was just the nature of the machine.  Are any of the Brompton configurations known to be slower/faster than others?  Obviously, the S is more aerodynamic than the M or H, but do the different hubs etc make a difference?  Is the 6-speed generally a bit lethargic, or did we possibly get a bad demo bike?

I’ve read Teethgrinder’s report of his first LEL, but didn’t know he used a Moulton.

My H type is much much slower than my S type. But, my S type has a new front super light wheel with sealed bearings. Whereas my H type has a dyno hub, M+ tyres, schlumpf mountain drive. Whilst most of these only add a bit of inefficiency each..the accumulation is noticeable. The upright position and massive gear range and lower possibility of punctures should in my mind outweigh the inefficiencies.

That said, I have started to prefer the S2L (technically S4L) because it feels more efficient. I've only just started building my mileage up again after 6 months off the bike due to injury. I'm planning on using the S type for my next hundred miler and will hopefully be able to get under 11 hours this time.

[Bromptoneer]

Season of Mists booked and paid for. I'm planning on using my H3L with Schlumpf Mountain Drive.

[rogerzilla]

There's a fair bit of drag from two epicyclics.  A cheap (although seemingly warped) way to improve efficiency is to replace the SRF3 mechanism with an old AW mechanism from eBay - no need to rebuild the wheel.  It weighs a lot less - even in its steel shell - and runs much better.  The downside is that you get some oil seepage, but people coped happily with that for 80 years or so. The SRF3 is not my favourite hub.

[Biggsy]

I wouldn't want an AW again after suffering its neutral gear in my old days with Sturmey Archer roadsters.  You don't have to worry about slight mis-adjustments and mis-shifts with the SRF3.

http://sheldonbrown.com/sturmey-archer_3-spd.html:

The AW and its near relatives also have a neutral gear, and if the cable is misadjusted, these hubs can drop out of gear. Jobst Brandt has, in addition, described a tendency of these hubs to slip out of high gear into neutral in a hard sprint -- though this problem does not occur under more usual conditions of use.

http://yarchive.net/bike/sturmey_archer_hubs.html:

What may not have happened yet, is that in top gear, even with a
perfectly adjusted and serviced hub, the driver can pop out of gear,
leaving you free wheeling forward.  If you are standing when this
occurs, it always causes a summersault.  This is why these gears are
not used in sports or hard touring.

[rogerzilla]

Jobst Brandt doesn't like SA hubs.  The particular failure mode he talks about is caused by wear of the planet pinion pins and the clutch and can be cheaply avoided with preventive maintenance (I always change these parts for new unless they look pristine).  I accept that under very high torque is may be possible to induce slipping in top gear, but I'm a real pedal-masher and I've never done it.

The AW was designed this way so that the parts prone to wear could be cheaply replaced, as it was intended as a general-purpose gear for utility bikes.  All other SA hubs of the era (more aimed at racing - British cyclists did not really use derailleurs until the 1960s) had trapezoid dogs on the planet cage to engage the clutch, and are not prone to slipping at all in top gear.  ironically these don't wear anyway, as the contact area is much larger; I rebuilt a 1939 AM and the clutch looked new but was original - the older parts have a distinctive titanium colour to the case hardening due to an obsolete (non-H&S) process.

The SRF3 has four problems:

1. It runs in grease, which loses you 1-2% in efficiency and means it needs to be opened up for a complete dismantling occaisonally
2. There is a part that tends to rattle after a few hundred miles
3. Much-increased complexity, so less reliable
4. Heavier

My commuting bike has an SRC3, the coaster brake version of the SRF3.  It does the job but it isn't as snappy or free-running as an AW.

[Biggsy]

I'd still be concerned about occasional slight cable mis-adjustments causing slipping into neutral gear, and I did used to get that.  I'm happy to trade a bit of efficiency for less worry.  Otherwise I'd be keen just for the weight saving.  A bit of oil wouldn't bother me.