Brompton (narrowed) SA front hub brake: Brucey question?

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SA_SA_SA
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Brompton (narrowed) SA front hub brake: Brucey question?

Postby SA_SA_SA » 13 Nov 2019, 11:28am

I have the (now obsolete) narrow Greenspeed front hub brake for the Brompton* :----

*[url]review of said brake | http://www.atob.org.uk/bicycle-accessor ... hub-brake/[/url]

this seems to have been excessively narrowed resulting in more work than necessary? and a harder wheel build? due to narrow 'flange' to 'flange' distance:

It looked to me that an approx 80mm OLN hub could be made by cutting out the narrow section of a off the shelf SA 70mm front hub brake thus leaving conventional flanges ?


NB in order to have a front dynamo I have made a Maus-style front roller from a sanyo dynopower and M6 threaded rod**, however if one was wanting dynamo and hub brake from scratch I think wider forks and a standard 70mm SA dyno brake would be better. **Its quite noisy when it picks up some sticky mud and requires cleaned(== roller re-smoothed)...
Last edited by SA_SA_SA on 8 Jan 2020, 9:38pm, edited 1 time in total.
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Brucey
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Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby Brucey » 13 Nov 2019, 11:46am

if you think you can make it fit between a set of Brompton forks, have at it, why not? I've not BTDT, so I can't comment except to note that OLN is not the whole story; e.g. the flanges need to clear the fork blades too.

cheers
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SA_SA_SA
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Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby SA_SA_SA » 17 Nov 2019, 5:54pm

Thanks.
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Gattonero
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Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby Gattonero » 21 Nov 2019, 8:00am

SA_SA_SA wrote:I have the (now obsolete) narrow Greenspeed front hub brake for the Brompton* :----

*[url]review of said brake | http://www.atob.org.uk/bicycle-accessor ... hub-brake/[/url]

this seems to have been excessively narrowed resulting in more work than necessary? and a harder wheel build? due to narrow 'flange':

It looked to me that an approx 80mm OLN hub could be made by cutting out the narrow section of a off the shelf SA 70mm front hub brake thus leaving conventional flanges ?


NB in order to have a front dynamo I have made a Maus-style front roller from a sanyo dynopower and M6 threaded rod**, however if one was wanting dynamo and hub brake from scratch I think wider forks and a standard 70mm SA dyno brake would be better. **Its quite noisy when it picks up some sticky mud and requires cleaned(== roller re-smoothed)...


It's not as easy and safe ad you'd think.
1, the dropouts are 5/16" or just under 8mm. To reduce the OD of the axle diameter, or to increase the ID of the dropouts means to weaken one part of the other
2, the forks were never meant to carry the load of an hub or disk brake, they're strong and proven reliable but doesn't mean you want to test them to fault...
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...

SA_SA_SA
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Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby SA_SA_SA » 21 Nov 2019, 1:21pm

Gattonero wrote:...
It's not as easy and safe as you'd think.
1, the dropouts are 5/16" or just under 8mm. To reduce the OD of the axle diameter, or to increase the ID of the dropouts means to weaken one part of the other
2, the forks were never meant to carry the load of an hub or disk brake, they're strong and proven reliable but doesn't mean you want to test them to fault...

1) Custom 100mm width Brompton forks are available. Although it is common to fit electric motors into widened Brompton forks commercially...
2) I don't think a hub brake is a problem, discs would be better with a custom fork I think but IMHO have no place on a folding bike like a Brompton as are too vulnerable to damage. I have heard of no problems from the greenspeed hub and forks.
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Gattonero
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Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby Gattonero » 21 Nov 2019, 2:31pm

SA_SA_SA wrote:
Gattonero wrote:...
It's not as easy and safe as you'd think.
1, the dropouts are 5/16" or just under 8mm. To reduce the OD of the axle diameter, or to increase the ID of the dropouts means to weaken one part of the other
2, the forks were never meant to carry the load of an hub or disk brake, they're strong and proven reliable but doesn't mean you want to test them to fault...

1) Custom 100mm width Brompton forks are available. Although it is common to fit electric motors into widened Brompton forks commercially...
2) I don't think a hub brake is a problem, discs would be better with a custom fork I think but IMHO have no place on a folding bike like a Brompton as are too vulnerable to damage. I have heard of no problems from the greenspeed hub and forks.


Yes you could fit a 100 hub on a Bromton, it does mess up with the folding, though, and you get a bad bracing angle between the nipple and the rim.
Altogether with a hub/disk brake, it all goes for premature failures.
I can't see any valid reason for not using the caliper brakes that are fitted as standard, after all the Brompton is a bike that's robust enough but like anything else, it does need the little TLC. To fit drum brakes "so I don't have to clean the wheels" will bring problems to the other parts. Just like in any other bike, ask those people that followed the trend of disk-brakes on road bikes, thinking that it would be the cure for any problem :(
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...

SA_SA_SA
Posts: 1836
Joined: 31 Oct 2009, 1:46pm

Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby SA_SA_SA » 21 Nov 2019, 2:47pm

Gattonero wrote:
SA_SA_SA wrote:
Gattonero wrote:...
It's not as easy and safe as you'd think.
1, the dropouts are 5/16" or just under 8mm. To reduce the OD of the axle diameter, or to increase the ID of the dropouts means to weaken one part of the other
2, the forks were never meant to carry the load of an hub or disk brake, they're strong and proven reliable but doesn't mean you want to test them to fault...

1) Custom 100mm width Brompton forks are available. Although it is common to fit electric motors into widened Brompton forks commercially...
2) I don't think a hub brake is a problem, discs would be better with a custom fork I think but IMHO have no place on a folding bike like a Brompton as are too vulnerable to damage. I have heard of no problems from the greenspeed hub and forks.


Yes you could fit a 100 hub on a Brompton, it does mess up with the folding, though, and you get a bad bracing angle between the nipple and the rim.
Altogether with a hub/disk brake, it all goes for premature failures.
I can't see any valid reason for not using the caliper brakes that are fitted as standard, after all the Brompton is a bike that's robust enough but like anything else, it does need the little TLC. To fit drum brakes "so I don't have to clean the wheels" will bring problems to the other parts. Just like in any other bike, ask those people that followed the trend of disk-brakes on road bikes, thinking that it would be the cure for any problem :(


I can: the hub is more powerful than the dual pivot calipers, lower maintenance(pads last years....), more consistent, unaffected by rain, leaves rims clean ...... I do actually have the Greenspeed one which replaced a standard dual pivot. :)
As for spoke-rim angles : I presume you mean a 100mm hub, which I presume like the narrow greenspeed would be built one-cross, I have not heard of this causing problems to others and after all 100mm is still narrower than the Bromptons rear wheel (my rear is also built one cross after reading of a heavy person who fixed their Bromptons rear wheel collapses by building a 1 cross wheel). Do you have any actual reports/evidence of problems?
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SA_SA_SA
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Re: Brompton SA front hub brake: Official Velogical Brompton easier option...

Postby SA_SA_SA » 9 Dec 2019, 12:01pm

I think the Velogical's 'front fork fitting on Brompton Folding Bike' (steel forks only) rim dynamo is probably the simplest dynamo solution to wanting a front dynamo and hub brake on a Brompton: easier than widening forks....
https://forum.cyclinguk.org/viewtopic.php?f=5&t=134193#p1421021
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Gattonero
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Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby Gattonero » 8 Jan 2020, 8:23am

SA_SA_SA wrote:
Gattonero wrote:
SA_SA_SA wrote:1) Custom 100mm width Brompton forks are available. Although it is common to fit electric motors into widened Brompton forks commercially...
2) I don't think a hub brake is a problem, discs would be better with a custom fork I think but IMHO have no place on a folding bike like a Brompton as are too vulnerable to damage. I have heard of no problems from the greenspeed hub and forks.


Yes you could fit a 100 hub on a Brompton, it does mess up with the folding, though, and you get a bad bracing angle between the nipple and the rim.
Altogether with a hub/disk brake, it all goes for premature failures.
I can't see any valid reason for not using the caliper brakes that are fitted as standard, after all the Brompton is a bike that's robust enough but like anything else, it does need the little TLC. To fit drum brakes "so I don't have to clean the wheels" will bring problems to the other parts. Just like in any other bike, ask those people that followed the trend of disk-brakes on road bikes, thinking that it would be the cure for any problem :(


I can: the hub is more powerful than the dual pivot calipers, lower maintenance(pads last years....), more consistent, unaffected by rain, leaves rims clean ...... I do actually have the Greenspeed one which replaced a standard dual pivot. :)
As for spoke-rim angles : I presume you mean a 100mm hub, which I presume like the narrow greenspeed would be built one-cross, I have not heard of this causing problems to others and after all 100mm is still narrower than the Bromptons rear wheel (my rear is also built one cross after reading of a heavy person who fixed their Bromptons rear wheel collapses by building a 1 cross wheel). Do you have any actual reports/evidence of problems?


The Brompton is a folding bike that is meant to be carried by hand too.
Every kg you add results in discomfort, i.e. some train or underground stations require you to walk in crowded passages where you will have to hold the bike folded, and to carry more weight for several minutes on a daily basis is all but pleasant, and will get the user to put the bike in a shed and forget about it.
Standard caliper rim brakes are reliable, cheap, easy to deal with, light and will stop the bike reasonably well (because when it's raining you're not going to be a hero riding at crazy speed on 349mm diameter of tyres). Hence the drum brake is overkill in most cases.
The evidence of spoke failures is out there: old Brompton wheel would suffer from occasional spoke breakage by the nipple, or by the hub flange in the case of the hubgear with steel shell; while spoke failure with the smaller-flanged 2 speed freewheel hub is quite rare.
To make an effective drum brake you will end up with a hub flange the is over 70mm diameter, and I'm not even talking of an 80mm drum brake, which is a bad idea on a 349mm size rim.

Like said, you could use one if willing to accept the downsides. There has to be a reason why 1/2 milion bikes have been working well until now :)
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...

SA_SA_SA
Posts: 1836
Joined: 31 Oct 2009, 1:46pm

Re: Brompton (narrowed) SA front hub brake: Brucey question?

Postby SA_SA_SA » 8 Jan 2020, 9:33pm

Gattonero wrote:......The Brompton is a folding bike that is meant to be carried by hand too.
<1> Every kg you add results in discomfort, i.e. some train or underground stations require you to walk in crowded passages where you will have to hold the bike folded, and to carry more weight for several minutes on a daily basis is all but pleasant, and will get the user to put the bike in a shed and forget about it.
<2>Standard caliper rim brakes are reliable, cheap, easy to deal with, light and will stop the bike reasonably well (because when it's raining you're not going to be a hero riding at crazy speed on 349mm diameter of tyres). Hence the drum brake is overkill in most cases.
<3>The evidence of spoke failures is out there: old Brompton wheel would suffer from occasional spoke breakage by the nipple, or by the hub flange in the case of the hubgear with steel shell; while spoke failure with the smaller-flanged 2 speed freewheel hub is quite rare.

NB to avoid confusion I have corrected the OP from the possibly ambiguous <narrow 'flange'> to <narrow 'flange' to 'flange' distance>

<4>To make an effective drum brake you will end up with a hub flange the is over 70mm diameter, and I'm not even talking of an 80mm drum brake, which is a bad idea on a 349mm size rim.

Like said, you could use one if willing to accept the downsides. <5>There has to be a reason why 1/2 milion bikes have been working well until now :)
1) Even the light Bromptons aren't that light: I find the best strategy is to wheel until last minute, to minimise carrying the folded bike. NB An option is just that, an option: customers who want a front dual pivot can select that option....
<2> I did have the Brompton dual pivot: the hub gives better braking.The front caliper has the (small) disadvantages of needing blocks replacing, rims cleaning, replacing etc etc.... Also, the 180 U in the cable really annoys me, as a different (eg TT style or V) brake would need a smaller bend == less cable friction, whilst avoiding an upturned cable exit.
<3>But packing washers solve the problem caused by the thin 3 speed steel flanges...and the front hub is aluminium (so not thin)
<4> A hub brake of a given size is more effective in a smaller rim (more leverage) but note that the Brucey is happy with a 70mm front hub in full size 6xx mm wheels. NB I do have one so I know from experience that it is an effective hub brake in a small Brompton rim...
<5>Brompton offer hobsons choice of front brake so irrelevant (the dual pivots are a large improvement on the previous calipers but that is no reason to rule out an optional hub brake choice.... :)
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