Folding Bikes - Should I attempt to fit 369 Moulton rims on my Merc?

I'm at a place with my new Merc where I'm upgrading and lightening it with a singlespeed rear and pantour front hub. Made a real nice job of butchering my Ti Brooks b17 today with the Dremel. Saved 100grams yeah!

Anyway - I'm wondering about rims. The thing about fitting a nice light pair of Stelvio Lights to the standard ISO 349 rims is they are pretty small, losing a bit of overall circumference and therefore rolling efficiency. So I have this idea to build the new hubs into 369 Moulton rims and put some nice skinny Bridgestone tyres on them - the upside being I'll also be able to fit short reach roadie calipers, the downside being the fit; Or rather WILL they fit?

I'm not planning on rolling with any mudguards and the clearance on the front fork seems plenty enough - this is only really a 1cm difference from the axle - but the rear might be a bit tight...

I guess I'm just slightly worried about a costly mistake - rims and spokes (esp if I decide to go a bit mental and get some Ti ones) cost a lot if they're too big.

What do people think? There is I suppose, the Plan B of slightly smaller Birdy 355 rims, but the Stelvios for that size aren't the nice 1" skinny ones :(

[Edit] When it's a bit more ready I'll get some pics up

I'm at a place with my new Merc where I'm upgrading and lightening it with a singlespeed rear and pantour front hub. Made a real nice job of butchering my Ti Brooks b17 today with the Dremel. Saved 100grams yeah!

Anyway - I'm wondering about rims. The thing about fitting a nice light pair of Stelvio Lights to the standard ISO 349 rims is they are pretty small, losing a bit of overall circumference and therefore rolling efficiency. So I have this idea to build the new hubs into 369 Moulton rims and put some nice skinny Bridgestone tyres on them - the upside being I'll also be able to fit short reach roadie calipers, the downside being the fit; Or rather WILL they fit?

I'm not planning on rolling with any mudguards and the clearance on the front fork seems plenty enough - this is only really a 1cm difference from the axle - but the rear might be a bit tight...

I guess I'm just slightly worried about a costly mistake - rims and spokes (esp if I decide to go a bit mental and get some Ti ones) cost a lot if they're too big.


What do people think? There is I suppose, the Plan B of slightly smaller Birdy 355 rims, but the Stelvios for that size aren't the nice 1" skinny ones :(

[Edit] When it's a bit more ready I'll get some pics up

Hi pixel.

My question is why would you want to do this?

Take the rack off, the lights, and even (though it wouldn't suit me) the mudgards, but why mess with the rims. I doubt you'd save much weight, and I wouldn't have got rid of the srf-3 hears either.

That damned bike is as near perfect as can be once you change the brake blocks, oil the cables, and replace the plastic chain tensioner widget with a proper metal one. I bet you will pay more for the rear rim hub and spokes than you would for a spare merc wheel WITH a new gearbox. This sells for £45 by the way.

I love that damned bike, and think your plan is sacriledge mate.

:)

All fair points EvilV!

I suppose I have in inbuilt need to be different, to experiment, to tinker, to upgrade. Wanting to do something and needing to it are different things and I really want to do this. I see bikes in (uh-oh - possible pretentiousness ahead) in terms of aesthetics, of scultural form as much as by function and I guess this explains my plan - I think slightly bigger rims with tight clearances around the forks and rear triangle, with beautiful campag calipers will just make the bike pop that bit more, feel that bit more unique; using a Moulton size seems apt as one of the original innovators in smallwheel adult biking, and in some way going back to the roots of the bike.

I know there's the old adage '...if it aint broke don't fix it...' but we'd still be using stone wheels a la Flintstones if everyone heeded that advice. :)

Thanks for your words though - I need to hear things to keep me grounded every once in a while.
You're losing in the poll though ;)

That's ok Pixel, old chap. I know why you're doing it and appreciate the need to experiment. I hope it all goes well for you and that you're happy with the outcomes. Of course, I hope you have some niggles on the way - that's what you need to make the changes satisfying. I've made my own adaptations to the merc as you may know, only weight isn't what motivates me, functionality is. Just different sides of the same coin and good fun whichever side you play with.

Have fun.

As for the pole; with a total input of 7 opinions at this moment, and a score of 3,3,1 for the options, I think it's stretching it to say what the outcome is. Small number make such poles meaningless, two people could come in and change the outcome right around, but I'm sure you knew that already Huw.

:)

Hi Pixel - good project ! I'd start with std wheels and experiment with tyres (easy) and then if you still want to change rims use, the size change inconjunction with gearing tweaks. I've often wondered about the benefits of converting a brompton to single speed - apparently Andrew Ritchie likes this set up - its weird its never been marketed.

Question: what gear ratio will you go for
- low n easy (eg c 50-55") for fast traffic light take-offs (but you'd have to spin at speed) ?? OR
- Higher, like a roadie (eg 65"+ ) and expect to get out of the saddle for slower traffic light take-offs - (but overtake em later) ... ??

Just checked my rear rim Pixel... wobble, wobble, wobble.

Checked the spokes. Another one bust, but the first in a thousand miles or more. That's five I've done in, athough most of them happend at the same time after a long heavyladen ride with a broken one wagging about. This time I used a trick I learned about on the Bromptontalk list; I replaced it without taking off the wheel. It wasn't hard, and makes it a quicker job. Pull the tyre over; pull the tube out a bit so that the rim tape is exposed; pick it back with a screwdriver and get out the nipple from the snapped spoke. Then push in the new nipple; thread the new spoke, and screw it up reasonably taught. Replace the tape, tube and slip the tyre back onto the rim. This last step is much easier on these small tight tyres if you rub washing up liquid into the bead. You can get it right up to the last two inches without levers if you do this. One tweak with the lever and it was on again. Final check with the spoke key, sighting for trueness against the brake blocks as the wheel is spun, and the job is done.

Hi Pixel, I would stick with 349mm rims. You have much better tire options at that size and almost no downsides. I use Stelvios on my Birdy. They are cheaper than the 349 tires, but only because they have wire beads! Stick with the kevlar beaded 349s. I'm probably going to go down to that size on my Birdy!

Hi Pixel - good project!
Thanks - It's already shed a lot of weight with rack, guards, silly saddle adapter and dynamoes consigned to the parts bin. Also has flat bars and ergon grips. Oh and just a front brake... :)


I've often wondered about the benefits of converting a brompton to single speed - apparently Andrew Ritchie likes this set up - its weird its never been marketed.
It is odd when all you have to do is get the 2 speed version and remove the brompton derailleur. I think they're worried about having too many 'models' in the range, which with the combinations of bars, TI, racks, dynamoes I can understand. I guess singlespeed is still too niche, and that your average Joe sees the small wheels and feels it has to have gears to be a usable thing. We know different but we're in the minority non?

With Singlespeed (if set up right), I love the simplicity for urban riding - bikes are just that bit more dependable. Not sure I'll ever go back to derailleurs. I mean - the whole idea is essentially a hack. I hate the clunking, the snagging, the noise. Ideally I'd shed the tensioner too but this will bork the folding and unlike my Twenty, which I rarely fold, I do intend to use this to multimode™ about london.


Question: what gear ratio will you go for?
That's easy - about the same as on my Twenty and road bike which is around 74 which is just about right for me - you tend to spin out at around 28mph going down hills but most of the time it's good for most london riding and it doesn't feel too much of a trial except on the biggest hills.

So with 369 wheels that'd be 12t on the rear and 53 up front which is perfectly doable. on 349s I suspect I'd need an extra tooth up front - 54 is getting a bit big though isn't it?

I hope you have some niggles on the way - that's what you need to make the changes satisfying.

I undoubtedly will - and will likely share them as and when I get to them :)


I've made my own adaptations to the merc as you may know, only weight isn't what motivates me, functionality is.
And it's a neat ride. I think if I was wanting something for countryside touring, or to fly off and explore another country then I'd definitely go in that direction, but for scooting around london, all I really want is speed, easy hefting and minimum of things to go wrong. Ok so the rims thing doesn't really entirely fit there but I want better braking and since I don't need the clearances for mudguards it seems like a reasonable direction for a folly project bike at least. I am - however - unlikely to go *too* far and start drilling tiny holes in all the components... ;)



As for the pole; with a total input of 7 opinions at this moment, and a score of 3,3,1 for the options, I think it's stretching it to say what the outcome is. Small number make such poles meaningless, two people could come in and change the outcome right around, but I'm sure you knew that already :)

Yes... The poll is just a bit of fun. People love to click radio buttons! ;)

LP, this confirms your diagnosis of "folder compulsive, subtype WW".... it's fun to tackle a rebuild with unknown outcomes. I voted for "do it".

Can you climb Greenwich Observatory Hill with a 75" fixie? Is that slope the steepest long slope in London? What a view, though, on a clear day!. Alot of London geography fell into place for me, esp. that associated with the Age of Sail.

I plan to bring a Merc home on my next trip to Taipei.... why do I need bike no. 14 (in select locations from the Japanese Alps to Norwich)? Because 13 is unlucky?

If you do go with 369s, what will you do with the brakes?

Rear - no brakes. No cables to complicate the fold, less weight. I've run other bikes with just one before and find one is fine for me. Obviously on a fixie running one is complimented by leg-braking but even with a freewheel I've never really used the rear much.

Up front I want to use a light and strong short reach road bike caliper - dual pivot and not unlike the ones on higher end bromptons - but neater due to smaller reach and tighter tolerances.

Up front I want to use a light and strong short reach road bike caliper - dual pivot and not unlike the ones on higher end bromptons - but neater due to smaller reach and tighter tolerances.
I intend to switch Merc's brakes for road bike caliper ones - I thought they would work ok with existing rims - was I wrong then?
Check the folding with 369 rims - is there room for seat-post-pin when folded?
Do it and give us some pictures.

I intend to switch Merc's brakes for road bike caliper ones - I thought they would work ok with existing rims - was I wrong then?
Check the folding with 369 rims - is there room for seat-post-pin when folded?
Do it and give us some pictures.

I took the front caliper of my son's road bike and tried to fit it to the Merc when I first got it. The measurements were wrong and the caliper couldn't adjust to the rim given its mounting point. Unless you are very skilled, I'd try and stick to the Brompton double action calipers. They will fit given that the Merc is an exact measure for the B. I find that with Koolstop pads and decent lubrication in the cables, my brakes work acceptably now with their original calipers. I can stop as quickly as I need to on any hill. When I first got the Merc, it just sailed onward happily while I was squeezing the levers as hard as I could. The rims have worn in nicely and the softer pads make a HUGE difference to my stopping power. Now it stops; before it didn't.

I took the front caliper of my son's road bike and tried to fit it to the Merc when I first got it. The measurements were wrong and the caliper couldn't adjust to the rim given its mounting point.
Thank you EvilV for the information. So I'll have to take very accurate measures of Merc rim size/mounting point - or preferably make a small model where to try fitting brakes in a bicycle shop. My Merc brakes work still ok, but as they are the type that does not center, they are on my update list.

Rear - no brakes. No cables to complicate the fold, less weight. I've run other bikes with just one before and find one is fine for me. Obviously on a fixie running one is complimented by leg-braking but even with a freewheel I've never really used the rear much.

Up front I want to use a light and strong short reach road bike caliper - dual pivot and not unlike the ones on higher end bromptons - but neater due to smaller reach and tighter tolerances.

NYC has a lot of fixies riding around with front only brakes, and I watched one get into an accident. (Face into the back of a van, ouch!) Even an expert rider like you can get into a suddenly tricky spot, so consider carefully. The other downside is that you will quickly wear out the rim you worked so hard to put together!

Pixel could be pulled by a sharp eyed policeman too. Traffic regs say a cycle must have a rear brake unless it has a fixed wheel. Not that I expect anyone would ever notice or care. Things have changed in regard to observance of minor rules. In 1965 as a kid, I was given a police caution for riding a cycle without lights after sunset. Plod also tested my brakes and claimed they were inadequate.

That's easy - about the same as on my Twenty and road bike which is around 74 which is just about right for me
That's quite a high SS ratio for central london - I guess you dont do much stop-start traffic stuff ... or, if you do - Kudos :)

My calves are like great big hams ;)

ahh, then that was you racing around three buses queued at a stop on Oxford St.

Traffic regs say a cycle must have a rear brake unless it has a fixed wheel.
Britain yes. Other countries, perhaps not. Australia, one brake is fine.

I don't think that 369 wheels will fit in a Brompton rear triangle (specifically the chainstay bridge), don't know about a Merc.

Thanks for all the input people. I think I'm going to be conservative - partly out of caution and partly to do with availability of parts; couldn't get a 28h Pantour so have gone for 32 - the downside being that unless I'm up for drilling out my own spoke holes I can't get rims in 369 with the correct no of holes. The upside is I can get some black anodised Velocity Aeroheads with machined sidewalls which will look rather attractive I do so think - esp laced radially up front. Maybe the 369s are for another day - when I haven't got three other bike projects on the go!

lttlpxl

Thanks for all the input people. I think I'm going to be conservative - partly out of caution and partly to do with availability of parts; couldn't get a 28h Pantour so have gone for 32 - the downside being that unless I'm up for drilling out my own spoke holes I can't get rims in 369 with the correct no of holes. The upside is I can get some black anodised Velocity Aeroheads with machined sidewalls which will look rather attractive I do so think - esp laced radially up front. Maybe the 369s are for another day - when I haven't got three other bike projects on the go!

lttlpxl

That was undoubtedly the right choice. I'm still unsure whether to go with 349s myself. I assume there's no difference in performance or ride between a 369 and a 349, especially on a suspended bike. I was shocked to see that there is no Marathon Racer in 349, which is my favorite tire, so I might stick with the Birdy rims. Is the Primo Comet comperable?

I found narrow flange hubs, which lace up to small wheels better. The frustrating thing is that Chris King makes a narrow flange front and American Classic makes a narrow flange rear. This is the exact opposite of ideal, since AC rears have low ratings and high failure rates. Anyone know of any good narrow flange rear hubs?

I'm going for a small-flange 110mm OLN Phil Wood Keirin track hub for the rear, and spinning a freewheel onto that.
Not so sure about cassette hubs I'm afraid. My tip of the day for Brompton owners comes from Hubjub - a fixie specialist here in the uk; They say that you can fit a Phil Wood racing hub up front as they are narrow enough. This actually is probably good news for Dahon people too. I don't know about drilling or respacing the axles but too small is better than too big right?