Double Chainring combos for touring an S6L in a hilly area ....

[Rohloff_Brompton_Rider]

I can always get a Stronglight double for not too much.

Yep, that's what I did on the wife's previous B and ebayed the oem B one for same price.

 

[TheDoctor]

I thought long and hard about what double to fir to the M6R before taking it touring Provence. In the end I couldn't be arsed. If a 33" bottom gear was too high, there's always walking...
I'd throw a cheap compact on, myself.

 

[Fab Foodie]

If a 33" bottom gear was too high, there's always walking...
.

A 50/34 would give me a 22" to 68" on the 34 which is pretty useable for about £50. With the 50T all the way to 100".
I think that is sorted.
Ah, just double checking BB width .... I'm not averse to fitting a new one ....

 

[TheDoctor]

I didn't end up walking *all* that much.
To be honest, I did actually have a chainset to hand, so I could have fitted it. But I went for a ride to the pub instead. It seemed like a better idea at the time...

 

[Fab Foodie]

And it's the cheapest option by far. The yahoo Brompton wiki page has a list of the parts required, which is basically; a ring, 5 spacers (or 10 if they've not got the right ones in stock), 5 long ring bolts, BB spacer and an hour of your time.

Words of warning though, once you you can get into the hills because of the increased gearing - you will start contemplating more expensive options - and yearn for a Rohloff, been there done that. It's like a manual move double chainring starts you off down a path of addiction.

How does the BB spacer work then?

 

[Fab Foodie]

And a proper BB.

What do you recommend oh learned one?

 

[Rohloff_Brompton_Rider]

Simples, remove BB, slide a 3mm spacer onto drive side cup of BB and refit. Sounds too small to make a difference on (older) bb's but it's enough to clear the fold.

 

[albion]

I really cannot see there being a problem getting the Rourke into a C1, especially if you have no passengers.

Push the, tilted towards window, passenger seat fully forward, and remove the bike front wheel. If need be, remove the saddle post.

 

[TheDoctor]

That is a good point well made. We recently got three people, three cases and a road bike into a Toyota Yaris, so a road bike and driver into a C1 shouldn't be impossible.

 

[Fab Foodie]

That is a good point well made. We recently got three people, three cases and a road bike into a Toyota Yaris, so a road bike and driver into a C1 shouldn't be impossible.

I'll let you know! Full guards and rack fitted just for fun ....

 

[Fab Foodie]

I really cannot see there being a problem getting the Rourke into a C1, especially if you have no passengers.

Push the, tilted towards window, passenger seat fully forward, and remove the bike front wheel. If need be, remove the saddle post.

Yep it fits just fine .... Options options ....

 

[Fab Foodie]

Guys
Gonna get a Stronglight compact double and might as well fit a new BB and chain while its in pieces.
Can I just check ... What lengthy Shimano or similar BB do I need to order?

 

[12boy]

You can fit the new Stronglite to the existing BB and see if the chain line is right. Then measure the old one and, if needed add or subtract from its length until you feel it is right and buy that. The crank arm really drives the BB length. I replaces my single speed with a 119 and it has worked fine with both a Sugino RD2 and the original Brompton 52 tooth. There is a calculation for chain line that goes: Measure the width of the seat tube and divide divide by half. Measure from the left side of the seat post to the chain ring and subtract 1/2 of the width of the chain ring from that number which gives the exact distance from the center of the seat post to the chairing. Measure from the inside of the rear chain stay on the right to the cog and subtract that number from 1/2 off the total width of the distance between the chain stays. In the case of 2 chain rings and 2 cogs I would probably go to the distance between the 2.

 

[Arellcat]

According to Spa Cycles, a Stronglight Impact (and the similar Spa/Sugino XD-2) uses a 107mm BB. I'm pretty sure it's a JIS taper. Of course, the thing to watch out for is the chain getting jammed on or behind the swing arm bolt and bracket as you fold your Brompton, or indeed as you try to unfold it. The inner chainring must sit a minimum distance out.

As an example, I measured my original Brompton BB spindle as 119mm, and the chainline was 43.2mm. My FSA double (ISO taper) cranks onto a 110mm (JIS) bottom bracket, plus a 2mm spacer behind the right-hand BB cup, gave a chainline of 43.5mm for the inner chainring, on which I do 95% of my riding. The chainline for the outer chainring was awful, but it didn't really matter.

I ended up having to replace the cranks with similar but using the Octalink v1 interface, and I can't remember the BB spindle length for that.

 

[12boy]

i have a Xootr Swift as well as a Brompton, and was curious about crank weights so I checked. The Swift has some 130 BCD no-name crank and I weighed it, a Campy Nuevo Record, an old Avocet triple and a Sugino RD, all without chain rings. I was surprised to learn the were all within 10 grams of each other. I have not weighed it but for the Brompton I've returned to the original swaged crank and it feels quite a bit lighter than the other 4. to compare I would have to weigh them all with 52 teeth chain rings since the B's is one piece.