Originally Posted by
hihi2u2
Thanks, this is the best and the most brilliant answer ! I don't see the tools for widening or the service to widen on Kinetic website, I'll email them and see if they still do it.
Do you mind telling me how much did they charge for the widening ?
I think I will go for the Birdy III solution, I'm looking to fit a 56t chainring pairing with 11-28 but if there is a 9-32T then I don't need to go that big in the front. What speed are you running the 9-32T on, I'm just curious to find this cassette?
I didn't bought the widening only.
I bought a kit with the widening of the original titanium triangle of my superlight Brompton and a Rohloff rear wheel. It was in 2016 just before the brexit poll and the price for the kit was 1500GBP (I mention that it was before the poll that decided the brexit because just after that the GBP drop a lot against the Euro and the price of many Kinetics products increased. In my kit for instance a big part of the price is the Rohloff hub that Ben must buy in Euro).
If you ask Ben of Kinetics to provide you the complete kit, enlarged rear triangle with derailleur hanger + wheel, he might be interested.
For the cassette, the original gearing of the R&M Birdy Touring is 52t front and 9-32t (Sunrace 10s cassette) rear. It provides a good range of gear inches also for a Brompton since the Birdy Touring has 40x355 tires and the Brompton 35x349, so very similar wheel sizes.
This Sunrace cassette requires a special Sunrace hub, so I do not recommend it.
The best option is the 3T 9-32t Bailout cassette (made by Ethirteen, there is also an Overdrive version not very good for small wheel) which is now difficult to find in Europe,
there is only one online shop that sell it at a very low price
The other option is
Ethirteen Xcx plus 9-34t 11s cassette its only drawback is that there is no 10t cog, it goes directly from 9t to 11t (9,11,13,15,17,19,21,24,27,30,34) while the 3T Bailout has 9-10-11-12-13-15-17-19-22-26-32.
All those cassettes with a 9t smallest cog need a SRAM XD or XDR hub.
Another different solution is to use a SRAM Etap AXS 12s rear derailleur with the SRAM 12s 10-36 cassette. Its expensive but fully wireless, no cables at all which is nice for a folding bike.