Originally Posted by
wolf33
Please forgive my general ignorance on this topic, I've spent the better part of the last two days referencing older threads and trying to confirm, but figured it would be best to ask the experts here to be certain.
I recently picked up a Dahon Speed Uno. I live in an apartment on the third floor and wanted something I could transport relatively easy (both up the stairs and in my car). The idea was to get back into biking, since I really haven't been on a bike since I was about 16. I also intrigued by the simplicity of the Speed Uno's design and the generally positive reputation Dahon had. No gears meant less things for me to break or have to fix down the road.
I've enjoyed riding it so far, and have been pushing myself to go a little further each day. I also realize being surrounded by hills that this bike was not intended for going up hills. I can't say I completely mind this, it's definitely a great workout for my legs, and this is not the only reason I've recently considered an upgrade. The other reasons are that I think it would be nice to have the option of getting this bike moving a little faster than stock form, and if it's possible to have two gears without having to manually shift them or run cables (i.e. SRAM Automatic), I could really see myself benefiting from such an upgrade. I do understand there are other variables involved with how fast a bike can go, however, I would imagine that freeing up the energy I'm presently using on hills might translate into more power on flat roads.
What I'm trying to confirm is exactly what is needed to complete the upgrade to an automatic 2-speed system to help me justify the costs involved. Based on my research and extremely limited knowledge, I was looking at picking up
this SRAM 2A hub with the coaster brake, hoping it would be a close to direct fit to the setup I currently have on my Speed Uno. I also had the following questions:
- Based on this hub configuration and my current platform, would I also need a new rim or completely new tire/rim combination? I see that some people on here have ordered complete setups from Universal Cycles, is this the way I should be leaning?
- Is the 36h model w/rear coaster brake the one I should be looking at, or does it not matter based on the smaller size of my tire (20")?
- Would the chain I have on there now be sufficient for the upgrade or should this also be replaced?
- What is an estimated cost to for parts/labor to have this upgrade completed through a professional shop? There apparently is a decent shop down the street from me called Cycle Loft that might be able to do this, I just haven't called yet because I don't want to sound like a complete idiot.
I realize there are a lot of people who will say I should have just gone with a geared-model folder instead, and they're probably right, but I do enjoy this bike a lot and going through the process of upgrading and figuring out what works/doesn't will be helpful for me in the end. In the short period of time I've owned the bike and been on this forum I've already learned a lot more than I knew before. Any constructive feedback is welcome and greatly appreciated.
Any dual speed hub isn't going to give you a lot of flexibility in terms of gearing. Seeing that you are a recreational rider, use the same amount of money and get yourself a Shimano Nexus 3 (3 speed hub) with a coaster brake built-in. Not only it gives you a low gear to climb decent hills, it also gives you a medium and high gear for flat speeds!
The problem with a dual speed hub is that, you are forced to choose either a medium and high speed or low and medium speed. In your case, you need low and medium speed. The gearing of the Speed Uno is already considered "LOW" to fit and strong riders. Since you found the stock gearing too high for the hills, that means you need something like a 40" or lower gearing for climbing hills, which then forces you to have a lower than what you have now stock gearing on direct drive cruising on flats. This puts you say at the max of around 20 to 24km/h on the flats if you spin like a mad man. The best setup for a SRAM A2 is actually in the ranges of 60" to 84", which is towards the higher gearing side; suitably only for the fittest and strongest riders. I don't think the A2 fits you all that well since it will shift automatically too soon unless you had it modified to shift later. This applies to lower gearing setup. I tried the A2 on a Tern Duo and I really hated it for this auto shifting. It forces me to slow down on a hill which I can attack quiet nicely with my Sturmey Archer S2C equipped Duo. In fact, my Speed Duo rides better than the Tern Duo with the A2 due to the manual gearing selection, which is what I prefer anyhow. Having said that, the SRAM A2 works great for higher gearing setup on a folder, whereas the S2C for lower gearing setup since you can manually set to low and spin your way up fast or slow since it won't shift gears like the A2 does automatically and unexpectedly.
The Sturmey Archer S2C works well for extended hill climbing and fighting gail force head winds (Sadly that's my commuting route for most times!), but it's not a robust hub which requires some rigorous maintenance. I already killed one after 500 miles, though Sturmey Archer sent me a brand new internal mech free of charge and is actually working better than the original one. My S2C is geared for 40" on direct drive and 60" for high geared drive. The 40" is very useful on the 8 to 10% grades I climb to work as well as fighting insane head winds.
But in your case, I would highly recommend the Shimano Nexus 3 which gives you low, medium and high gears and has only 1 cable to deal with anyhow. You can configure
the Nexus 3 to run a low 33" gear, which is what a lot of recreational riders prefer to use to climb hills.