Sunday, September 16, 2012

Q&A: Are folding bikes twitchy; individual cassette cogs

Dahon's Mu Undo
Q: Hi Jim, I'm thinking of getting a foldable bike, a one-speed model with a coaster brake to keep it simple. I'm considering Dahon's Mu Uno (photo). Have you test ridden it? I'm wondering if there will be a big difference in handling from my full size-wheeled bikes. I've heard people say that folders feel twitchy. I'm also concerned about the durability and serviceability of coaster-brake hubs.


 A: I’ve got a few folding bikes, Arnold and like them a lot. I have a Dahon from about 1980 and even back then they had a solid reputation for making nice-riding, convenient to use portable bicycles.

I've ridden some recent Dahons at bike shows but not the Mu Uno. On their website it looks like a quality one-speed model featuring a butted 7005-aluminum frame, nice aluminum wheels and solid components stem to stern including a Kinetix forged-aluminum crankset, Suntour folding pedals, Schwalbe Marathon tires and a Shimano coaster-brake hub.

I think you’ll love the Mu Uno if you get it. You’ll want to ride it on mostly flat rides probably, since it has only one 62-inch gear and a foot brake, but it should be wonderful for that. The little wheels feel quick to most people and that’s great, but they can feel a little too easy to accelerate and steer - because they're smaller and lighter - at first and that’s why some feel that folding bikes are twitchy.

Good folding bikes aren’t really twitchy or hard to handle. They just feel that way because you’re used to steering a big, heavier larger wheel. When you get on your little-wheel folding bike you need to relax and let the bike steer itself. It doesn’t need much input from you. Once you relax and stop trying to steer the bike like you do your other bikes it gets natural and feels quicker and nimbler.

Folding a Dahon takes seconds
I take my Bike Friday whenever I fly somewhere, and I find it takes about five miles or so to remember which bike I'm on and get into the groove of riding it, whether it’s going from the full size-wheel bike to the mini-wheel one - or the other way around when I return from the trip and get back on my regular rides.

Regarding coaster-brake hubs, they are usually very durable. I would estimate that in most cases you wouldn’t need to service a hub like that for as much as five years or even longer if you stay out of the rain. In many cases they just keep going and going with no maintenance. Typically you don’t use a folding bike as much as a regular bike or ride it as far, either, and that helps keep the wear and tear down too - as will riding it on flatter terrain where you won't have to brake all that hard or often. Hope this helps and let us know how you like your Mu Uno if you get it.

When talking about folding bikes, I have to point out one more cutting-edge bicycle, the Brompton, which is my preferred city bike because it folds in a blink, sports lights, fenders, rack, prop stand and a ingenious front bag. Here's Brompton's current line-up.

Q:  Hi Jim, I recently purchased a Lapierre Audacio with a Shimano Tiagra C4600 12/28 10-speed compact cassette (with 50/34 chainrings) and I’m finding the top gear is too low.  I’ve inquired with the shop that sold me the bike as to whether I could change the small cog from a 12 tooth to an 11 tooth but they advise that I’d have to change the entire cassette.  I had expected that it would be possible to source a single 11 cog for this cassette given that there’s an 11/25 cassette in the Tiagra C4600 range. 

Would you be able to advise if a single cog could be sourced for this?

Kind Regards,

A: I haven’t tried their cogs, David, but I’ve heard that Miche makes individual cogs for Shimano cassettes. Here’s a link to an online company called Universal Cycles that carries these so that you can learn more.

You’ll probably want at least two cogs, since if you remove the 12 and install the 11, you’ll have an 11 to 13 jump as your first shift, which will probably drive you crazy and feel like you’re missing a gear. Having a new 11 and a 12 should let you end up with 11/12/13/14 etc. which will feel right (you’ll want to disassemble your cassette and compare it to the Miche cogs to make sure they will fit correctly and let you build the cassette you want).

Another issue will be the Shimano cassette lockring (the last piece you install and tighten with the splined lockring tool - video shows lockring and removal with the lockring tool and chainwhip tool). The one you have is correct for a 12-tooth bottom cog. If you go to an 11-tooth cog, you will need a lockring made for an 11-tooth cog too, since the 12-tooth compatible lockring will be slightly too-large diameter and can prevent the chain seating on the smaller 11-tooth cog. (Tip: you have to look closely, but, so that you can tell the difference, the Shimano 11-tooth lockrings have a little "11" stamped on them.)

I'd compare the cost of the 2 new cogs and lockring plus shipping versus the cost of a new cassette, keeping in mind that your original cassette has resale value and that might make up the difference.

If I were you, I’d be strongly tempted to return to the bike shop and tell them you want to trade the original cassette for the right cassette for you. Even if they only give you wholesale pricing for it in trade, you might end up spending less than ordering the two cogs. Just clean your cassette up nicely so it looks like new.

I hope something here helps and enjoy that beautiful new bike!

In case you can't see it, here's a link to the video: