jimboach

Hi everyone. This is my first post but i've been lurking for a pretty long time. Need some help and I'm hoping someone can help me finally comprehend what i'm actually trying to accomplish. My gf and I have had folding bikes for a while and have slowly upgraded. Finally, she's settled on a Dahon Ciao D5 mostly because of the looks. This is the look of the bike she's always wanted but after some time, she's gotten stronger and wants it to go much faster. Just to set the context, I have a Dahon Vector P8 and I'm doing various upgrades and seeing this, she's becoming frustrated how slow her bike is compared to mine. Now, i've done research on gearing and it seems pretty clear to me at times but I just want to confirm, with her 5 speed sturmy archer and her tiny 38t chainring, she spins out on the 5th gear pretty easily. 1 through 3 gears are virtually useless yet she's unwilling to give up the bike, itself. Where should I start to begin upgrading the speed on her bike? Keep in mind, she doesn't want to give up the frame itself. She likes the position...she just wants a lot more top end speed and even the very steep hills seem to be something she can conquer on 2nd through 4th gears. Should I increase her chainring size and associated parts or should I think about replacing her wheels and get rid of that internal hub? A normal RD is definitely a consideration but i'm just looking to you guys--Where should I start?

smallwheeler

this is a pretty good question.

first, there is no reason to dump the 5 speed hub. those hubs are very nice and have a good range and require very little maintenance. a 44t or 48t chainring will definitely satisfy her need for more speed, although, it's tricky to say which will suit her best without having her try it first. you could look at a gear calculator to get an idea of what the difference in development will be with larger chainrings, but still, that's math on a page and difficult to guess how it will feel IRL.

the easiest thing to do is change the sprocket on the IGH. i imagine its a 20t or 18t sprocket. try 15t, 14t...

Sheldon Brown's Bicycle Gear Calculator


my advice would be to call up a good LBS and explain what you are trying to achieve. they will be happy to sell you a new track type crankset and a chain. both of which you will need if her bike is like the one in this pic (the crank is a swaged on one piece unit. to change the ring, you need to change the whole crankset. also, depending on how much play you have in the dropouts, you will need a new, longer chain). also consider the interior diameter of the plastic chainguard. will it accommodate a 48t ring? good question.

again, the easiest thing to change is the rear sprocket.

jimboach

That's pretty great advice and along the lines of what I was thinking. I wasn't sure if I could even change the IGH sprocket but that's an entirely new idea I haven't considered but I'm 90% sure that's not going to achieve what she is looking for. I have also accepted that the plastic chain guard will have to go which isn't a problem at all. I think the thing is downright cheap looking and would prefer a common guard on the chainring itself. Tern Bikes has a chain protector that goes over a non derailleur chain as well, that I might consider. Regardless, losing that plastic piece of junk is not an issue.

Oh and that picture is pretty much my gf's bike except she has the all baltic blue one. I believe the above is the 7 speed. Her bike has been discontinued but the seem to be almost identical. Again, thanks for the advice and I think i'm going to start with the crankset with the biggest difference since most her gears are useless.

thugpipe

Actually the bigest difference would be made by the small sprocket on the hub, with the smallest impact on your setup, small wheeler was spot on. Reducing the rear cog by one tooth is like adding 3 teeth to the front. Best bang for your buck really, although it is a nice mod to have a real set of cranks the smaller the front chainring the better, in general.

dezzie

Also she could strip off any surplus weight like racks etc if she chooses, even changing a tyre to a lighter slicker one makes a difference, does she need the centre stand? switch it for a lighter single arm version, fit a lighter saddle, and not to be cheeky, best weight loss is herself, easier to lose 10lbs of your body than ten pounds off the bike and its probably cheaper, just sweat!

jimboach

The rack is part of the appeal. I just want her to better utilize the gearing. Losing weight is not an issue I really want to discuss with her..... But thanks for the potentially catastrophic suggestion!

alhedges

I bet it is!