Hi everyone,

My Bike Friday is hurting my knees. The big difference between it and my main ride is the wider Q factor.

I have a pair of old TA Cyclotouriste crank arms on hand and was thinking of doing a wide range double (30 / 52). I put the numbers in Sheldon's Gear Calculator and it was a good match to the current triple.

I wanted to get some input before I go this route. My questions are at the bottom of the post.

Here's the bike:



And the current build as supplied by Bike Friday:


I will need a new front derailleur:



Just for information...the TA crank seems to have an ISO taper and does not seat as far up the spindle as the JIS taper cranks. These photos show the difference in seating depth (not tightened / just hand tight).





Questions:
1. What kind of front derailleur do I need? Brand / model please. Suntour braze on road front derailleur are pretty cheap. I have a soft spot for Suntour.
2. Will the current rear derailleur take up enough chain slack?
3. Is there an issue with function or the chain slipping between the chainwheels on the very wide range? (Peter White had something about that on his site.)
4. I know I will have to experiment with the BB length. Any issues with installing ISO cranks installed in JIS taper BB?

I'm all ears for suggestions or other solutions. I just need to lower my Q factor and I'm not tied to this solution.

Thanks a lot,
Dave