KHS 747 Flite Owners with skipping chain/shifts:
I am seeing other owners of 2014 KHS Flite 747's on this forum complaining of the same "skipping chain/shift" problem I experienced with mine.
I have your solution.
I ordered and picked up my KHS 747 Flite XXXL bike last month and immediately on the first ride the chain skipped mysteriously when giving the extra long 200mm cranks some forward pressure to pedal. I could lightly pedal with no skipping, but any real pressure on the pedal- even moderate- made the chain "skip forward violently". I realized this only happens when on the 52 tooth front big chainring. It never skipped while on the small 36 tooth front inner chainring. My LBS tried all sorts of adjustments to the front and rear derailleurs plus adjusting the barrel adjusters and even tightening the crank arms. It still skipped. We then put another KHS Flite 747 chainring on my bike that was on another new Flite 747 XXL in the showroom- SAME problem- skipping chain.
Here is the defect and the solve: The issue is that the big 52 tooth front chainring KHS installs is far too weak for us Clydesdales-period. When putting pressure to pedal the big chainring "bends" and lets the chain pop off the chainring and jump a tooth- rather violently. My LBS then switched the KHS chainring to a bone stock Shimano 50 tooth big chainring and I had no skipping at all- I could even stand on the cranks with all my weight- perfect!
Here is my permanent solve at my own expense- I bought new forged 52/36 chainrings from Praxis Works (about $165). Forged chainrings are the strongest for us Clydesdales and Praxis is the only (yes only) manufacturer of a 52/36 forged compact 110BCD chainring set in the world- I know because I did many hours of research to find this out! Shimano is the only other maker of forged chainrings in the world, but only makes a 50/34 Ultegra combo, not a 52/36. I installed the Praxis 52/36 forged chainrings on my Flite and it is sheer perfection. The shifts are perfection and I can stand on the cranks and have zero chainring flex. The 50/34 Shimano Ultegra combo will work perfect BTW if you want a setup better for hill climbing- you will just need to have your front derailleur adjusted and moved a little lower on the frame to accommodate the smaller diameter.
So, KHS seems to have sourced very cheap chainrings for these "Clydesdale-specific" bikes. I took it upon myself to fix the issue and don't want to point fingers at them. Heck, I am just glad I was able to find a bike for my 6 foot 8 body! KHS should take note though and just ship these with better chainrings- probably 50/34's as the smaller diameter will be even stronger. Yes, It would be ideal if they installed forged chainrings for us bigger folk, but that would add $100-$150 to the price. As I proved, even a mid-range Shimano 50 tooth stamped chainring was better than the stock KHS chainring.
So, if you bought a 2014 KHS Flite 747- change out the chainrings- both if you can afford a new forged set, but at least replace the 52 tooth stock one with a 50 tooth "standard" chainring. When I had the Shimano 50 tooth and the KHS 36 tooth combination on while waitng for my Praxis chainrings it seemed to shift just fine. If you cant afford that, have your LBS change the 52 tooth to a stronger 50 tooth and have them file a warranty claim with KHS ad they should really cover your switch to a stronger chainring. I am not sure you can find a 52 tooth "stamped/machined" chainring strong enough to handle our weight as the extra diameter is what may be causing the flex. If you want to stick with the 52/36 stock setup like I did go with the forged 52/36 Praxis forged- they are strong and don't bend! This is NOT a commercial for Praxis- frankly I wish I did NOT have to spend my money to fix KHS's problem, but i wanted you all to know how I got my Flite shifting perfectly!
Good Luck All!