On my review of my Bike Friday, I talked about the mediocre shifting. On of the possible fixes I mentioned was to replace the MicroSHIFT bar end shifters with Shimano shifters. The cost for the Shimano shifters is a bit over $100. But as I thought about this, I realized that the price of Shimano 10 speed bar end shifters is slightly more than the additional cost to replace all of the other parts needed to upgrade the drive train (Rear Derailleur, Chain, and Cassette) as well. So for about $200 - a bit less than twice the cost of replacing only the shifters, I can not only replace the bar end shifters, but the entire drive train, and move from MicroSHIFT 9 speed to Shimano Tiagra 10 speed. So what does all of this data that look like?

Component Part	9 Speed Price	10 Speed Price

Dura Ace SL-BS77 9-Speed Bar End Shifters	$114.60
Dura Ace SL-BS79 10-Speed Bar End Shifters		$ 94.28
Tiagra RD-4700 GS Rear Derailleur		$ 38.64
Tiagra 4700 11-34 Cassette		$ 49.92
Tiagra CN-4601 10-speed Chain		$ 21.98
Shimano Tiagra 4700 10-Speed 34/50t 165mm Crankset		$100.07
English 68 width RS500		$ 19.99


Cost to replace only the current Bar End shifters (10 speed upgrade)	$114.60	$203.90

Cost to replace all, including the Crankset / Cost to upgrade the Mondonico		$323.96

Added cost to upgrade new Bike Friday from 9 Speed to 10 Speed		$ 89.30

So replacing the shifters will cost $114.60, while replacing the shifters AND the rest of the drivetrain parts (Derailleur, cassette, and chain) to upgrade from 9 speed to 10 speed will cost $203.90. That is only $89.30 more. In other words, replacing only the shifters, and staying with 9 speeds will cost more the over half of the total upgrade cost.

However, the replacement cost for cassettes and chains when doing maintenance, is quite a bit higher for 10 speed components than it is for 9 speed: ($49.00 + $21.89 vs. $10.48 + $9.23 or $70.89 total vs. $19.71 total. More than 3 times as much.

Note: The cost estimates listed above do not including the cost of replacing either the front derailleur or the crankset. This is because my internet research tells me that they should work fine with the other 10 speed parts listed.

Of course if I had the foresight to see this when I specified the bike in the first place, I might have been able to do this in the first place. The following table shows what it might have added to the price had I known then, what I know now.
I included an additional item at the bottom to include the cost of the R9 read Derailleur as well, since I had to do this after delivery before considering all of this.

Parts used on my bike as delivered	Price	half of cost
MicroSHIFT 9 Speed Bar End Shifter Set	$77.15	$38.58
Sunrace 11-34 9 speed Cassette	$20.95	$10.48
microSHIFT MarvoLT M46 Long Cage Rear Derailleur	$12.00	$6.00
KMC X9.93 9-Speed Bike Chain	$18.45	$9.23

Total Cost / Half cost, assumption of credit	$128.55	$64.28
Cost of Tiagra parts		$ 203.90
Presumed final cost: Cost of Tiagra parts less credit		$139.63
Less cost of microSHIFT R9 read derailleur I wouln'd have needed		($20.00)
Presumed final cost: Cost of Tiagra parts less credit and R9		$119.63

	Bottom Bracket Data

	English 68 width-Bottom Bracket Shell I.D.: 1.37 RS-501	$19.99
	English 68 width RS500	$16.30
	English, 68 or 73 width MT 501	$20.99

		9 SPEED

		Cassete Cog
Chain Ring		11	13	15	17	19	21	24	28	34
	53	93	79	68	60	54	49	43	37	30
	39	68	58	50	44	40	36	31	27	22

% Chng sm to lg			11 🢥 13	13 🢥 15	15 🢥 17	17 🢥 19	19 🢥 21	21 🢥 24	24 🢥 28	28 🢥 34
% Chng sm to lg			18%	15%	13%	12%	11%	14%	17%	21%

Speed in MPH		11	13	15	17	19	21	24	28	34
	53	25	21	18	16	14	13	11	10	8
	39	18	16	13	12	11	10	8	7	6

The ave step between cogs in % using the formula (range^(1/number of steps) = 15.15%
Where range = big cog / small cog = 34/11 = 3.0909⋯
And Number of steps = number of gears - 1 = 9-1 = 8	Average	Max	Min	Std Dev
Percent change when shifting to a Smaller cog	13.12%	17.65%	9.52%	2.64%
Percent change when shifting to a Larger cog	15.20%	21.43%	10.53%	3.54%

		10 SPEED

		Cassete Cog
Chain Ring		11	12	14	16	18	20	22	25	28	32
	53	93	85	73	64	57	51	46	41	37	32
	39	68	63	54	47	42	38	34	30	27	24

% Chng sm to lg			11 🢥 12	12 🢥 14	14 🢥 16	16 🢥 18	18 🢥 20	20 🢥 22	22 🢥 25	25 🢥 28	28 🢥 32
% Chng sm to lg			9%	17%	14%	13%	11%	10%	14%	12%	14%

Speed MPH	53	25	23	20	17	15	14	12	11	10	9
Speed MPH	39	18	17	14	13	11	10	9	8	7	6

The ave step between cogs in % using the formula (range^(1/number of steps) = 12.60%
Change = ((larger Cog - Smaller Cog) / Larger)	Average	Max	Min	Std Dev
Percent change when shifting to a Smaller cog	11.17%	14.29%	8.33%	1.87%
Percent change when shifting to a Larger cog	12.62%	16.67%	9.09%	2.37%

The most important factor here is the maximum % change, and where it happens. By my experience, it falls about where I am when riding on mostly flat ground, with a moderately fast group, which is exactly were I Don't want it to be. A large difference. So moving from 9 to 10 sp