Bicycle Mechanics - From 48/38/28 to 48/36/26

I have a Trek FX and I wanted to change the gearing from 48/38/28 to 48/36/26 and I was wondering if that's a job where I would need any special tools. Also if I do get into this can I use the BB on the Trek or should I get another BB to go with the Sugino. If I get a new BB what size would I need? I noticed on the Trek a crank with an allen head, and on the picture of the Sugino I see a square hole on the crank. I was also wondering how much I would gain by all this? As you can see I know nothing about bikes,but I'm trying to learn and I'd like to tackle this.With the crank I take off the Trek I was thinking I would put it on a 1979 Schwinn,if it fits.Any answers will be appreciated,thanks George

The change that you're proposing will only result in a gear that's about 1 1/2 gear/inches easier. That's not very much difference so, if it was my bike, I'd say it wasn't worth the effort.

Accurate answers to your other questions depend on missing information. Bottom bracket type and size, for example, depend on what the replacement crankset is. Necessary tools depend on exactly what you are doing and, to a degree, what your present equipment is.

The Sugino uses a standard tapered square (old-style Shimano) bottom bracket spindle.

I did exactly that on my 7300FX. I put a Bontrager crank on it though. Even then I had to switch the BB since the Bontrager uses ISIS and the old Nexave was square taper. I looked at the Sugino, but didn't go th at route because the BB that came on the FX wouldn't give the proper chainline with the Sugino. My FX is a 2005 model year, and maybe yours is different. You ought to chech what chainline you'll end up with.

The reason I swapped cranks is becasuse I didn't like the riveted steel chainrings on the Nexave crank. I wanted something with replacable chainrings.

The cheapest switch would be to buy a 26T granny ring (I assume its the standard 74 mm BCD) and just change it out for the 28T. A new crank or two replacement chainrings would be a sizable expense, particularly if you also need a new bottom bracket.

This will give you the lower low gear at minimal cost.

dck,I have a FX 7300 and mine is a 2005 model as well. What I'm trying to do is give me something to climb hills better. Where I live it's pretty flat, but when I go to the Texas hill country it gets pretty rough.I'm open for suggestions though,thanks George

Shiman XT and XTR (mtb) cranks are available in 46-34-24 and 44-32-22. Then, you can determine how low a gear you want by perhaps going to a tighter hub to, e.g., to about 25 or 27T. And, a new bottom bracket I think is less than $25. :)

The change that you're proposing will only result in a gear that's about 1 1/2 gear/inches easier. That's not very much difference so, if it was my bike, I'd say it wasn't worth the effort.

Accurate answers to your other questions depend on missing information. Bottom bracket type and size, for example, depend on what the replacement crankset is. Necessary tools depend on exactly what you are doing and, to a degree, what your present equipment is.


Agree 100%. I don't mean this as a slight to the OP, but people, you need to get comfortable with a gear chart, or the formula CR teeth/COG teethX27 gives you gear inches. We retro grouch's have gear inches committed to memory (alright, not really).

Its the only way to seriously look at gearing.

I would agree that it doesn't make economic sense to go to all that trouble for 2 teeth on the front chainring. Another problem I noticed is that 26 teeth up front is probably pushing the limit of the capacity of the Deore RD. A better way if you really want/need lower gears is to put a larger sprocket on the back. I haven't found a hill steep enough yet to need anything lower.