trek7.5fx

OK, I have a Trek 7.5 FX and my 9 speed Shimano Tiagra rear derailleur recently broke and it needs to be replaced.

My questions are:

• Can I upgrade to the 10 speed Shimano Tiagra (RD-4601), or should I buy off ebay the 9 speed Tiagra again (RD-4500)?
  They are near in price so I was hoping I could just do the 10 speed and not sure if differences matter in this case. Does anyone know?
• What cage size do I need? There are 3 rings so I am guessing medium or large. Also--what the hell is the GS version of these derailleurs?

Bonus Q's:
Any recommendation on chain? I was thinking just a modest priced KMC.
I have no idea how to figure out the size of my bike, does anyone know if there is a model number, measurement I can take, or quick pointer that will indicate size of my frame (13, 15, 17, 19)?

This image shows EXACTLY what my bike looks like, minus the broken derailleur.




Here are the specs, which can also be accessed here.
Frameset
Frame - FX Alpha Black Aluminum
Fork - Bontrager Satellite Plus, carbon
Sizes - 13, 15, 17, 19"
Wheels
Wheels - Bontrager SSR w/Clix
Tires - Bontrager Race Lite Hardcase, 700x32c; 60 tpi
Drivetrain
Shifters-Shimano Deore, 9 speed
Front derailleur- Shimano Deore
Rear derailleur - Shimano Tiagra
Crank - Shimano M443 Octalink 48/36/26
Cassette - SRAM PG950 11-26, 9 speed
Pedals - Alloy body w/alloy cage
Components
Saddle - Bontrager Select FIT Basic
Seatpost - Bontrager Sport
Handlebar - Bontrager Crowbar Sport, 25mm rise
Stem - Bontrager Select, 10 degree
Headset-Aheadset Slimstak w/semi-cartridge bearings, sealed
Brakeset-Avid SD-3 w/Tektro adjustable reach alloy levers
Accessories
Extras- Bontrager Satellite FIT grips


Any help appreciated!! Thank you.

bres dad

Does anyone know if a 105 RD-5501 is interchangeable with the Tiagra RD-4500?

cobba

Which models are you talking about ?

RD-5501-SS or RD-5501-GS ?

RD-4500-SS or RD-4500-GS ?

RD-5501: https://techdocs.shimano.com/media/te...9830603908.pdf
RD-4500: https://techdocs.shimano.com/media/te...9830607047.pdf

HillRider

Either model will work. The 5501/5503 are 9-speed versions but the 10-speed 4500 will also work. "GS" means a long cage and is the model you want for a triple crank.

You want any 9-speed KMC chain. In this case "9-speed" implies the correct width to match your cassette but a 10-speed width chain would also work. You don't want any chain listed as 7/8-speed as it would be too wide.

shelbyfv

You can use either the 9 or 10 speed. You need the GS version which is for triples. This is the "long" within the Tiagra group but is a "mid" in the larger scheme, with MTB derailleurs as the "long." KMC chains are good, I like the link. Any of them with 9 in the name.

trek7.5fx

Hi All,

Thanks for the response. bres dad, I tried responding to your PM but am unable to at under 50 posts apparently. Thanks for your consideration, appreciate the help!

I did a little research and it appears the 105 RD-5501 is actually cheaper on ebay than the older 9 speed I want (well, they are both old)--so I will buy that. if anyone can think of a better, cheaper alternative, let me know! I am also getting this KMC chain!

Any other tips and advice appreciated. Also--I assume my stock hanger will work with these derailleurs, can anyone confirm?

Thank you again.

HillRider

Yes it will. Rear derailleur hangers are universally threaded M10x1.0 and any Shimano, SRAM or Campagnolo rear derailleur will bolt right up.

leob1

The frame size should be on a sticker on the seat tube. Mine is.
Is the derailer broken, or is the hanger broken?

trek7.5fx

both broke, but i already ordered a new hanger a while back (expensive for a little piece of metal).

Purchased a 9 speed KMC chain today and the RD-5501-GS. Woot

alex jb

If you don't plan to update your cassette and shifter to 10 sp, I wouls stick with a 9 sp chain.
As others have said, the KMC chains are good and the quick links are easy to fit and re-usable, Shimano chains are mated and broken via a regular pin and a replacement pin, so you need a new one (pin) each time and if you don't get it just right you can have a stiff link in the future when you put the connecting pin.

trek7.5fx

I bought this bike over the summer, and it broke within 1 week. since then I haven't touched it. Thanks for all the insightful responses everyone, you are helping me get back on this bike and finally take initiative.

fietsbob

RD gets shoved sideways , between cogs, the number of cogs is the 'speeds'..

if you damaged the RD , you probably bent the hanger.

visit a Bike Shop, and they will re-align it.

trek7.5fx

thank you. i got a new hanger altogether. this should resolve it right? the actual bike metal doesn't usually bend, right?

fietsbob

NO.. there still needs an alignment tweaking , Shop tool is a $100+..

Index shifting is fussy about alignment.

service at the LBS will be much less than buying your own Shop tool

Dream On..