Road Bike, Cycling Forums banner
1 - 9 of 9 Posts

·
Registered
Joined
·
140 Posts
Discussion Starter · #1 ·
I just got a Trek 7500 hybrid and have some issues with the gearing. The bike came with a Deore 9 speed, a Shimano hybrid crank 26-36-46 and a 11-32 so it basically set up like a mountain bike. I want to set it up more like a road bike because I am going to ride it mostly on flats / rolling terrain and I don't need the range of gears. I switched the rear cassette to a 12-25 for starters but their is still way to much diffference between gears.

First question is can I take off the 36 chain ring and replace it with a 39? I know it's a 13 gear jump but I will rarely shift it down to the 26 chain ring.

I would consider switching the crank all together and replacing it with a road triple. No issues with the mountain bike front derailleur? My road bike has a 30-42-52 and a 12-23 and that works perfect for me. I was looking at some of Shimano's low end road cranks and I don't see any 30-42, everything is a 30-39.

Thanks
 

·
Registered
Joined
·
21,639 Posts
Working it out

VEN said:
I just got a Trek 7500 hybrid and have some issues with the gearing. The bike came with a Deore 9 speed, a Shimano hybrid crank 26-36-46 and a 11-32 so it basically set up like a mountain bike. I want to set it up more like a road bike because I am going to ride it mostly on flats / rolling terrain and I don't need the range of gears. I switched the rear cassette to a 12-25 for starters but their is still way to much diffference between gears.

First question is can I take off the 36 chain ring and replace it with a 39? I know it's a 13 gear jump but I will rarely shift it down to the 26 chain ring.

I would consider switching the crank all together and replacing it with a road triple. No issues with the mountain bike front derailleur? My road bike has a 30-42-52 and a 12-23 and that works perfect for me. I was looking at some of Shimano's low end road cranks and I don't see any 30-42, everything is a 30-39.
My suggestion would be to go to a narrower range cassette. For example, a 12-23 would give you a much tighter gearing pattern. I'm not going to take the time to sort out your gears for you, but I'm guessing that if you plot out the gears with your existing chainings and a narrow range cassette you'll get something you like. You can keep your current cassette for those trips to hill country.
 

·
Registered
Joined
·
1,846 Posts
You might not find a 39t in the bolt same bolt pattern, but you can use a 38t or 40t . I'd also consider going to a 11-21, or 12-23 cassette, unless you already shelled out for the 12-25.

I have my commuter set up similarly, using a step and half difference in the chainrings, plus a granny. This packs more gears in the most used upper mid-range, and leaves me the granny for when I need it. It's also a common arrangement for touring bikes paired with a wider cassette.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #4 ·
Putting on a 12-23 is a consideration and I actually have a spare to try. I would still like to get a chain ring. I know I can put a 38 on 40 would be perfect, I was just curious if the mountain bike derailleur will take the shift.
 

·
Registered
Joined
·
1,846 Posts
Yes, the FD will handle the shift, but as one who rides a similar combination, you probably won't be able to buy a matched middle and outer phased for hyperglide. Not a crisis, you can rotate the middle looking for the position which gives best shifting (doesn't help with a 40, since 40 divides by 5).

You'll get good clean shifting from middle and outer since the jump is small, going down to the granny will also be fine, but as you increase that gap, coming up from the granny won't be as crisp, but that's not a shift you expect to make often anyway.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #6 ·
I put the 12-23 on and I still have a problem. The bike goes pretty fast for a heavy bike and I would like to put on some 28 road tires because the hybrid tires really ride rough. The problem is when I am riding on the flats the rear is in the small cogs (14-13-12) and the shifts are rough. Could I remove the 46 and replace it with a 40 or 42? That would eliminate any issues with shifting and it put me right in the comfort zone as far as shifting. I never saw a 40 chain ring listed, were could I get one?
 

·
Registered
Joined
·
822 Posts
you've got 700x35 tires on their now, right? those theoretically will ride smoother than 28's, since they are wider & have more volume (more volume=more cushion).
Tried lowering the pressure?

As for rough shifting, that's a fairly simple adjustment (the shop you bought it should provide some free adjustments if you bought the bike there... if not see here). It may be as simple as turning the barrel adjuster on your rear derailler or shifter a click or two in either direction.

If you feel you really need a 40-42t front chainring, your LBS should be able to help you get one. I did find some 38-42t chainrings made by profile, FSA and others, but they appear to be designed for singlespeed applications, so don't have shift ramps/pins. You don't really need them to shift, but it makes shifting easier under load. I'd get a deore level 44t, good bang for the buck at ~$25.
 

·
Registered
Joined
·
14,713 Posts
I;m really confused here.

VEN said:
I put the 12-23 on and I still have a problem. The bike goes pretty fast for a heavy bike and I would like to put on some 28 road tires because the hybrid tires really ride rough. The problem is when I am riding on the flats the rear is in the small cogs (14-13-12) and the shifts are rough. Could I remove the 46 and replace it with a 40 or 42? That would eliminate any issues with shifting and it put me right in the comfort zone as far as shifting. I never saw a 40 chain ring listed, were could I get one?
Are you saying that you're cruising comfortably in the 36x13 or thereabouts on the flat, and you'd rather be in the middle of the cassette? If so, just shift onto the big 46 ring. 46x17 is almost exactly the same as 36x13. That should be a pretty comfortable cruising range, about 20 mph at 90 rpm.

If you're saying you have a problem in the 46x13, your proposed "solution" won't fix anything -- in fact, it'll just rob you of your high gears.

If you're super strong and you're cruising in the 46x13 (which will get you about 25 mph at 90 rpm), you should be on a road bike (and looking for a racing team ;-).

Maybe you're mashing at low cadence and need to spin more.

But tell me what gear you're really in when you're on the flats as you describe, and maybe we can be more helpful.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #9 ·
JCavilia said:
Are you saying that you're cruising comfortably in the 36x13 or thereabouts on the flat, and you'd rather be in the middle of the cassette? If so, just shift onto the big 46 ring. 46x17 is almost exactly the same as 36x13. That should be a pretty comfortable cruising range, about 20 mph at 90 rpm.
I bought the bike strictly for comfort. I have a road bike but a neck injury 10 years ago limits how many times I can ride it in one week. I am using this just to go out cruising so we are not giving it much of an effort. I am riding in the 36-13/14 on the flats; the problem is that nothing stays flat for a long distance. I tried riding in the large chain ring and if the terrain is totally flat it OK, but as soon as you hit an incline you have shift up pretty quick. I was just looking for a way to stay in the middle chain ring and still work the middle of the gears. It's OK the way it is, but if I can get a 39 or 40 chainring on it so much the better.

The bike has a Shimano crank, I would assume I could just switch it to a road crank and that would solve the problem.
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top