The Official DMF Bicycle Thread

[triangleforge]

It does sound like a calibration issue -- different tires can change the actual circumference of your wheel by a few percentage points. To be accurate, you've got to do a roll-out measurement of the wheel & input that info into the computer set-up; most bike computers have instructions that'll talk you through it, and virtually no bike shop I know of is going to bother to go through the process unless you specifically ask them to AND are willing to pay for it.  

If you really want a head-to-head comparison, you'll need to ride the same courses a couple of times on each bike in similar conditions, paying attention only to the elapsed time. You can also borrow a friend's running or biking GPS unit and use it with both bikes so that you're taking possible differences in wheel circumference out of the equation.

The other issue with a new bike is that your position's probably changed just a bit and it'll take your body a while to adapt. If your'e faster on the flat but a 7 lb. lighter bike feels like it's climbing slower, I'm going to guess the Felt is a more aggressive & aerodynamic riding position and your body's not used to it yet.

[fastwin]

20 points to triangleforge's team. You succinctly said what my ramblings wanted to say!

[Randimus Maximus]

Another thing to keep in mind is that on your old bike you had a 39 tooth small crank ring, vs. the 34 on the Felt.  Not sure which chainring you're riding in on the slower speeds, but that gearing change will definitely have an impact.

[cokey]

http://www.giant-bicycles.com/en-us/bikes/model/seek/7342/44056/

Any insight on this model?  I may get it soon..

[Monster Dave]

Thanks guys for all of your input. I really love my new bike and just want to fly on it!! I think there are 2 things that need to be addressed - gearing and wheels. I checked my computer and it's setup correctly so there's not a calibration issue.

Randy (or anyone), can the front gearing be changed as easily as the rear cassette?

Wheels are easy to test since I have my others to try for comparison - one set should be better than the other either way.  

[sbrguy]

the gearing on the front is actually easier to change than the gearing on the back.

but i would personally keep the 53/39 up front,what is the current cassett on the bike?

remember 3 teeth up front is almost the same as going one gear down on the back so if you want to simulate the same thign as your old bike you have to just shift to one bigger cog up in the back than you did on the older bike, i think that is the slow feeling you are feeling.

your new bike is going to be faster than the old one, mayb ethe feeling of it feeling sluggish is the geometry of the bike basically remember you probably got a more race oriented bike so it may in some ways feel different than the older bike.

[Randimus Maximus]

the gearing on the front is actually easier to change than the gearing on the back.

but i would personally keep the 53/39 up front,what is the current cassett on the bike?

remember 3 teeth up front is almost the same as going one gear down on the back so if you want to simulate the same thign as your old bike you have to just shift to one bigger cog up in the back than you did on the older bike, i think that is the slow feeling you are feeling.

your new bike is going to be faster than the old one, mayb ethe feeling of it feeling sluggish is the geometry of the bike basically remember you probably got a more race oriented bike so it may in some ways feel different than the older bike.

His old bike was geared at 50/39.  The new bike is 50/34. Hence my earlier comment about chainrings. 

Add to tag along on triangleforge's comment about body positioning and such, did you get a full "fit" when you picked up the bike?  And by full fit, I mean where you rode the bike on a trainer, they measured body angles, checked for knee alignment with a laser & such?

[Monster Dave]

the gearing on the front is actually easier to change than the gearing on the back.

but i would personally keep the 53/39 up front,what is the current cassett on the bike?

remember 3 teeth up front is almost the same as going one gear down on the back so if you want to simulate the same thign as your old bike you have to just shift to one bigger cog up in the back than you did on the older bike, i think that is the slow feeling you are feeling.

your new bike is going to be faster than the old one, mayb ethe feeling of it feeling sluggish is the geometry of the bike basically remember you probably got a more race oriented bike so it may in some ways feel different than the older bike.

The setup difference is:

GT-R 50/34 crankset
F5 53/39 compact crankset.

GT-R came with a 12/25 cassette that I swapped out for a 12/26.
The F5 came with a 11-25 cassette.

Yes, I did get a full on fit, measurements and all when I bought the F5.

This crap really confuses me. I reverified the crankset sizes and rear cassettes, and the F5 has a larger crankset and smaller rear cassette while the GT-R has a smaller front and bigger rear....so were is the performance difference?

What would be the performance change if I put a 12/26 (for example) on the rear of the F5 with it having a larger front crankset??

[Randimus Maximus]

Wait.

I'm confused now.

In your earlier posts you states that the GT had a crank with 50/39 gearing.

And then you said when you picked up the F5 you were relieved to find out that it had a compact crank, which would be geared at 50/34.

Now you say it has a compact crank, but geared at 53/39, which would be a standard crank.

[Monster Dave]

Wait.

I'm confused now.

In your earlier posts you states that the GT had a crank with 50/39 gearing.

And then you said when you picked up the F5 you were relieved to find out that it had a compact crank, which would be geared at 50/34.

Now you say it has a compact crank, but geared at 53/39, which would be a standard crank.

  ahhhhhhhhhhhh!!! Sorry - when I rechecked the specs I went to the mfg site and got them off of there. and then got mixed up!! It DOES have a compact crank, which I didn't realize that would be geared different....

So the specs then are:

GT-R  50/39 crankset
F5 50/34 compact crankset.

GT-R came with a 12/25 cassette that I swapped out for a 12/26.
The F5 came with a 11-25 cassette.


Sorry!

In doing my homework on this, here's what I'm looking at:

Currently:

Shimano 105 11/25 : 11-12-13-14-15-17-19-21-23-25
-Up to either :
SRAM           12/25: 12-13-14-15-16-17-19-21-23-25
SRAM           12/27: 12-13-14-15-16-17-19-21-24-27


-Is there any reason to lean more towards the 25t than the 27t cassette?

*edit - so over lunch today I was reading (a lot) about gear ratios etc and found one article that said that the 50/34 crank along with the 11/25 cassette is comparable to the 8/9 speed bikes with the 50/39 crank and 12/25 cassette. Is that true?
If that's the case then gearing is not the issue...that's it...after work, I'm going out for a 'balls to the wall' ride....

[bryant8]

Dave, don't over-think it.  Get adjusted to the new bike then start fooling with GR. It could just be a matter of you focusing more on the bike than your spin. I'll admit when I got my new 4.5 Madone I was messing around with features on it instead of spinning with focus.

Or use the pace difference as a motivator to justify the purchase and crush your PR

[sbrguy]

which ring ar you using more the small or large chainring? with your current setup the 50 should feel identical to the old bike when you both have them in the 50  and the same sprocket size on the bakc, the small chain ring is tha tpart that will feel different.

[Monster Dave]

which ring ar you using more the small or large chainring? with your current setup the 50 should feel identical to the old bike when you both have them in the 50  and the same sprocket size on the bakc, the small chain ring is tha tpart that will feel different.

So I did gave this morning's ride my best effort and have come to realize that I REALLY need to change the gearing. As it stands, the gearing is so tall that the time that I do spend on the big cog is either on downhill runs or total flats, but any and I mean ANY climbing, I have to drop down to the small cog.

That being said, in order to even achieve an average speed of 18.2mph this morning (still less than my normal), I had to spend nearly 90% of the time on the small cog and in the middle to outer gears of the rear cassette. It's just geared too tall for the rolling terrain here. I'm a strong climber too and this setup is as the French say "Le suck".  

[fastwin]

If your biggest complaint is a simple chainring or cassette change then you are in good shape. No biggie.

[Monster Dave]

If your biggest complaint is a simple chainring or cassette change then you are in good shape. No biggie.

No biggie if I didn't have a race in 3.5 weeks and still need to get this new bike dialed in correctly.

I'm going to try and get my bike into the shop because when I spoke with someone there, they told me that the gear ratios should be really similar to my previous setup on my GT-R and that something else could be causing the 'drag' that I'm feeling.

Really, I think the hardest part is really pinpointing the precise problem...and I think I'm starting to frustrate the guy at the bike shop....