Bicycle Mechanics - Shimano Altus vs Shimano asis (or a515)?

I just had a question about these two shimano derailleurs. My hubby's Trek 4500 has a Shimano Altus/Alivio rear derailleur, and I've got a new Trek 4500 2001, too (woohoo!) , but its rear derailleur is a Shimano asis (or a515--it's silver). Is there a difference between the two?

My LBS says that the 4500s were equiped with Altus derailleurs towards the end of their production, and the asis (or a515) were during the earlier round. Is it also because I have the smaller frame (13")? There's so many different derailleurs out there, and I couldn't find any info on Shimano's site about the older model.

Any help would really be appreciated! :D

Not sure if this helps, but I've never heard of the asis (or a515). I suspect it's equivalent to the Alivio. Shimano is notorious (sp?) for changing names for their different level of parts. For example, Fubar has DX components on his Gary Fisher. The DX line later changed to LX, who knows why. Shimano used the Deore label a while back, then it seemed to go away, now it seems to be back again. Their marketing people must not have much work to do except change the names of component lines. And don't get me started on the addition of gears every 2 years :irritated The difference in your components has nothing to with the frame size though. It probably has more to do with the production run of your bike and what was speced at the time.

thanks, riderx! That makes me feel a lot better. Our marketing department (well, at my last job) well, at least some of them, were quite busy making up complicated names, instead of realistic and unobtrusive names. ;) Kinda reminds of me of the whole "new Coke" fiasco. :D

Anyway, I have yet to take my new bike out for a spin today, so with all those new parts, I'll be off tomorrow taking up some mileage! :D

Hi Techno! Congratulations on both your's and your husband's new bikes.

I checked out Shimano's website and found out some info on their derailleurs.

The order from top of the line to their more recreational components are as follows:

1. XTR
2. Deore XT
3. Deore LX
4. DX
5. Deore
6. Alivio
7. Acera
8. Altus
9. Tourney

The difference between numbers 6, 7, and 8, according to Shimano are:

Altus is a 7-speed MTB-style component group for city-sport and youth bikes. Altus provides a feeling of comfortable control that inspires confidence, especially among novice cyclists and younger riders.


Acera is an MTB-style component group that offers 8-speed drive train components. Acera delivers the responsive feeling of a real mountain bike to casual riders and entry level cyclists.


Alivio delivers a great combination of style, value, and responsive performance. New Rapidfire shift lever sets and front and rear derailleurs have a more streamlined up-scale look. Eight-speed drivetrain and a full compliment of advanced Shimano functions make Alivio the trend-setting group for quality recreational mountain bikes.


I hope this helps Techno! :)

Marcy, thanks for the details and marketing from Shimano.

I don't know.... can you really believe all that stuff?

"Altus provides a feeling of comfortable control that inspires confidence, especially among novice cyclists and younger riders."

Really? Inspiring confidence through a derailure. Hmm.

"Acera delivers the responsive feeling of a real mountain bike to casual riders and entry level cyclists"

Really? Responsive feeling of a real (not fake?) mountain bike (not a rode bike). Gosh. Hmm.

Here is a layman's quickie explaination of derailures

The really critical thing about derailures is the freewheel width they are designed for and the sprocket size range they are designed to work with.

What that means in simple terms is that the rear derailure has two major things it has to do:

1) Move the chain sideways. Thus, the derailure has to be designed with enough sideways movement for the whole freewheel. Thus, some derailures might work on a 7 sprocket freewheel, but not on a nine sprocket freewheel.

2) Take up chain slack: The derailure keeps the chain taunt. The greater the gear ratio range, the more slack the derailure has to take up. That's why you will notice that mountain bikes have longer chain takeup levers than road bikes (the chain take-up lever is the doo-hickey with the two little wheels attached that the chain wraps around). Mountain bikes typically have a wider range of gear ratios because of the uphill loads that require more significant downshifting than roadbikes.

The rest is springs, materials, and placement design. Most derailures work on basically the same concept of spring generated tension to move the derailure into position.

There is certainly a difference in derailure qualities. Most of the difference is noticed in longevity of the derailure and reliability. You might also notice a difference in response between derailures.

However, if you are a young novice cyclist looking for "inspired confidence", a bicycle derailure may not be able to do that for you.