Trying to identify 105 groupset

[surfguy13]

Trying to determine what series the 105 groupset is on my bike. It is a mid 90s Vitus I believe (although not 100% certain) and was told that the groupset is original to the bike. Not sure whether this will help but this is a photo of the rear mech:

 

[mdvineng]

There's usually cast in version numbers on the reverse of the mech.
Looks like 105sc series. Check on velobase.

 

[jim haseltine]

Yeah, possibly a 105SC. Problem with Shimano around the early-mid 1990s is that there were a number of supersessions in the 105 range so exact model id from a picture isn't easy.

 

[foz]

The model number will be stamped on the rear parallelogram plate

 

[surfguy13]

Brilliant, many thanks for the info!! Appreciate it. Will check the rear of the mech.

 

[otherself]

That's a RD-1056 rear mech from the 8-speed 1056 groupset (1993)

 

[surfguy13]

Many thanks @otherself. Really incredibly helpful to see the different versions. Looking at the velobase webpage I was fairly convinced that mine group was the RD1056 as it is an 8 speed group. However, it's interesting to see that my STI brakes/shifters are 1055, brakes are 1055, hubs are 1056 as is the front/rear mech.

To be honest I was asking the question in case there was any difference between the different versions of the rear mech. The group on this bike has a 13-26 cassette and as I am looking to install a new one, I wasn't sure if the rear mech would stretch to a 12 or 13-28. I can get a 12-25 I think which would definitely work fine and be more or less like for like. Maybe that's the best option as a 13-26 cassette seems to be hard to find.

Thanks again!!

 

[sjcprojects]

This mech will work with a 28T cassette fine, if you do want to go down that route. I've used that set up for years with no issues. That whole 105 series is great in my experience.

 

[surfguy13]

Aha, brilliant, really great to know that. Yes, agree totally, this is my first 105 group old or new and I'm very impressed. Just changed from a DA 7401 group that I've been using for many years and although the 105 maybe feels a little bit plasticy compared to the 7401, changing is probably just as good. I was also using a 12-21 cassette with the DA and the 13-26 definitely suits these old legs better!!!

 

[pigman]

Many thanks @otherself. Really incredibly helpful to see the different versions. Looking at the velobase webpage I was fairly convinced that mine group was the RD1056 as it is an 8 speed group. However, it's interesting to see that my STI brakes/shifters are 1055, brakes are 1055, hubs are 1056 as is the front/rear mech.

To be honest I was asking the question in case there was any difference between the different versions of the rear mech. The group on this bike has a 13-26 cassette and as I am looking to install a new one, I wasn't sure if the rear mech would stretch to a 12 or 13-28. I can get a 12-25 I think which would definitely work fine and be more or less like for like. Maybe that's the best option as a 13-26 cassette seems to be hard to find.

Thanks again!!

Probably works up to a 30T cassette. Most of the traditional Shimano pattern ones do