Help Me out Here Guys Please

[Edge705]

Ive just converted my Scott to a compact chainset I went for 50/34 Front 11/28 Rear previous it was 53/39 12/25 so Ive changed both the chaionset and the rear cassete. (see pictures attched)

I took a link out of the chain as instructed I think I need a bigger rear mech medium istead of the current short but before I take the plunge I need to know what I got wrong here

Now I know its not practical to have the chainline big at front big at back and small at front small at back but even so surely the chain should not be stretched like it is

I think its the 28 tooth causing the issue at the rear but like my friend pointed out I had 53/25 before and I have the same in 50/28 so I should have been ok

Thanks in advance

 

[PpPete]

Yes you need a medium cage mech - and to put back in the chain link you took out. I don't know who "instructed" you take a link out but they were clearly wrong.

 

[smithy92]

Longer chain by the looks of it. No matter which length mech you put on the chain is still going to be short.

 

[smokeysmoo]

+1 for longer chain. DO NOT refit any chain links by pushing the original pins back in on a 10 speed. I learnt this earlier this week .

You need to either use a missing link(s) like THIS/THESE, or special Shimano pins available HERE

 

[Edge705]

Ok Guys thats great I dont mind buying a new chain but should I buy a new mech while Im at it? will a new mech make that much of a difference I mean the medium mech?

 

[gds58]

I think that you definitely need at least one more link in the chain, possibly even two, and if you put two links back in then a medium length cage will work better and give smoother changes. At the moment the chain is way too tight.

 

[PpPete]

Ok Guys thats great I dont mind buying a new chain but should I buy a new mech while Im at it? will a new mech make that much of a difference I mean the medium mech?

If you read the Shimano technical documents the 6500 and 6600 short cage mechs are not rated to cover the range you have, either on the front or overall. The medium cage ones would have no trouble. Just noticed however that the rated capacity has increased on the latest series. The 6700 short cage should be OK - but right on the rated limit.

I'm assuming you are sticking with Ultegra - not checked the other offerings.

 

[Edge705]

Thats Brill Guys the rear ultegra mech (medium) is on offer at Ribble I'll buy that and a new 10sp chain and give it another go.

Many Many thanks for all your replies

 

[RecordAceFromNew]

You shouldn't have been adviced to reduce the number of links. 53/25 requires the same number of links as 50/28. Further since you are not running a half link chain you can only add or remove an even number of links at the same time, so you must have removed two links not one. If in doubt about how long a chain you need why not use a calculator?

Current Shimano Ultegra 6700 short cage has a wrap capacity of 33T, which is what you have (50-34+28-11). However I am unsure if yours is a 6700, and Shimano have been making different versions of Ultegra for years. But in any case there is a good chance yours is ok since offical wrap range is usually conservative anyway.

A possible though again unlikely problem you might encounter is the top jockey not clearing the 28T sprocket, if so adjusting the B screw will most likely make it work just fine.

 

[RecordAceFromNew]

As PpPete said indeed earlier versions of Ultegra don't have the same wrap capacity, so what you have can e.g. be exceeding official range by 4T. There is a chance that it works, and the chance will be improved by using a chain that is not longer than necessary, but it will be impossible to be sure without trying.

 

[Edge705]

OK Some great advice Ive ordered the medium rear mech and new chain I stated this project to convert my occasional Sunday steed to a more flexible option for attacking the the big mountains in europe next year. I had contemplated buying a new bike but given the cost and how much it would get used there seems litlle jsutification.

If I can get this combination working well I will be more than pleased

Cheers