52/36 crankset with short cage & 12-30 cassette

itchieritchie

Halp please!

I snapped the cage plate off my rear mech on my Trek Domane. Basically because I'm a very naughty cross-chaining bunny!

Current set up is compact (50/34) with a standard short cage Ultegra rear mech. On 10 speed.

In a bid to avoid the same in future, I'm changing my setup to the title.

Waiting for a Praxis Works mid-compact 52/36 crankset to arrive (heard good things). And ordered a new rear mech from CRC. That came today and it says I can run a max of 30t. But could I do this with a mid-compact or does it not matter?

I'm a mamil, though fairly fit, even if my racing days are well behind me (hence the sportive bike!), so looking at 12 - 28 or possibly 12 - 30 at the back. Could I get away with this?

I know Canyon bikes are often specced with 52/36. What do you run out back?

Suggestions / advice / insults all gratefully received.

stueys

I think the short cage is rated to 11-28 by shimano but most people say you can make an 11-30 work. Emphasis on think, I've not tried this out. The ratio up front shouldn't impact this, the thing to be wary of there is the gearing drop between big ring and small.

dj58

If the OP purchased the RD-6700-A SS, he can fit a 30T low sprocket.

964cup

The issue is total capacity (big front - small front + big rear - small rear) in your case 16+18 = 34. Theoretical max capacity of 6700SS is 33, so you should be alright although it will be marginal if you're running in the 36x12 (if it's not marginal, then your chain is too short, and it'll be too tight in the 52x30). By the same token you may be pushing the RD - the theoretical max is 28T on the cassette (hence the standard 11-28 max cassette giving total difference of 33 on both compact and pro-compact); as DJ58 points out the 6700A goes to 30T, but the capacity remains the same. Whether you use a compact or pro-compact is irrelevant, since the difference at the front is the same at 16T. I don't really understand why going pro-compact will stop you cross-chaining, I have to say.

Full data on your groupset here: http://bike.shimano.com/media/techdocs/ ... 671285.pdf

pilot_pete

Don't forget you will need a longer chain too...

PP

raisinberry777

itchieritchie wrote:

I snapped the cage plate off my rear mech on my Trek Domane. Basically because I'm a very naughty cross-chaining bunny!

All other issues in this thread aside, how could cross chaining snap off the cage plate of the rear mech? It wouldn't have an effect on the path that the chain travels through the rear derailleur.

Semantik

raisinberry777 wrote:

itchieritchie wrote:

I snapped the cage plate off my rear mech on my Trek Domane. Basically because I'm a very naughty cross-chaining bunny!

All other issues in this thread aside, how could cross chaining snap off the cage plate of the rear mech? It wouldn't have an effect on the path that the chain travels through the rear derailleur.

My thoughts too. Though I would wager his mech has hit the spokes because of a slightly bent mech hanger and/or badly adjusted low limit screw combined with some sudden out of the saddle climbing effort.

itchieritchie

Thank you for all your responses, really helpful as it seems I should probably opt for 11 - 28 to be safe, or 11 - 30 if willing to push it.

But I'm also now starting to feel a bit peeved. If what you say is true raisinberry777 and semantik, then the mishap may not have been my fault after all. It happened nowhere near a hill but on the Euston Road close to the Princess Grace hospital. I stopped so suddenly my rear wheel locked, which was bloody dangerous since a big red bus was breathing down my neck. The most you could say of that road traveling westbound is that it's a false flat. I'm 62kg, 5'8" so how much torque could I have been generating? And yes, when I dragged it onto the pavement, I actually had to bend the mech away from the spokes so I could wheel my bike home.

I'm not very technical so I had the Ultegra groupset fitted from another bike onto my Domane. All done at Cycle Republic, Euston Road. I was never quite happy with the job. They scratched my frame and the cabling is so tight that the brakes are hard to activate. Also lots of clicking when on 50 up front and 12 at the back, not sure if that indicates bad indexing adjustment in the first place.

Cheaper than Evans but then maybe now I know why. Anyway I vowed never to return to Cycle Republic but when I asked Evans about it they told me it was because I'd been cross-chaining and just put too much stress on the rear mech. It was they who recommended a mid-compact set up.

Oh god, could I have avoided all this by simply replacing the rear mech? Now even more confused...!!

Semantik

itchieritchie wrote:

Thank you for all your responses, really helpful as it seems I should probably opt for 11 - 28 to be safe, or 11 - 30 if willing to push it.

But I'm also now starting to feel a bit peeved. If what you say is true raisinberry777 and semantik, then the mishap may not have been my fault after all. It happened nowhere near a hill but on the Euston Road close to the Princess Grace hospital. I stopped so suddenly my rear wheel locked, which was bloody dangerous since a big red bus was breathing down my neck. The most you could say of that road traveling westbound is that it's a false flat. I'm 62kg, 5'8" so how much torque could I have been generating? And yes, when I dragged it onto the pavement, I actually had to bend the mech away from the spokes so I could wheel my bike home.

I'm not very technical so I had the Ultegra groupset fitted from another bike onto my Domane. All done at Cycle Republic, Euston Road. I was never quite happy with the job. They scratched my frame and the cabling is so tight that the brakes are hard to activate. Also lots of clicking when on 50 up front and 12 at the back, not sure if that indicates bad indexing adjustment in the first place.

Cheaper than Evans but then maybe now I know why. Anyway I vowed never to return to Cycle Republic but when I asked Evans about it they told me it was because I'd been cross-chaining and just put too much stress on the rear mech. It was they who recommended a mid-compact set up.

Oh god, could I have avoided all this by simply replacing the rear mech? Now even more confused...!!

Your gears clearly weren't adjusted correctly after they expertly fitted the new groupset- indexing, (cable tension) or limit screws incorrectly set and/or the rear mech hanger out of alignment-maybe the shop bent it when they scratched your frame? - they fitted another groupset to your bike and you were getting 'lots of clicking' in certain gears - clearly your rear mech has contacted the spokes- I fail to see how this could be caused purely by the fact of you cross chaining.
Some terrible mechanics out there . Earning a living from it too.

itchieritchie

Hi semantik, yes I think a picture is emerging now. A couple of things - firstly, that was a virtually new groupset they fitted so they should have had no excuses. Steering well clear of Cycle Republic from now on!

Second, I'm taking it to Evans this time. I'd rather support my LBS but not sure what they're like, really. And I don't want to take another chance!

But actually now I'm wondering if I did the right thing by ordering a new mid-compact chainset. It's not like I was running out of gears much, more that according to the impression I got from Evans, on 52t I'd be 'centreing' the chain line better for the same effort. Or did they get that wrong as well...??

Lastly - and most importantly of course - is the lesson that a bad gear job on your bike can leave you out of action for weeks AND hurt your wallet!

Semantik

itchieritchie wrote:

Hi semantik, yes I think a picture is emerging now. A couple of things - firstly, that was a virtually new groupset they fitted so they should have had no excuses. Steering well clear of Cycle Republic from now on!

Second, I'm taking it to Evans this time. I'd rather support my LBS but not sure what they're like, really. And I don't want to take another chance!

But actually now I'm wondering if I did the right thing by ordering a new mid-compact chainset. It's not like I was running out of gears much, more that according to the impression I got from Evans, on 52t I'd be 'centreing' the chain line better for the same effort. Or did they get that wrong as well...??

Lastly - and most importantly of course - is the lesson that a bad gear job on your bike can leave you out of action for weeks AND hurt your wallet!

The 52/36 chainset will work fine -though there was nothing much wrong with the 50-34 either. their analysis of a 52 chainring 'centreing the chainline better' is somewhat of a bizarre statement by them - it all depends what cassette is in there, what terrain you are on and what gears you like to push. there is nothing intrinsically better for your chainline about having the 52t chainring! What they probably meant was that you tend to spend a lot of time on the 50T ring but on the larger sprockets at the back -which is cross chaining territory- as using the 34 inner ring gives lower/easier gears than most of us typically want to use on the flat.

Just get them to check your chain is not too short for the bigger chainring and get them to check your rear mech hanger alignment too. If the old mech hit the spokes there is a chance it bent the hanger.even a tiny bit is enough to mess up your gears.

itchieritchie

Thank you everyone. It's so good to have impartial advice like this. I'll pop a mid-compact crankset on now and see if I can spend more time on the 36t ring. With the current 12 - 28 cassette, I think I'll just leave it at that.

And I'll definitely ask the mechanic to check the chain length...!!

Happy riding out there... :-)

svetty

itchieritchie wrote:

....And I'll definitely ask the mechanic to check the chain length...!!

Happy riding out there... :-)

It is the mech hanger condition and alignment that really needs checking out before they put a new mech on it.....

pilot_pete

Sorry, but I think you are wasting your money. All you need is;

1. Check the mech hanger for alignment. Straighten if possible or change for a new one if not. (£10-£20).
2. If your rear derailleur is serviceable fit it. If not, buy a replacement. £ depends on model you replace it with.
3. Get your gears correctly indexed and limit screws adjusted properly to prevent the rear mech from going into the spokes.
4. Check the rest of the drivetrain, such as the chain for damage (twisted link, excessive wear) and either use it if it is ok or replace. (Again £15-£30 depending on what chain you fit). Ensure you have the correct length chain (look at Shimano workshop guidance for measuring required chain length). Fit it if needs be.

Job done. Absolutely no need to fit a different chainset, even less so if you are on a tight budget. Oh, and find a mechanic who knows what the hell he is doing to sort out your brakes if your cabling is too short.

You have had a bad experience with Cycle Republic and now duff advice from Evans. Are you seriously going to spend money on a new chainset because the lad in Evans suggested it would stop you cross chaining? Find another, more reputable bike shop (you say you don't want to take the 'risk' on your LBS whilst seemingly happy to get some idiot in Evans sell you an unnecessary part that will not solve your problem!

PP

itchieritchie

Pilot Pete, I agree with you. I DON'T need a new chainset for this problem. I was, however, going to fit one anyway so figured I may as well include it with the service at Evans to save on costs.

The actual hanger looks fine, it's the cage plate that got caught in the spokes and is twisted. Chain is newish so excessive wear won't be the problem. I've bought a new rear derailleur because I'm not technical, as I've already mentioned, so don't really know what I'm doing to be honest. As I don't really know what went wrong in the first place (seems to have been incorrect gear indexing from what all of you are saying but just can't be certain!) I don't want to mess anything up! I'm sure, with a bit of time and patience, I could look at some Youtube vids and sort this myself but my tools are limited and I just want to get back on the road pronto. :-)

As for the indexing on the gears, the mechanic would sort this out of course. And I'll ask them to look at my cabling whilst we're about it.

You have a point about duff advice from Evans though. I told him that I'd source any parts myself and bring them in, so in all fairness, he wasn't at that point trying to sell me anything, but even so...bad advice it seems. I may have another look at my local LBS. Why not? Think I'll explain the history and give them fair warning that I'll expect a very through job. If I'm not assured, I'll look elsewhere.

On that last point, can anyone recommend solid mechanics in west/central London?

Thanks!

964cup

You can't tell if the hanger is bent by looking at it (unless it's not so much bent as b*ggered). Get it checked with an alignment tool. The most likely reasons for having ripped your mech off are:

1. Incorrect limit screw setting letting the mech overshift into the spokes.
2. Bent hanger, again moving the mech into the spokes when in the largest cog
3. Mech b-screw not set up correctly letting the upper pulley wheel interfere with the largest cog
4. Chain too long, letting the chain run against the cage when in small-small; this will also give you a very slack chain, which can slap, slip or jam.
5. Chain too short, running big-big, which can jam the chain and rip the mech off

All but 2 are errors by the mechanic; 2 should have been spotted by the mechanic (and you) because shift quality will have been poor and the chain noisy (since the mech wouldn't track properly parallel to the cogs).

dj58

itchieritchie wrote:

The actual hanger looks fine, it's the cage plate that got caught in the spokes and is twisted.

I would hazard a guess that if the gear hanger wasn't bent before your mishap, it will be now. I would change it as a matter of course. You can change it yourself and if you are going to fit a new RD you may as well fit a new hanger.

I known you said you are not technical and don't know what you are doing, but now would be a good time to learn how to do these jobs yourself, it really is not that difficult once you understand what the high, low and the B-tension adjustment screws do and how to adjust the cable tension to index the gears. There are some good youtube videos that show how to fit, set up and adjust a rear derailleur. Shimano online PDF files are a good reference source if you don't already possess hard copies.

If you post questions in the Workshop forum there are experienced and knowledgeable members who can advise you on all aspects of bike maintenance.

itchieritchie

Wow, loads of info here. You guys are GOOD...!!

Ok, I guess it IS high time I started doing these jobs myself. Challenge accepted. Will take me longer to get on the road but I can console myself with the fact that I'm saving on outrageous mechanic's fees. Plus, I have always wanted to get to know my bike more *cough* intimately...

YouTube vids, PDF's and workshop forum it is then. Until now, the most technical thing I've done is change brake shoes and swap out a cassette. Got a small Ice Toolz set but if I need anything else, I'll build up slowly.

As a starting point then, can I just get any old (but new) rear hanger or is it bike/RD specific?

dj58

The gear hanger will be specific to your bike make and model, you could see if Evans have it in stock, you need to identify the shape and method of fixing to your frame. You may be able to identify it on this website, don't worry about it being MTB, they also do road bike hangers.
http://www.mountainbikecomponents.co.uk/hangers/

Couple of vids for you to peruse.

https://www.youtube.com/watch?annotatio ... PLiW-0zLa4

https://www.youtube.com/watch?v=Bbk5RcH ... pRqM4dtlDC

bikingeveryday

Some bikes can run a 30 rear cassette with a short derailleur if the hanger is long enough. Besides chain wrap it is important for the derailleur top pulley to clear the gears teeth. This is what the "B" screw is for. Not all "B" screws will give the proper clearance. Sometimes a longer (4mm X 10 or 12mm) screw will work or turning the screw upside down (so the screw head effectively increases the length) Some hangers do not have enough surface where the "B" screw lands causing the screw to slide off the hanger and not increase the clearance. The limit screw may not have caused the derailleur to contact the spokes it may have been caused by the jockey pulley jamming into the cassette teeth.

W12_Lad

I haven't read all the posts so sorry if already said.
I have 52/36 and 12-30 (old 105 10 speed) on one of my bikes and have had no problems at all in 2000 odd miles.
Another 6000 miles before, i was running 50/36 12-30 also with no problems.