stevenpalomino

Hello everyone,

I'm looking to update my current setup to a compact setup but have no idea where to start. My current setup is a 52/36 crank with an 11/28 cassette ( Specialized 2015 Allez Comp Road Race Bike ). I'm looking to maybe update to a 50/34 crank with a 12/34(or 36?). What I'm not sure about is what I can/can't swap my components for.

Here's what I've got so far from what I understand:

Rear Derailleur - SHIMANO XT RD-M8000 REAR DERAILLEUR (Yes I know that's a mountain bike derailleur.. they're a bit cheaper than the road 11-speed ones.. from what I can tell..)

Cassette - SRAMŽ PG 1130 Cassette

Compact Crankset - Shimano 105 FC-5800 Compact Bicycle Chainset

Chain - SHIMANO CN-HG700 11-SPEED CHAIN

I'm open to thoughts or suggestions as I'm pretty new to cycling. Thanks in advance!

Tulok

I can promise you it won't make the bike be any faster or climb any better. I've done 5000ft of climbing over 80 miles with a low gear of 42/26 and i never wanted a lower gear. I definitely wished i had taller gears than 52/13 on the way down!

I noticed you you were looking at a wide ratio cassette with the compact, but really the crankset teeth # count has less effect than the (numerically) smaller cogs out back.

I think that a wide ratio cassette might be what you're really looking for. 11T up to 30 something. The jumps will be larger but your granny gear will be significantly easier for those extreme steep hills that are bound to come up.

10 Wheels

You may be quicker off the line, but your top speed will be slower.

stevenpalomino

Thanks for the reply Tulok

Would keeping my 11/28 cassette and switching to a 50/34 crank be the same as getting a wider cassette ratio and keeping the crank?

Maelochs

My first question would be, how high are the hills you climb?

Just joking, but really, a 34-36 is really low gearing. If you live in very hilly terrain and are just starting riding, that should help ... Otherwise, it would be expensive overkill.

Also, I think changing one or the other instead of both would be a better start. Possibly if you went to a 12-36 MTB cluster you wouldn’t need to swap up front and could save yourself a couple hundred.

The real reason to go to the MTB derailleur is that I don’t think a road derailleur would handle 34- or 36-tooth cogs. Make sure the derailleur works with the brifters, though ... some have different cable pulls for MTB and road.

If the MTB derailleur won’t work with the brifters, you can get a Shiftmate of a travel Agent pulley system.

I don’t think just dropping two teeth up front would make a huge difference in climbing ability. Probably there are others here who know better than I. i did some math and it seems like swapping the chainrings would make a very small difference compared to sapping the cassette.

By the way, depending on whether you have the SS or GS derailleur... the GS should handle 32 teeth I think. Much simpler if that works.

I assume you need a new chain to add a few links? Find the longest one you can,; maybe you can find one that’s long enough out of the box, and keep the current one as spare links/ a short emergency chain to get you to the bike store if the one on the bike breaks.

Anyway, if you can afford it and you want to do it ... the only real test is the real-world test. let us know how it works out.

stevenpalomino

I understand 10 Wheels..

I'm not looking to reach super high speeds or go pro or anything like that though.. how much top speed is really lost?

dedhed

Your 105 sti Shimano indexed road shifters won't shift that deraileur as it's 11 spd dynasys

stevenpalomino

That's what I'm realizing. I had just read about some setups. I don't do a lot of climbing, but have more climbing as a goal for 2016 so I want to make sure I can take longer / steeper climbs comfortably.
Really appreciate the reply. Lots of good advice.

Tulok

By dropping to a 50 from a 52 you lose a few % off the top. By going to a 32 from a 34, you only gain a few % worth of leverage. By going from a 28 top gear on your cassette to a 36 you gain nearly 25% leverage in your lowest 1-1 gear but you will keep the same top speed.

I think your stock derailer could possibly handle up to a 34. On the other hand, if you don't even use 1-1 now for climbing. Truthfully no gearing change is necessary at all and your current cranks and cassette may be perfect for your riding already.
11 speed stuff is not cheap so I would definitely ride what ya got until it's time for a new chain at least !

stevenpalomino

Perhaps something like this? Saw it installed here... although I'm not sure how "kosher" that is..

Tulok

That will work for your bike, but it might actually be the one you've got on it right now

just looked at the video. Good to see it will work on a 36T!

stevenpalomino

Good stuff here. the 36 front & 28 back combo is still a bit much on the longer & steeper climbs.. I'm wondering if maybe keeping the crank and switching to at least a 34 would fix things enough to where I don't lose any % on the top end and get a little relief for longer / steeper climbs?

Tulok

Thats what I would definitely recommend! If that derailer from CRC is indeed longer than your current one, all you need to do is buy that and a cassette that goes up to 34 or so and you'll gain a lot on the climbs

Maelochs

Well, that guy did it and it seems to work ... at least on the shop stand. If that's where you want to go, the trail has been blazed.

As for losing top speed ... can you spin your 52x11 at 110 rpm? In all likelihood you won't lose any top speed, though you will lose a small top speed potential. You will just have to spin faster in top gear.

Of course, on steep downhills you might be able to max out your 52x11---in which case, you were already sacrificing max velocity, but at that point you would be going like 38 mph, so why not tuck and coast anyway?

Tulok

very good point, that using 52/11 on the flats is probably not within the reach of mortals on solo rides.

stevenpalomino

Hmm.. just realized I've probably already got the medium mech.. It's definitely not short.. B screw is also not in much so it's definitely got room to be pushed down.
Looks like most common is either 11/32 or 11/36 though.. thoughts?

stevenpalomino

Good points. I'm not trying to go pro here so probably won't be spinning 110 on 52x11 or topping 38 on some descents.



Now I'm wondering if I should go with the 32 or 36.. 32 doesn't seem too far off from the 28.. and I'm not sure I want to put a 36 to the test and push the limits of my derailleur.. although I'm not opposed to it..

Tulok

The biggest problem if you over do it, would be going big-big and it stretches the chain flat and breaks your derailer off. Haha no big deal. 32 is 12% easier than 28 on the rear. If anything, I'd get the 36, then make triple sure I had a long enough chain before riding it. Though I doubt you'd ever cross chain that bad with 11 options on the tail end. It's a risk you need to decide on.

otherwise, you'd just need a few more links longer chain.

stevenpalomino

Yeah I think you're right. I currently rarely use big-big so.. just gotta make sure there's enough slack and clearance on the cog/jockey wheels

stevenpalomino

Something else I just noticed.. in the video I mentioned before.. he did have a compact 50/34 up front.. I know that gives a bit more slack.. don't know how much that affects derailleur placement?

Tulok

Shouldn't really change anything

stevenpalomino

Well.. turns out I've got the smaller cage.. I think it'll fit up to a 32.. wondering if I should go 11/32 and the 50/34?

stevenpalomino

So it looks like the options are getting a bit cassette (36) and change the derailleur to support it (Total about $86)
or use the smaller derailleur I have and update the cassette to the max it can support (32) and change out the crank to a 50/34 (Total about $142)
Not sure how much I gain by getting the 34 front with the 32 cog vs the 36 front with the 36 cog..
Seems like going with the 34 front / 32 cog would give me the most comfort?

catgita

The ideal chainring/cassette combination keeps you in the middle of your cassette for the majority of your riding, to minimize front shifts. Simply put, constant front shifts are a drag.

With a Shimano front shifter, you need to stick with the prescribed chainring sets, don't mix and match. The ramps and pins are designed to work only with specific timings between the teeth. Otherwise shifting may get pretty sluggish.

As always, choices vary widely by your situation. In my neck of the woods, climbs are steep and long, so pedaling down hill is a non issue. I am concerned mainly with the long periods of powering along, not a few short sprints at 45+mph that amount to nothing.

My personal combination in 46-30 and 12-32. I have never been dropped on a group ride due to that combo, but it is overkill on any sort of pavement.

Tulok

I'd go for the derailleur and cassette personally. It's cheaper and your crankset is already technically compact, so you could get smaller chain rings later if you needed an even lower gear. I'd probably leave it as is though. Save a hundred bucks and hit the hills, you won't need a tiny granny gear after the first couple of weeks.