Chain rings and shifters
Hi all, I am ordering a Surly LHT, 54cm, 26" this week. But I am trying to spec out the drivetrain. I had decided on an XT 48-36-26 up front but, have decided that I would be happier with a big chain ring of 52. I also want that granny gear 26 also. SO this has created an issue. I am looking at XTR in the back, and my concern is the big gap in chainrings. Any help on this will be appreciated, opinions are welcome. The ride will be used for commuting and small tours primarily for 7 months and then I will retire and do what everybody here wants to do.
Sell it all and live off the bike!!! I'm stoked
Older than dirt
11-32 or 11-34 on the back. For loaded touring you're pushing a lot of gear if you go up to 52 in the front. I run 48/38/28 with an 11-32 and it's all the gear I could need.
Thank you and Sorry left that out 11-34 in back. I spend a lot of time in the 52 on my road bike and also the 46 I have on my mountain. Granted I am not loaded at that time either, so?? I'll have to sleep on it. Is it possible to get a crank that I can swap chainrings up to 52...in the XT group. Also, I want to utilize indexed shifters on the downtube, anybody done that on the LHT.
Older than dirt
I'm not saying they're not out there, but biggest I found in Shimano MTB cranksets was 48t. I haven't perused the FSA offerings, that's certainly an option.
I opted away from the 11-34 because I didn't like the 26/30/34 jump in the lower gears. the 11-32 is pretty linear across the range. I figured that if the 32 wasn't deep enough I'd drop the small chainring a couple of teeth and keep the linear range but just drop gear inches.
As to the downtube shifters, have you looked at the 7600/7700 Dura-Ace ones? Out of the box I know they need braze-ons, but I see no reason you couldn't fab a clamp if you were a bit handy. I'm a brifters fan personally.
Just stick with the stock XT rings for awhile. Maybe the 48X11 is a high enough top gear for you. If not, you can change the crankset to something else.
If you're going to use STI brifters, I'd stick to with stock Shinamo triple chainring combo of gaps of 12 (big to middle) and 10 (middle to granny). Yes, you might be able to make something else work, but it can be tricky.
If you have friction shifting for your front derailer, it's easier to use different combos of chainrings.
The LHT frame has downtube shifter bosses. No need for clamps.
Originally Posted by CCrew
What crank model do you have on the front that gives you the 48 big ring?
Originally Posted by CCrew
I am not sure it is as difficult as you seem to imply. I have summarised some suggestions made elsewhere and also linked to pages on this topic. Details here.
Originally Posted by tacomee
Yes, I know non- stock Shimano spec'ed triples can work with STI brifters, but why? Shinamo is has designed all the parts for a 12 tooth drop fallowed by a 10 tooth drop, with ramps and pins. Yes, I know that Tiagra and Sora front derailers are a better bet to work with a non-standard drivetrain. But this stuff isn't easy to do, and it's also possible to get parts that absolutely aren't going to work together. The only crankset without the 12/10 tooth drops I'd suggest is the Sugino triples with the classic 10/10 drops. Becuase they are so well ramped and pinned, they work with almost any Shimano road derailer (PM if you really wish to know the ones that won't work-- I've been defeated before)
Bike shops run into questions like this all the time and suggest staying away from potental pitfalls-- home wrenches (many who as good as shop wrenches, BTW) often disreguard professional advice and get things to work anyway. And sometimes they end up buying different parts and starting over.
So if you're running custom chainrings and STI brifters, you're above average at wrenching. Gold Star! even.
Sorry to get so far off topic. To the OP.
Get a standard, good quality road triple. A used one that takes a square taper BB isn't a bad idea.
Trade out the granny gear to smaller one.
Get a *Third Eye* chain catcher to prevent dropping the chain off the granny gear.
This should do it.
If you WERE to find a workable method of shifting the front from 26 to 52 and using an 11-34 cassette, I would think you`d run out of takeup room on the RD. I don`t know this for a fact, but it seems like another concern to me and it hasn`t been mentioned yet. Maybe you need two bikes?
I think that would just be a matter of way reducing the tolerance for cross-chaining. Where big/big might ordinarily give chain rub, in that 52/11-34 setup big/big (or even 52/large *half* of cassette) might simply not work at all.
Originally Posted by rodar y rodar
48/11 is bigger than 52/12 so I'd be surprised if it's not enough gearing for most non-time-trial uses. I accidentally got shipped a 12/34 rather than 11/34 and I do somewhat notice the difference between 48/11 that I used to have and 48/12 but a) not often or for long and b) not enough to do anything about it.
Then again, that kind of inertia I have is the exact argument for starting w/ what you want rather than seeing how well you can live w/ something suboptimal. Suboptimal alone can be pretty easy to live with, but then it's... suboptimal.
ps-> I did rejigger a 105 52/42/30 crankset to 52/38/26 and it destroyed the indexing but worked fine friction. Wide-ish road cassette, 12/28 if I remember correctly, road derailer.
Last edited by HardyWeinberg; 01-04-09 at 09:17 AM.
I'd like to recommend a 24-tooth chainring for your granny, and 22 would probably be better. (My Sugino crank won't adccept smaller than 24 or I'd probably have a 22.) When you're humping a big load over a long mountain pass, you'll thank me.
No worries on the off topic, all information is welcomed and education is always a plus, on any subject. Thanks to all for the outstanding input. Tacomee's quote sounds like the best option, and will allow good quality components, work effectively, and shouldnt be too labor intensive. This will be the route I take, so I am off to ebay to look for road triples....105 should get the job done. Thanks again.
Originally Posted by tacomee
Option #2 for me is to keep a spare crank set up that will apply to the terrain, when it traversing the Rockies go down to the 22. But for most other riding hang with the 26...any thoughts here. Oh and of course I would change all that prior to leaving home on a tour.....just a thought...or is this to complicated of an idea?
Originally Posted by BigBlueToe
Just to summarize what I have done on a Soma DoubleCross:
Ultegra 9s triple components:
XT 9s components:
- Crankset 22/32/48
- Cassette 11-34
Note that the crankset came with 22/32/44, but the FD cage was so long that it would hit the chainstay while the cage was still 3/8" above the 44 ring. So I swapped out the 44 with the 48 from a "trekking" set of chainrings I had on hand, which enabled me to properly position FD cage to the 48. It *would* shift with the 44, but it works better with the 48.
The adjustment is very critical on the FD for the 22->32 shift. It must be set so the first full sweep of the shifter just barely gets it onto the 32. If the cable gets a bit loose, the 22->32 shift must be done as follows: 22->48->32. That works until I get the cable re-adjusted.
This combination exceeds the wrap specs for the RD. On the small/small combo, the lower chain is just 1/4" from touching the upper pulley. I am able to shift into every combination w/o chain problems, but when in:
- 48 + two largest cogs
- 22 + two smallest cogs
there is lots of rubbing on FD cage which cannot be adjusted out, so you really don't want to run these combinations.
In summary, I am very happy with this setup. I encounter 12% grades even on my shortest training rides around here, and up to 19% on longer rides. I built this bike for one-day tours of up to 120 miles and 10,000' climbing with minimal baggage.
Nice ride "Shim"
That sounds like a very sweet set-up. I am so stuck on the fence. As previously mentioned I will probably stick with the same that you have. The possibilities are endless if need be. I guess most importantly is to just ride. I wish I had mountains...here in the Florida panhandle they are non-existent, another reason to tour away from here...LOL. Thanks for the input.