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Gearing thoughts

simonh0407simonh0407 Posts: 16
edited March 2017 in Workshop
Hello all, I'm recently returned to cycling, mid life need a hobby type stuff and can't understand why I gave it up all those years ago. :oops:
Teaching myself stuff has always been the way too, not unusually a little impartial information can be very helpful, hence this post.
My main involvement is off road but I do have an older though immaculate Bianchi via Nirone which I've just done my first sportive on.
Groupset is Ultegra 6600 with the exception of the front mech which I've changed for a 6700 (16 tooth capacity?) as the spring had gone a bit too tight making changing more difficult than I like, rear mech is short cage and the chain rings are standard 53/39 (110mm BCD) with 172.5 arms, 10 speed cassette is an 11-25.
Yes you are right, I'm having a little difficulty on the hilly stuff. :shock:
Cost is an issue or I would just swap the crankset for a mid compact so I'm thinking of tinkering.
It seems that the chain wrap for the rear mech is stated at 29 but people are suggesting that to be a conservative estimate of its capabilities?

Option 1 :- change the small chain ring to a 38t and the cassette to a 12 - 27 which puts it one over the stated 29 wrap limitation whilst bing inside the 16t front mech capacity.
(Except for short bursts turning the 53 11 combination is a bit over and above my legs capacity anyway so losing a little top end is acceptable.)

Option 2 :- chainrings are available in 37t too it seems though not OEM from what I can see so going 53/37 and sticking to 11-25 still gives me a total of 30 whilst taking the front mech to it's maximum 16t capacity.

I've done the internet based calculations and confused myself a little being honest so I'm looking for any personal experience if anyone is happy to share?

Will either change make a noticeable difference on the climbs?

Does Option 2 have any benefit over Option 1 other than cost?

Will either of them work without damaging the rear mech?

Many thanks in advance for your thoughts.

Posts

  • Congrats on getting back into cycling. If it's 6600 then the BCD for a standard 53/39 crank is 130, not 110 for that series as it's a 5 arm spider. I'm pretty sure the smallest ring you can fit is a 38T but I've not really looked. Cost-wise you're going to be dropping close to the cost of a new crankset for option 1 and I'm not sure option 2 is possible. Do you have a link to the chainring?

    Whether the difference is noticeable will depend. If you're stalling on the current set-up then you may find that, at first, it seems to make no difference and you still stall. If you are getting up things but it's a grind then yes, both would make a difference, how much will be dependent on you though.


    Personally, I'd be looking at picking up a crank with the new asymmetric 4-bolt pattern and compact rings (50/34). 34/25 should get you up basically anything but you can then fit an 11-28 if you want and drop the gear further. It also gives you the option of fitting semi-compact or standard rings in the future. The 105 5800 series crank can be had for a little over £80 at the moment.

    34/25 is pretty similar to 39/28 by the way, just a bit smaller, so just sticking an 11-28 out back could be an option (that's what I did).
  • svettysvetty Posts: 1,904
    edited March 2017
    Congrats on getting back into cycling. If it's 6600 then the BCD for a standard 53/39 crank is 130, not 110 for that series as it's a 5 arm spider. I'm pretty sure the smallest ring you can fit is a 38T but I've not really looked. Cost-wise you're going to be dropping close to the cost of a new crankset for option 1 and I'm not sure option 2 is possible. Do you have a link to the chainring?

    Whether the difference is noticeable will depend. If you're stalling on the current set-up then you may find that, at first, it seems to make no difference and you still stall. If you are getting up things but it's a grind then yes, both would make a difference, how much will be dependent on you though.


    Personally, I'd be looking at picking up a crank with the new asymmetric 4-bolt pattern and compact rings (50/34). 34/25 should get you up basically anything but you can then fit an 11-28 if you want and drop the gear further. It also gives you the option of fitting semi-compact or standard rings in the future. The 105 5800 series crank can be had for a little over £80 at the moment.

    34/25 is pretty similar to 39/28 by the way, just a bit smaller, so just sticking an 11-28 out back could be an option (that's what I did).
    ^This is pretty much spot-on. I would only add that losing weight and getting fitter is also a great help in climbing and the pleasure in scaling climbs with ease that previously had me grovelling gives considerable satisfaction so don't underestimate what you may be able to achieve over time :)

    Capacity is an issue for the rear mech, not the front and is a function of the difference in effective diameters of the relevant chain-wheels and sprockets (and thus the variation in effective chain-length taken up in accommodating this difference). From a practical point of view the 6600 short cage rear mech will in reality accommodate a 28 tooth largest sprocket on a 16 tooth difference chain-ring set-up e.g 50-34 (unless your bike has an unusual chain-stay length).
    FFS! Harden up and grow a pair :D
  • trailflowtrailflow Posts: 1,311
    Here's my suggestion. I dont think those changes would make a great deal of difference tbh. I think you'll still crave lower gears.

    I would try to buy a new or second hand compact 34/50t crankset off ebay/classifieds/retrobike forum.

    or find some crank arms only, then buy a Stronglight Dural 50t (or a 52t) chainring for £14, and a 34t inner for £10 from Spa cycles

    Try and put in a bid on these
    http://www.ebay.co.uk/itm/SHIMANO-ULTEG ... Sw2gxY1oyD

    Some crank arms for £40
    http://www.ebay.co.uk/itm/Shimano-TIAGR ... SwwpdW1u5K

    Full new Tiagra compact 34/50t crankset is £57
    http://www.wiggle.co.uk/shimano-tiagra- ... 60714206uk

    If you plan to do this, first check your FD can be lowered to the height needed for a compact. If your frame was designed for 39/53 it may not be possible.
  • trailflow wrote:
    If you plan to do this, first check your FD can be lowered to the height needed for a compact. If your frame was designed for 39/53 it may not be possible.
    Bianchi via Nirone is band on so should be fine.
  • simonh0407simonh0407 Posts: 16
    edited March 2017
    Hello guys and firstly, many thanks for your replies.
    My other new hobby is calling and time is tight so this initial response may be cut short before I'm finished thinking never mind typing, hope no one gets offended if that is the case.

    Hinaultscrapcousin you are correct, the BCD is indeed 130mm not 110 as previously stated. (I'm extra embarrassed given my profession but we'll say no more about that one to save my blushes. How I mis read the rule is beyond me.) The front mech is band on so you're spot on again.

    Trailflow, I've been looking at a compact crankset and have kind of agreed to buy one from a guy on an internet sales thingamajig but he is unreliable in terms of being able to reply to messages so goodness knows what might happen if I actually drive to buy this from him! I do now wonder if that might be a step too far and if semi compact ratios might be more suitable I guess. It's difficult to know without riding them for me is the point really. My riding is more about cadence than grinding it out I'd say, blame the old and skinny legs!

    My only reference point has been 'upping' the gearing on one of my mountain bikes but that was a while ago so without looking at the bike I can't quote the changes that were initially made. All I can say for now is that I ended up making further changes 'down' on the larger ring as it was too big a step up. Hence my caution this time really.

    Once again thank you guys.
  • 37t 110bcd on Fleabay, listing 272327830344
  • trailflowtrailflow Posts: 1,311
    SimonH0407 wrote:
    37t 110bcd on Fleabay, listing 272327830344

    Just checked the price of that. £36.95 !! quite expensive when you can pick up a 36t for around a tenner.
  • Yep, pretty hard on the pocket. Thankfully it is no longer an option given that it won't fit.
    DOH!
  • cooldadcooldad Posts: 32,599
    I just stuck an MTB cassette and mech I had lying around on mine. Cost zero and does the job.
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  • strathystrathy Posts: 13
    If you,re interested I have a complete Tiagra 4700 compact 170mm chainset (50-34) and bearings (68mm BB), taken off my Croix de fer. As new, taken off by my local bike shop.
    PM me , UK only, I,m in manchester.
  • tsarouxaztsarouxaz Posts: 70
    there is only one option and thankfully you are on 10sp. buy a low cost 50/34 crankset, and get a 10sp cassete of 11>34 and a semi low cost MTB 9SP rear deraileur like alivio or deore and you will be SUPERFINE for the british terrain!!
  • 34/34 is an insanely small gear for road riding! You'd be better off pushing!

    Simon, a lot of the very good racers I know ride compacts, if I were you that's the way I'd go. You lose half a gear pretty much (53/11 is 130", 53/12 is 119" and 50/11 is 122") and if you could push 53/11 on the flat or anything other than a long, steepish, downhill you wouldn't be struggling on climbs with 39/25 (unless we are taking several hundred metres at 15+%). To put it another way, at 90rpm, about the right cadence for general riding, you would be doing about 34mph on 53-11.

    I ride 53/39 11-28 on the West Coast of Scotland and I can be honest and say that I hardly ever need the 11 or even 12 tooth and I'm not a spinner as I ride a fixed wheel a lot. I ride it because I can and I don't want to fork out for a new crankset, but if you want lower gears it's the best option. A semi-compact would help maintain the high gear and does significantly lower the bottom gears, but a compact will lower them more and you're only really sacrificing a gear you probably never use anyway.

    Standards and semi-compacts make sense if you're a sprinter or a racer who needs the biggest gear that suits them for breaks etc. but for general group riding, sportives and so on a compact is more than enough.
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