10-speed: can I change double to triple?

mrjimmartin
Posts: 9
Hi all,
I've just discovered this excellent forum, and am glad there's a 'proper' place to go with UK specific advice.
Getting to the point, I'm about to ride the C2C, and am worried that my road bike's gearing is too high. It's a Giant OCR1 and I've had it for about 5-6 years. Covered loads of miles, but mainly commuting.
I now realise the C2C's mountains are going to mean the gearing is too high to pedal with sensible cadence. What are my options on a limited budget?
Here's what I know: the Shimano 105 Flight Deck shifter has three positions, so I should be able to upgrade to a triple. However, the bike has a Truvative Elita crankset with the GXP (hollow) bottom bracket, and I can't seem to find a Truvativ triple road replacement. SRAM ones are way too expensive.
Is there any way to add a granny ring to the existing crankset with some kind of adaptor / convertor? I realise I can't change the smaller 39T chainring for a smaller one - the bolt centres are 130BCD, and I really want a 30T chainring.
If I have to switch to a Shimano crankset, I'd also have to change the bottom bracket, and I can't really afford to buy both components.
For info, the front shifter is Ultegra, and rear cassette is a Shimano 11-25 10 speed. I don't want to switch to a 12-28 as it won't make enough of a difference with the 39T chainring.
Thanks in advance for any help!
Jim
I've just discovered this excellent forum, and am glad there's a 'proper' place to go with UK specific advice.
Getting to the point, I'm about to ride the C2C, and am worried that my road bike's gearing is too high. It's a Giant OCR1 and I've had it for about 5-6 years. Covered loads of miles, but mainly commuting.
I now realise the C2C's mountains are going to mean the gearing is too high to pedal with sensible cadence. What are my options on a limited budget?
Here's what I know: the Shimano 105 Flight Deck shifter has three positions, so I should be able to upgrade to a triple. However, the bike has a Truvative Elita crankset with the GXP (hollow) bottom bracket, and I can't seem to find a Truvativ triple road replacement. SRAM ones are way too expensive.
Is there any way to add a granny ring to the existing crankset with some kind of adaptor / convertor? I realise I can't change the smaller 39T chainring for a smaller one - the bolt centres are 130BCD, and I really want a 30T chainring.
If I have to switch to a Shimano crankset, I'd also have to change the bottom bracket, and I can't really afford to buy both components.
For info, the front shifter is Ultegra, and rear cassette is a Shimano 11-25 10 speed. I don't want to switch to a 12-28 as it won't make enough of a difference with the 39T chainring.
Thanks in advance for any help!

Jim
0
Comments
-
There is no adaptor AFAIK. But have you looked at fitting a compact chainset to give you the low gears you want? It sounds like you are a fairly strong rider if you're whisking around all over the place on a double, so you probably don't need the ultra-low-gear of a triple.- - - - - - - - - -
On Strava.{/url}0 -
On a limited budget you'll struggle.
A 12-28 cassette would be the first suggestion, but you've already covered that. Next would be a compact double as a direct replacement for your existing standard double chainset. I know nothing about Truvativ bottom brackets, so I don't know what you'd need. As you've found, they don't do triples.
You could phone Spa Cycles; they cater for the touring cyclist, and may be able to suggest a triple to fit your existing BB.
I think either way, a move to a triple chainset would mean a triple front mech too.
have a look on Ebay or the classified section here; there's generally plenty of triple chainsets up for grabs as people get fitter and / or upgrade0 -
- - - - - - - - - -
On Strava.{/url}0 -
Thanks for the fast replies. I am pretty fit, but I haven't ridden the OCR1 properly for a couple of years, so am a bit out of shape. Looking at the grades of some of the climbs, I know I can't stick with the standard double.
I'll look at a compact double to fit straight on to the GXP bottom bracket. Hopefully there's something close to 30T. If I can get a direct replacement, a switch to a 12-28 cassette as well could be the answer.
One thing - are front mechs classed as double or triple? I presumed you simply adjust the stops for a double, and open up the range for a triple! As I say, the front shifter definitely allows me to use a triple.
Cheers
Jim
EDIT - having just seen the link to the adaptor ring, that looks like a pretty affordable answer. So I just need that, plus my choice of granny ring? Presumably the adaptor's teeth will work with my hybrid Truvativ / Shimano setup?0 -
Triple front mechs do look very different from doubles, presumably so they can cope with the very different sized chainrings. (Google for some images) Also not sure if a standard double has the range of movement required to cover 3 chainrings; might not move far enough out to reach the big ring of a triple.
However, your existing mech may work well enough as a temporary fix.0 -
You might get problems with your mech if the chain won't clear the bottom of it. No harm in trying it before you buy a new one though.- - - - - - - - - -
On Strava.{/url}0 -
Yeah I think if you have a 30T granny ring (either with that adaptor or with a normal triple) the chain will catch on the bottom of the front derailleur cage. Not sure about range of movement.
Also rear derailleur wise, presumably you have a fairly short cage one atm, which may not be able to take up all of the chain slack when you're in some small-small combos. Can prob get away without changing the derailleur, but once you have got your new 30T ring on, it's definitely worth going through the small-small gear combos to see if you get any slack and noting which gears to avoid.0 -
Great. Thanks for all the advice. I hadn't thought of problems with the rear mech, but I wouldn't be using the small-small combinations anyway.
I think I'll go and check the front mech's range of movement now. However, it does lead to one further question: do I need some sort of spacer to move the two existing chainrings outwards to accommodate a third cog? Obviously the front mech extends out enough to get the chain on the large ring now, so all I need to check is whether it will go in further if i added a granny ring.
Even if I swapped the front mech for a triple-compatible model, would it work with the outer two rings in their current position?
Thanks again 8)0 -
I may be wrong but i am sure the max range of a the double front mech is only 16 teeth and it will not cope with the amount required for a triple.
Merlin Cycles doing a 105 Front mech for £18.99 at the mo and £17.09 if you join the VIP club which is free. and P&P is free with that.
http://www.merlincycles.co.uk/Bike+Shop ... e_1856.htm
Hope this helps0 -
I use a campag compact they are are available comparatively cheaply and being square taper the bbs are cheap too. They work well with the shimano shifters.0
-
Ok, quick update on this, mainly for anyone searching to do the same as I am.
Thanks all for the help, but I took the bike to my local bike shop for a bit of expert advice and the guy told me the new Shimano HG81 cassette goes from 11-36T, so that will sort out my problem with a minimum of hassle! (Costs only £35 from Chain Reaction Cycles).
There is one last question, though. I probably should replace my 10-speed HG chain as it's probably original (i.e. 5 years old). It doesn't slip at all, so I don;t think it has stretched or worn too badly.
The question is which chain to buy? Can I get away with a 9-speed Shimano chain? They're around half the price of the 10-speed ones!0 -
no0
-
10 speed only and old chains usually only slip with new cassettes as they wear the sprockets down to fit the stretched chain. Kmc chains are the best you don't have to go for the top models0
-
Chains don't stretch; they wear.
So to save paying £100+ for triple shifter (brake/gear lever) am I correct you are going for a MTB cassette, a long rear changer to suit like a Shimano XT, and a new chain.
The new cassette will need to be same number sprockets as now.The Wife complained for months about the empty pot of bike oil on the hall stand; so I replaced it with a full one.0 -
TrekVet, I stand corrected!
It's possible the HG81 cassette is a MTB one, but it shouldn't matter as it's 10-speed. I need a new chain as the current one won't be long enough, but I wasn't going to change the rear mech. That should work ok with the new cassette, and the guy in the shop didn't say I'd need to put a new one one, so with stick with the standard shimano 105 changer.0 -
The TA adaptor chainwheel will not work with any external bearing crankset as the inner ring will not clear the chainstay and cannot be spaced out significantly further as the axle cannot be interchanged.
You will DEFINITELY need a new rear mech with a 36T cog, and the shop guy should have told you this. Road mechs will often work with up to 30T and sometimes with 32T, but not bigger. Note that you will need to use a non-10-speed Shimano MTB derailleur for it to work with your road shifters as Shimano have increased the cable pull with DynaSys. You will undoubtedly need a new chain with the new cassette, not so much because of the length, but because the old chain will be worn and would almost certainly skip with a new cassette. If the chain was in good nick adding a few links would be unlikely to cause any problem.
IME it doesn't sound to me like the shop you're going to has much of a clue...0 -
Satanas, it sounds like you know what you're talking about, so what would you recommend? Either change chain, cassette and rear mech or change BB, crankset and front mech? Guessing rear will be cheaper, not least because i have tools for changing a cassette but not for the GXP bottom bracket.
If I go for the HG81 and new chain, which mech should I buy? (ideally an inexpensive model). What's different about the mech that means my 105 won't work?
Thanks for your help!0 -
Firstly, you say that your 105 shift lever "has three positions" - do you mean that literally, or is it meant to be triple-compatible? (Some shifters have a trim position, but are NOT triple-compatible.) Best to find the model number (peel back the brake hoods and look on the body underneath) and then go here: http://bit.ly/l1jQqm and see what you find. If the shifter is not triple-compatible then that rules out economically changing to a triple crankset.
1. If your shifters aren't going to play then getting a new chain, cassette and rear mech will be your best option. You will need a suitable 10 speed cassette (SLX is the cheapest option), a chain to match (best to use a Shimano 10 speed MTB chain) and a suitable 9 speed rear mech. Note that a 10 speed DynaSys (MTB) mech will not index with your shifters, and nor will a non-Shimano mech. This would be the simpler option and should be easy to get to work.
It is extremely unlikely(!) that your current rear mech will work with a cassette with more than 30T - maximum. It's possible it *might* barely scrape by with 32T, but the only way to find this out is to try it; a longer B-tension screw and/or a smaller upper jockey wheel may be required. (If this is all gibberish to you it will be much easier to buy a new mech!) If you intend to use a 34T cog, then any 9 speed Shimano MTB mech should be fine. With 36T you may need to use a Shadow-style mech; again, the only way to find out is to try it. The reason your mech probably won't work with a much-bigger cog is that the parallelogram angle on road mechs is less than on MTB mechs and so the upper jockey wheel won't move down as far, and so won't clear the largest cog(s) when it moves inwards.
2. If you decided to change the crankset you would most likely only need Allen keys to remove it; probably 5 & 8mm. The BB cups may or may not be compatible with non-Truvativ/Sram cranks - with some GXP BB cranks the axle diameter is different on the LHS and RHS. If it's 24mm on both sides you should be able to fit most Shimano external bearing cranksets, and many others. If you need to remove the BB cups you will need a special tool, but only for a few minutes so your LBS shouldn't charge much to do this. Fitting a new BB or cups should be a simple job with the right tools too.
You could probably get away with using your current rear mech with a triple provided that the cassette isn't too big (<28T is probably safe) and that you don't expect all the gears to work with the small ring - there won't be enough capacity to maintain chain tension with some gears. The current front mech might work (or not) but most likely not very well.
Good luck!0 -
double post - removed...0
-
Thanks Satanas,
Your advice has been spot on. I am still waiting for my Shimano M662 mech to arrive (been on back order) but I've fitted the 11-34T cassette and I also have a new HG74 chain ready to stick on when the mech arrives.
I tried the cassette with the 105 rear mech, and you were totally right - it didn't quite clear the 34T cog, so wouldn't have worked at all.
Given that the new kit will improve my ratio from 1.6 to about 1.1:1 I should be able to get over the Pennines ok. Weather forecast isn't brilliant for this weekend though, so looks like the gears will be the least of my worries!
Anyway, thanks again.0 -
Excellent! It's nice to hear things sometimes work out as expected. 8)0
-
Well, the M662 arrived the day before I left for Cumbria, and it worked perfectly. The M663 (Dyna-sys one) definitely did not work - I tried one, and the 105 shifters don't have anywhere enough cable pull for a Dyna-sys 10-speed!
However, having covered 145 miles with it all, it performed just about flawlessly, and the ratios were fine except for hills over about 10%.. where you really need a granny ring, or Superman fitness levels.
Now all I need to do is strip the bike down and give it a good clean0