Increase the Size of My Existing Chainset
My current bike 'Ridgeback Tempest 2006' - Chainset: Shimano TX71 with 48 38 and 28 tooth chainrings with Shimano C051 front derailleur.
Basically my wife is doing a triathlon, and she needs to use my bike but its so slow...
Is it striaght fwd to replace the chainset with a larger sized one more suited to road races, if so any recommendations.
Want to avoid the whole computer upgrade thing, where replacing one part has a knock on effect requiring you to replace everything but the cover. :oops:
Basically my wife is doing a triathlon, and she needs to use my bike but its so slow...
Is it striaght fwd to replace the chainset with a larger sized one more suited to road races, if so any recommendations.
Want to avoid the whole computer upgrade thing, where replacing one part has a knock on effect requiring you to replace everything but the cover. :oops:
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Comments
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Iain28 wrote:My current bike 'Ridgeback Tempest 2006' - Chainset: Shimano TX71 with 48 38 and 28 tooth chainrings with Shimano C051 front derailleur.
Basically my wife is doing a triathlon, and she needs to use my bike but its so slow...
Is it striaght fwd to replace the chainset with a larger sized one more suited to road races, if so any recommendations.
Want to avoid the whole computer upgrade thing, where replacing one part has a knock on effect requiring you to replace everything but the cover. :oops:
Is 48-11 not big enough? That's 40mph (ish) for me
Sounds like a hybrid to me - that's why it's slow, not the gearing.0 -
I can't even get 40mph (64kmph) downhill!!!
Pedalling downhill is useless - the pedals just turn limply as gravity takes over.
As for the flat lucky to average 30kmph and thats putting it in big style.0 -
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There has to be more to it than just posture.
I was thinking of upgrading to a Marin Highway 1 (similair riding position) and its labelled with giving roadies a run for they're money. Awaiting 2009 stock.
http://www.marin.co.uk/2008/bikedetail.php?ModNo=3863
but would prefer to avoid the £1.7k hit0 -
Iain28 wrote:There has to be more to it than just posture.
Yes there is - fitness, clipless pedals, a bike that fits, etc.but You seem to be asking if you can make that hybrid go faster by fitting higher gear ratios.
With the 48T chainring and (let's say) a 12t sprocket @ 80rpm (pretty low really) with 26" is 24.8mph. With a 11t sprocket you'll going 27mph. 80rpm is pretty low so there's plenty of scope of going faster.
Plenty of roadies use 48-11 as their biggest gear, there's a thread on here somewhere and I think the consensus was that 48-11 is big enough for everything bar higher Category road races.
With a hybrid you'll have massive aerodynamic resistance stopping you from spinning out anyway.... I reckon if you fitted larger chainrings you'd be on the middle ring more or grinding away in a stupidly low cadence on the big ring.0 -
My wife keeps talking about size too. Telling me I need to put more teeth in it, get it
bigger around, make it stronger, that sort off thing. But when I bought a new chain ring
she asked me what was wrong with the old one. I really don't understand women.
Dennis Noward
(It's not very big around but it sure is short)0 -
For the relatively brief time you are on a long downhill where you might run out of gears, the change is not worth it. Unless you run out of gears on the flat, which you would have to be impressively fit to do, then there is no need. I ride down a long hill here in Bath, and I do spin-out but still achieve 50mph with gravity and the initial pedalling effort. That said, I am beginning to think I am a bit reckless riding at this speed. Money would be better spent on wheels and decent narrow slick tyres, or getting a road bike.0
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One thing to watch out for when mounting large chainrings on MTBs & Hybrids is chainstay clearance... a possible knockon effect there is a new bottom bracket with a longer spindle... which will put the chainline too far out... meaning you may need a new frame.
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Thanks for the heads-up guys. Sounds like a nightmare waiting to happen. It would be heart breaking to buy a new chainset and bottom bracket just to find the frame won't work. Think I'm just going to have to buy a bigger shed for a new bike
I still disagree with that its due to fitness, shy of being Lance Armstrong's and Alberto Contador's love child whilst being doped up to the eyeballs with EPO, can't account for a doubling of speed and not freespinning after 50km/h downhill.
50mph downhill is crazy fast - fair play to you though. When I get to 60km/h (I work in km/h - bloody Garmin) my bike becomes the car out of Back to the Future - just waiting for the sparks to start flying. 80km/h would be nuts - one small size pothole from oblivion.
Good luck and stay safe guys0 -
some riders are either not fit enough or have a different muscular structure to which high cadence doesn't suit at all.There is nothing wrong with a lower cadence .
I am one who can appreciate a slower cadence style . I have always ridden with a lower cadence and used to manage 30mph on the flat with ease.
Lain its not difficult to change your 48t to a 50t or even 52t if you wish. There are a couple of things you need to be aware of. You will need to add some links to your existing chain . It would probably be better to buy a new chain .Unless your cassette and chainrings are very worn you do not need to change them.
There will be a bigger jump when changing up or down between chainrings so it may be better to go for the 50tooth ring
You need to measure the distance between your chainring fixing bolts centre to centre from which you can work out the BCD using a formulae on Sheldons site.
Lots of cheap chain rings on St Johns Cycles (SJS) website
http://www.sjscycles.co.uk/find.asp
If you change your chainrng from 48t to 52t it will be the same as changing from 13t to 12 t on your existing 48t chainring ie approx 8"
Better is..
You will get exactly the same effect by sticking with your existing chainset 48-38-28 and simply changing your cassette to a 11t up ie the difference between 11t and 12t is approx 8"
hope that makes sense0 -
peanut wrote:I am one who can appreciate a slower cadence style . I have always ridden with a lower cadence and used to manage 30mph on the flat with ease.
I'm masher, I used to rarely go above 60rpm, but I eventually discovered it's easier to go faster by pedalling faster than fitting a 55T ring .
I agree that you don't have it pedal with a high cadence, but it's cheaper and better on the knees in the long run.0 -
redddraggon wrote:peanut wrote:I am one who can appreciate a slower cadence style . I have always ridden with a lower cadence and used to manage 30mph on the flat with ease.
I'm masher, I used to rarely go above 60rpm, but I eventually discovered it's easier to go faster by pedalling faster than fitting a 55T ring .
I agree that you don't have it pedal with a high cadence, but it's cheaper and better on the knees in the long run.
I think you are right for the majority of riders but for a very few riders like me high cadence actually uses more energy .Perhaps if I weighed about 6 stone less and had more slow twitch than fast, I'd be able to use a higher cadence and save energy. :roll:
I've just fitted my first compact (50t-36t) and will try it out this weekend. Who knows maybe I'll manage a higher cadence and find it manageable. 0 -
before you shell out a load of cash, just try some cheap solutions
- fit skinny tyres - Conti do a 1" slick for 26" rims and they're v. fast
- consider dropping the front of the bike by flipping the stem, to reduce the aero drag
- also consider fitting narrower, straight bars and bar ends, for the same reason (see ebay they go for very little cash)
You should be able to bodge a much lower, more aero position just for the triathlon without spending much at all.
If you don't fancy a bodge then you need a road/tri bike really.
[and it's nothing to do with your gearing ] Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer0 -
maddog 2 wrote:before you shell out a load of cash, just try some cheap solutions
- fit skinny tyres - Conti do a 1" slick for 26" rims and they're v. fast
- consider dropping the front of the bike by flipping the stem, to reduce the aero drag
- also consider fitting narrower, straight bars and bar ends, for the same reason (see ebay they go for very little cash)
You should be able to bodge a much lower, more aero position just for the triathlon without spending much at all.
If you don't fancy a bodge then you need a road/tri bike really.
[and it's nothing to do with your gearing ]
excellent suggestions maddog. to which I would add pump your tyres up nice and hard ie 100lbs psi min if you haven't got a proper track pump you'll need one to do this comfortably. The difference will simply blow you away0 -
Iain28 wrote:I work in km/h - bloody Garmin
Have you tried Main Menu> Settings> System> Units?
(I know it then converts everything to Imperial measurements, but you can't have everything...)
RBIT0 -
Thanks for the advice, will have a play around and see whats best.
Guess we just asumed that it must be the gears (but as you have rightly pointed out there are so many other factors).
Its just frustrating when the one of the lycra brigade overtake you and you match them revolution for revolution, but yet they pull away effortlessly. I would buy a road bike if i didnt think I would become one of them.... only joking.
Might try a few bikes out at my local store and check out the diff for myself.
As for the Garmin - I've got so use to the metric system. Plus its a good distraction converting into miles in your head when your feeling the pain (xxkm divide by 8 multiply by 5).
Thanks again0 -
peanut wrote:I have always ridden with a lower cadence and used to manage 30mph on the flat with ease.
http://www.sjscycles.co.uk/find.asp
30 MPH on the flat "with ease". I'm really astounded that you would even think that
there is anyone out there who would believe this kind out statement. With ease
my a**
. 30 MPH with ease??? That must have been during your pro career.
Who did you ride for?
Let's quit the bragging, shall we???
Dennis Noward0 -
dennisn wrote:peanut wrote:I have always ridden with a lower cadence and used to manage 30mph on the flat with ease.
http://www.sjscycles.co.uk/find.asp
30 MPH on the flat "with ease". I'm really astounded that you would even think that
there is anyone out there who would believe this kind out statement. With ease
my a**. 30 MPH with ease??? That must have been during your pro career.
Who did you ride for?
Let's quit the bragging, shall we???
Dennis Noward
have you always been an under-achiever Dennis ?
Anyway I could only keep that kind of speed up for about 36 hours ahem seconds 0 -
dennisn wrote:Let's quit the bragging, shall we???
You don't need to be a pro to hit 30mph on the flat :shock: Plenty of amateur TTers do 25milers in under the hour, some well under the hour - so there's no reason why they couldn't hit 30mph with ease.
I can sprint to well over 30mph (and then maintain it for a while), but I doubt any pro team will come looking for me.0
