Cassette's

by Gkam84   August 30, 2011  

Some advice needed, I've managed to get a mate to come road cycling with me, he's a mountain biker and is just getting the hand of the shifters, bars and riding position, so I'm letting him use my winter/spare bike, which is a Raleigh Sprint http://www.evanscycles.com/products/raleigh/sprint-2010-road-bike-ec023528

The problem he's having is keeping spinning up some of the hills i ride even on the 25 gear, so i want to make it easier on him so that he doesn't just give up on me and i'm back to riding solo

So my thought is to change the cassette, but without changing anything else, so here's where i'm stuck, how big can i go without changing derailleurs and shifters

Could i just switch out the 12-25 for this 11-30 http://www.ebay.co.uk/itm/Shimano-Altus-8-Speed-Bike-Cassette-11-30-CSHG...

or can i go even bigger? as i've see this 11-32 http://www.ebay.co.uk/itm/380362834060?ssPageName=STRK:MEWAX:IT&_trksid=...

Just want to give him as much range as possible without costing me a fortune, ideas please Big Grin

8 user comments

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Check the shimano website for the tech sheet on the rear mech. This should state the max number of teeth it can handle.

Good luck converting him from the dark side.

TheHatter's picture

posted by TheHatter [810 posts]
30th August 2011 - 17:37

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http://techdocs.shimano.com/media/techdocs/content/cycle/SI/2300/SI_5XA0...

So i think thats it, But its confusing, it says

Total Capacity 35 teeth or less
Largest Sprocket 26t
Smallest Sprocket 12t
Front Chain wheel Difference 22t

So does that mean i could only go 12-26 with that one?

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posted by Gkam84 [8639 posts]
30th August 2011 - 18:00

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from my limited knowledge you can generally get away with a maximum 28T sprocket with a medium cage shimano rear mech, anything larger and you need a long cage mech, fit a mtb mech, make sure the chain is long enough and you can get an 12-32 on there no problem..

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posted by Fringe [1081 posts]
30th August 2011 - 20:24

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Work out your teeth capacity by adding the difference of the chain rings to the difference of the lrg sprocket and small sprocket. That figure gives you the max teeth your rear mech can deal with. As fringe says you need to take into account the size of the rear mech. You will also need to stick with the same amount of sprockets currently on your machine for the shifters to cope. You can get a 13:29 which works well with a compact chainset (found this flicking through a repair manual) looking at the spec of your bike you may get away with that. I like fringe have limited knowledge of the arcne art of the chainset Big Grin

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posted by giff77 [1032 posts]
30th August 2011 - 22:27

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Right so the difference in my chainset is 16 and my cassette is 13, so in theory a 29 should work?

I dont mind having to get a new rear mech and chain cause they aint hugely expensive, i know i can only got for a 8 speed cassette as thats what i have now and thats what the shifters are for

So with the 34-50 on the front with a long mech and new chain, could i get away with something like a 11-34?

I just want to give him as much range as possible without changing the full groupset and without costing me a fortune because its my bike, once i've got him into climbing and used to it, then i'll get him to work down and back to normal ratio's like i'm using 39-52 and 13-26, then he might get his own bike as he's only used to cross country stuff on his MTB and its all fairly flat

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posted by Gkam84 [8639 posts]
30th August 2011 - 23:04

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In my experience in switching between the two is that it takes a while to get used to the difference in climbing. I had a compact chainset and a 27-12 cassette to start with, and within a few months ended up changing to a double chainset and 23-11 cassette. Generaly mountain bikers ride with a much higher cadence than road riders so they can ride efficiently over rough ground. Although none of the hills I ride up are more than about 2 miles long and although they are graded up to 14% steepness is only in shost bursts. So depending on what you ride my advice may be irrelevant

posted by mrkeith119 [85 posts]
31st August 2011 - 2:10

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I know he'll get used to in the long run Devil I just dont want him to lose the rag with it, so making it easier would help

I regularly cycle The Lecht, Spittal of Glenshee or The Cairn 0 Mount and if you dont, look them up somewhere, they ramp up something stupid, there are points on the Cairn where i struggle at 30% for nigh on half a mile, i tend to jump off and push, but there are also steady 20-25% for a mile or two on other parts of my rides, where at the moment he just jumps off and pushes up, but if he could just spin a high gear, he would get there in the end alla Cav style Devil

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posted by Gkam84 [8639 posts]
31st August 2011 - 6:10

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Wouldn't go the 11:34 if he's in the granny ring he'll probably have to make 2/3 revolutions to turn the rear wheel once Devil I would go up to 28/29 and have 12 smallest. That way he has several spare teeth for the climb. And something small for powering down the decent Big Grin Worst case scenario you could always push him up those climbs - they look real buggers. I use a 12:26 with a double standard and tackle Crow Road and Take me Doone in the Campsies and have learnt to value the granny ring Big Grin

If not already, give him a few hints on how to tackle the climb as well. Maybe that's why he's running out of sprockets and jumping off. Hope it works out gkam

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posted by giff77 [1032 posts]
31st August 2011 - 14:48

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