Novice has questions?

[ChrisCarson]

Having left cycling many years ago, the need for fitness and personal cheap transport has rekindled a renewed interest.

I bought this.... http://www.ideal-cycles.co.uk/index_71.htm

It seems to suit the purpose, which is intended to be lightweight, sturdy and agile and to have a decent turn of top speed. And not too expensive.

Although I’ve found the overall gearing is too low.

Now this is where I need some advice.

What can I do to improve the gearing. Presumably I would need to change the front crankset to something a little higher ratio. The rear cassette seems Ok.

What kind of a job is it to change the front chain-set. Is it quick and simple, or long, convoluted and expensive?

The front crankset is : SHIMANO TX71 48X38X28TX170MM W/CG

As it’s strictly for roads and will never see a mountain, I was thinking more in terms of : 54x48x38.........is that feasible. Or have I made too much hard work for myself? What’s the general optimum?

Then what should I buy?.........should I stick to Shimano or is there something better perhaps? How easy is it to source parts? I contacted the UK Shimano distributor from their web site and they haven’t bothered to answer me. Presumably they feel it’s better to ignore idiot questions from people like me. http://www.ultimatepursuits.co.uk Looking in the parts catalogue is overwhelming, especially as I don’t know what it is that I need? There is a replacement TX71 but it’s the same as I have now. Are replaceable chain-rings available for this model?

Finally, why do the gears slip & jump? When I start to go uphill, I shift to a lower gear and the gears seem to slip. It’s as if the chain is slipping on the cogs and can’t get traction. For a few seconds it feels ok, then the chain slips again. Why is that? Is this a common phenomenon or is it operator error?

 

[butchh]

For the taller gears it may be easier to replace/change the rear gear cluster. You have a 14/28 and this is low for road work. Better a 12/25 or something similar. Going from 14 to 12 tooth will give you roughly 14% more ground speed. You may even be able to find an 11 tooth like I have on my Specialized Crossroads. It is actually geared higher than my road bike.

The skipping you describe is likely due to lack of lubrication of the rear der. You will notice that when you go to a larger sprocket on the rear the der moves forward against spring pressure. This is normal, but if the der is binding, there is inadequate tension on the chain and it literally jumps over the gear. Not a good thing.

Also, for road work, a 40mm tire is quite large. You might look into something not so large, say around 28mm. There are some limitations due to the width of your rim.

 

[Retro Grouch]

Faster gears are going to be harder to do than you think.

You have a spin-on freewheel in the back. The last time that I looked, Shimano still offered a 6-speed 13/34 freewheel. That'll give you about 5 more gear inches (95) on the top end. That's not a whole lot, but it's enough to notice. It's probably the best that youre going to do without having to buy a lot of parts. Besides the freewheel, you'll also need a new longer chain to go with the wider range freewheel. A $5.00 freewheel remover and a chain breaker are the only special tools you would need to do the conversion.

Changing to a road crankset with a 52 big ring would give you around 100 gear inches but changing the front isn't going to be done very easily. Besides a new crankset, bottom bracket and chain, your front derailleur won't be able to handle the 52 big ring very well. Changing the front derailleur would be a project because you have a top pull front derailleur and all of the road style front derailleurs are bottom pull.

The skipping that you are feeling now is almost surely due to a misadjusted rear derailleur. Look up "Rear derailleurs" on the Park Tool website for step-by-step adjustment directions.

 

[gclark8]

I have solved this problem on many bikes. The 14-28 spin-on is Junior Gearing.

Shimano sell a "normal" 7 speed spin-on 11-28 which will work with all the existing *components. The one in my hand now is: "MF-HG50 11-28", about $40 in Aus.

Leave the crankset. The TX71 with an 11 tooth top gear sprocket will give a higher top speed than a 52-12 road combination. http://www.sheldonbrown.com/gears/

You will find *HG Chain will work better with the HG cranks and HG sprockets than the IG chain.

Riding style, see if you can pedal at a higher cadence, 85-90 rpm, it puts less strain on components, particularly on hills.

Those tyres, they will hold you back, Conti Ultra Gator Skins in 23mm will make the bike go to its maximum potential, however 28mm is the maximum width I would recommend.

 

[ChrisCarson]

Ok........

I would like to thank everybody, especially George for all your help.

I now have a much better understanding of how all this works.

I’ve bought....... Shimano Sora HG30 7-speed cassette 11 - 28T

· Durable 7-speed ATB cassette

· Hyperglide sprockets have a computer designed tooth configuration with contoured shift gates, resulting in a crisp smooth shift even under load

· Close ratio gearing allows a more efficient use of energy through finer cadence control

· Sprockets are cut away to reduce weight without reducing rigidity

· Nickel-plated finish offers hard wearing resistance to corrosion

· Corrosion-resistant steel cassette lockring

· For 7-speed HG chains



Shimano Deore HG70 chain 7 / 8-speed - 114 links

· Hyperglide (HG) series 7- or 8-speed compatible chain, recommended for 1995 and earlier Deore LX / STX-RC and 1999 and earlier 105 drivetrains

· HG technology has chamfered inner plates to optimise shifting performance on HG sprockets

· Durability is assured through a chromising treatment on link pins, and the heat treatment of rollers, pins, and plates

· Mushrooming of the pins gives unsurpassed side-plate retention, enabling the chain to far exceed the BS/ISO standard for breaking force

· 7.3 mm chain width, optimised for 7- and 8-speed HG drivetrains

· Corrosion-resistant grey finish on inner and outer plates

· 114 links, 335 g



As well as Park Tool Sprocket/Cassette Remover all of which were sourced either eBay or Froogle thus saving hard earned cash.


All I need next is a Chain Link removing and rejoining tool.........for the new chain.


Anyone got any suggestions?


Next to come in due course will be the Conti Ultra Gator Skins. 700x25 seems to be an optimum choice or perhaps x23 and really go for it...........


I’m going to do the work myself but will learn and prepare before I start....No doubt if I get stuck you’ll be hearing from me in due course.


On another note, I’m not surprised the der are going to need some adjustment. Considering the shop let me go with a new bike with flat tyres, I doubt very much if the adjustment occurred to them before they delivered the bike to me.


If anyone has any further tips learnt by many years of experience, on the gear adjusting techniques to save them from jumping and slipping on their cogs, all info will be gratefully received. Meanwhile I shall check out the Park site as per excellent suggestion........



Chris..........