A basic gearing question

JAMESWRIGHT2004 said:

Hi guys, First time here, so I hope not to offend you with my basic knowledge but I'm in need of some help. I have been riding my road bike for a little under 2 years now, its a Trek 1.5 (Triple). I cover a few miles but in the winter as most people do, ease off on the cycling. I have a parabolic roller I use when the weather is just too bad which is well and good, but it absolutly knackers my tyres for the amount of mileage covered. So the idea was to buy a cheap wheelset/tyres and casette that i can just throw on and use on the roller rather than use my nicer (On-road) equipment. But having never have to replace the rear cassette I have never had to look at alternatives. I have found on the internet a nice cheap package deal but it comes with a Shimano MF-TZ21 7 Speed freewheel casstte. My question to you is, would there be any problem in compatability with this set-up on my current bike. As I have said I have a Trek 1.5t Details:

Shimano Tiagra STI (9 speed)

Shimano Tiagra

Shimano Tiagra

FSA Vero, 50/39/30 (Triple)

SRAM PG-950 11-26 (9 speed)

I would imagine ideally with the shifters you would have a 9 speed gear? But I essentially use the rollers as a fixie and dont change the gears anyway so if I could find a nicely alligned gear would this be ok? I throw myself at your superior knowledge. Thanks in advance. James

A 7 spd cassette isn't spaced correctly for your 9 spd group. Frankly, I don't know of anyone using different cassettes on their trainers. Some people do use a junker bike or summat for indoor training. With all that said, I'd suggest you look at eBay for cheap cassettes. If you are set on only using one gear, you can buy pretty much any cassette that will match the spline pattern on your hub, and tear that cassette apart to select the gear you want to use. That gear can positioned on the hub, then, with the appropriate diameter spacers. Someone else will have to chime in with the exact specs. There are also a few companies that make spacers just for that purpose. Here are two kits that do just that: http://www.benscycle.net/index.php?main_page=product_info&products_id=8070&zenid=77aa618e070c97ad6522a62446a72cc5 http://surlybikes.com/parts/spacer_kit

Your cheap 7-speed setup will work just fine as long as you are using it as a fixed gear/single-speed setup.