[Dieselfan]

Hi all, Nice forum

I used to do loads of onroad races and loved it, until too many serious hit and run type accidents put me off bikes for the last 12 years.

Recently as in last week I bought a baby chair for my 3yr son and took my dad's unused mtb to a game reserve. I used to cycle here when I was young and loved the freedom and gravel roads, but now shees I hated it. I had an oldschool no shock, 18 spd with padded brakes and big seat. I never used to sink as much in the sand and 2.2bar was good. I could also raise or lower the handle bar with a simple allen key.

With my dad's bike he has shocks upfront, left side has a air valve, right side a turn type adjuster. Bottom has a rebound lever. The handle bar can't be raised and when I tried the bottom part of the fork came lose. When pedalling I found the front shock action annoying as it felt as if it sapped my power so I rode on "closed". The tyres recommend min 2.5bar but at that pressure the bike sank fast in sand esp with my kid on the back. It has discs and the brakes feel ok, just I remember right side being front and left being back, this is swopped.

Right I don't hate the bike but obviously I don't know how to set it up for me and how to set the shocks so that I can actually pedal ;(. My older bike had fat tyres which allowed great flotation. I have no idea if this bike is high end or not.

Sorry for the mouthful I just want to get back into things and feel my ignorance is ruining what is probably a good bike.

I'm not interested in what I see on yt, "downhills" but in XC.

 

[kneedrachen]

softer surface=less tire pressure.

your suspension may need a more viscous fluid and/or a stiffer spring.

A good bike shop will be a great benefit for you on this one.

 

[Poolie]

Your front fork most likely needs the air pressure checked and increased for your body weight. The air pump for that has a special fitting on it so would be better to have a local shop do it for you.

 

[Dieselfan]

The valve on the bike is a std schrader valve. I pumped it up to 7bar and although my body didn't push it down much it was noticeable when pedaling, your down stroke pushes the bike down. Have any of you guys cycled for yonks with the non shock bikes? It's almost like a non shock bike is a manual transmission and the shock bike an auto, there's a non directness about how the power is being applied.

I just checked this is the spec Raleigh RM 8.0

http://bikebay.co.za/popup_image.ph...9.JPG&osCsid=d38b2785aa3214bc2f6c2548597c4a91
http://www.mtbonline.co.za/averageguy/raleighcarbonmtb.htm

and the tyres are
http://www.maxxis.com/Bicycle/Mountain/CrossMark.aspx

Are these any good, there's not much space on the back frame for a wider tyre?

I want to perhaps buy this from my dad but not sure if it's a good bike for what I need?

Thanks again!

 

[Dieselfan]

More specifically, the tyres are 26x2.10 and pressures are 35-65 psi. kneedrachen when you say lower pressures can I go lower than 35? 35 seems too high for the sandy stuff? Should I go for a 26x2.3+?

 

[Poolie]

Over the weekend I put a new set of Maxxis Ignitors (29x2.1) on my bike and the pressure is sitting at 30psi. I weight 155lbs and can go down to about 20psi if need be before I have to worry too much about pinching tubes.

Some people like to go with as low a pressure as possible. Personally I prefer as high a pressure as I can get away with and still get traction. I think you spend a lot less time on the side of the trail changing tubes that way. Time to consider tubeless at that point too.

I'd start at 35psi and then try 30, then maybe 25. See what works for your riding conditions -- depending on your body weight you might need to adjust those numbers up or down.

 

[kneedrachen]

I'm not going to pretend to be the expert on tire pressure and surface. Someone might chime in here or maybe in the MTB section will be of more help (although I hear that Poolie guy is on the level). I do not have much MTB experience, but I do have overland motorcycle and rock-crawl experience, albeit limited.

For lowering your pressure, a lower pressure=larger footprint for the tire. A larger footprint will reduce the amount of pressure for a given area on the tire/ground interface. In essence, you'll float rather than sink, if you understand. Look at off-road/overland vehicles, most have an on-board air system to compensate for varying terrain/tire pressure requirements.

Now there's a caveat here. Lower pressure with tube wheel systems greatly increase the chances of a pinch flat (snakebite) as well as will require more effort for a given amount of work performed. Going tubeless is certainly one option as are wider tires. Remember though, heavier riders will need a higher tire pressure than a lighter rider to avoid pinch flats.

Ever notice you rarely see an original VW beetle stuck in the snow? Skinny, high pressure tires essentially "sunk" through the snow to the street below.

 

[Poolie]

Kneedrachen, you must have stayed at a Holiday Inn Express last night. Good post

 

[kneedrachen]

Every once in a while, I have a stroke of pure, intelligible genius. Rare, but it happens.

Actually my daughter slept through the night last night, and I overslept by about 20 minutes so I feel a bit more rested than usual.