Inflating presta valve tyres at a garage?

toontra

I do this with my schrader valve MTB tyres regularly, but I'm wondering if it's OK to do this with presta-valved road tubes (23) using an presta/schrader adaptor. I'm doing a several-day trip and want to keep my tyres up to 110 and I don't think my mini pump will manage this (also it doesn't have a pressure gauge).

Also, are the gauges on garage pumps generally reliable?

LangerDan

Garage air supplies won't normally get anywhere near this. I'd guess that most top-out at ~ 60 psi or less. In my experience, garage air gauges can be out by between 2 - 5 psi @ 30 psi, the situation will probably be worse at higher pressures. ( I think there is a legal requirement for the accuracy of garage airlines in reality after the inflator has been bounced off the ground a few dozen times, all bets are off)

IMHO, get a better pump

itisaboutthebike

Most garages won;t let you inflate bike tyres anyway - I think for H&S reasons (the big chains anyway).

With a decent hand pump you should get be able to get to 100psi easily.

aracer

If you're that bothered get a different pump - the Topeak Road Morph is recommended - it will do 110psi easily and has a gauge. Though I'm not quite sure what sort of multi-day trip you'd do where you didn't have support and wanted to run tyres that high pressure anyway.

toontra

aracer wrote:

Though I'm not quite sure what sort of multi-day trip you'd do where you didn't have support and wanted to run tyres that high pressure anyway.

A solo 6-day LEJoG, which means 150 miles + per day. I'm running Pro 3 Race Michelins on Open Pro rims so I always try and keep the pressures up to avoid pinch flats.

The Road Morph looks good but is expensive (£30) and comparatively heavy at almost 300g - I need to travel light.

I guess I could pop in to a LBS every couple of days (or after any p*******s) and borrow their track pump.

aracer

toontra wrote:

A solo 6-day LEJoG, which means 150 miles + per day. I'm running Pro 3 Race Michelins on Open Pro rims so I always try and keep the pressures up to avoid pinch flats.

Carrying kit? I'm really not convinced tyrea that narrow are ideal if you are. Riding what sort of bike?

toontra

aracer wrote:

Carrying kit? I'm really not convinced tyrea that narrow are ideal if you are. Riding what sort of bike?

The bike's a Van Nicholas Yukon. It has rack-mounts so I'll have a rackpack with around 2.5k of gear, so pretty light. I'm 70k, so combined the weight should be fine for the P3R's. I've done lots of 150 mile day rides with this setup without any problems.

My worry isn't about getting the tyres pumped up after a p******e (I'm sure I can get to 100psi without problem with my current mini pump), but more to do with maintaining pressure and knowing what the pressure is. I somehow doubt that the gauges in mini-pumps are as accurate as on a decent track pump.

ColinJ

I'm currently 95 kg ( :oops: ) and I run 23s at about 100 psi rear and 90 psi front and I never get pinch flats. Okay, about 10 years ago I hit a housebrick in the road and did then, but that's about it. I find the lower pressures more comfortable.

As for maintaining pressure... I don't need to top my tyre pressures up more than once every couple of weeks so surely you'd be okay for 6 days?

I do use the gauge on my track pump at home, but I'd be quite happy to guess the pressures out on the road. Too high is difficult to achieve. Too low is fairly obvious - just press the tyres in with your thumb. Assuming that you don't have incredibly strong hands - you shouldn't be able to make much of an impression. Does a few psi here or there really matter?